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Third-Party Package
This third-party package's source repository does not contain a package manifest. Instead, its package manifest is stored in its release repository. In order to build this package from source in a Catkin workspace, please download its package manifest.Package Summary
| Tags | No category tags. |
| Version | 1.2.0 |
| License | BSD |
| Build type | CATKIN |
| Use | RECOMMENDED |
Repository Summary
| Checkout URI | https://github.com/ionelmc/python-tblib.git |
| VCS Type | git |
| VCS Version | master |
| Last Updated | 2024-05-02 |
| Dev Status | MAINTAINED |
| CI status | No Continuous Integration |
| Released | RELEASED |
| Tags | No category tags. |
| Contributing |
Help Wanted (0)
Good First Issues (0) Pull Requests to Review (0) |
Package Description
Traceback fiddling library. Allows you to pickle tracebacks.
Additional Links
Maintainers
- AlexV
Authors
- Ionel Cristian Mărieș
Overview
+———————————–+———————————–+
| docs | Documentation Status |
+———————————–+———————————–+
| tests | | ![GitHub Actions Build Status] |
| | (https://github.com/ionelmc/pytho |
| | n-tblib/actions/workflows/github- |
| | actions.yml/badge.svg) |
| | | Coverage Status |
+———————————–+———————————–+
| package | | ![PyPI Package latest release] |
| | (https://img.shields.io/pypi/v/tb |
| | lib.svg) |
| | PyPI Wheel |
| | Supported versions |
| | Supported implementations |
| | | 
|
+———————————–+———————————–+
Serialization library for Exceptions and Tracebacks.
- Free software: BSD license
It allows you to:
- Pickle tracebacks and raise exceptions with pickled tracebacks in different processes. This allows better error handling when running code over multiple processes (imagine multiprocessing, billiard, futures, celery etc).
- Create traceback objects from strings (the
from_stringmethod). No pickling is used. - Serialize tracebacks to/from plain dicts (the
from_dictandto_dictmethods). No pickling is used. - Raise the tracebacks created from the aforementioned sources.
- Pickle an Exception together with its traceback and exception chain
(
raise ... from ...) (Python 3 only)
Again, note that using the pickle support is completely optional. You are solely responsible for security problems should you decide to use the pickle support.
Installation
pip install tblib
Documentation
::: {.contents local=””} :::
Pickling tracebacks
Note: The traceback objects that come out are stripped of some attributes (like variables). But you'll be able to raise exceptions with those tracebacks or print them - that should cover 99% of the usecases.
>>> from tblib import pickling_support
>>> pickling_support.install()
>>> import pickle, sys
>>> def inner_0():
... raise Exception('fail')
...
>>> def inner_1():
... inner_0()
...
>>> def inner_2():
... inner_1()
...
>>> try:
... inner_2()
... except:
... s1 = pickle.dumps(sys.exc_info())
...
>>> len(s1) > 1
True
>>> try:
... inner_2()
... except:
... s2 = pickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s2) > 1
True
>>> try:
... import cPickle
... except ImportError:
... import pickle as cPickle
>>> try:
... inner_2()
... except:
... s3 = cPickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s3) > 1
True
Unpickling tracebacks
>>> pickle.loads(s1)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s2)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s3)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
Raising
>>> from six import reraise
>>> reraise(*pickle.loads(s1))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s2))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s3))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
Pickling Exceptions together with their traceback and chain (Python 3 only)
>>> try: # doctest: +SKIP
... try:
... 1 / 0
... except Exception as e:
... raise Exception("foo") from e
... except Exception as e:
... s = pickle.dumps(e)
>>> raise pickle.loads(s) # doctest: +SKIP
Traceback (most recent call last):
File "<doctest README.rst[16]>", line 3, in <module>
1 / 0
ZeroDivisionError: division by zero
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<doctest README.rst[17]>", line 1, in <module>
raise pickle.loads(s)
File "<doctest README.rst[16]>", line 5, in <module>
raise Exception("foo") from e
Exception: foo
BaseException subclasses defined after calling
pickling_support.install() will not retain their traceback and
exception chain pickling. To cover custom Exceptions, there are three
options:
-
Use
@pickling_support.installas a decorator for each custom Exception``` {.sourceCode .python}
from tblib import pickling_support
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP
pickling_support.install() # install for all modules imported so far
@pickling_support.install … class CustomError(Exception): … pass
```
Eventual subclasses of
CustomErrorwill need to be decorated again. -
Invoke
pickling_support.install()after all modules have been imported and all Exception subclasses have been declared``` {.sourceCode .python}
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP from tblib import pickling_support
Declare your own custom Exceptions
class CustomError(Exception): … pass
Finally, install tblib
pickling_support.install()
```
-
Selectively install tblib for Exception instances just before they are pickled
``` {.sourceCode .python} pickling_support.install(
, [Exception instance], ...) ```
The above will install tblib pickling for all listed exceptions as well as any other exceptions in their exception chains.
For example, one could write a wrapper to be used with ProcessPoolExecutor, Dask.distributed, or similar libraries:
>>> from tblib import pickling_support
>>> def wrapper(func, *args, **kwargs):
... try:
... return func(*args, **kwargs)
... except Exception as e:
... pickling_support.install(e)
... raise
What if we have a local stack, does it show correctly ?
Yes it does:
>>> exc_info = pickle.loads(s3)
>>> def local_0():
... reraise(*exc_info)
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> local_2()
Traceback (most recent call last):
File "...doctest.py", line ..., in __run
compileflags, 1) in test.globs
File "<doctest README.rst[24]>", line 1, in <module>
local_2()
File "<doctest README.rst[23]>", line 2, in local_2
local_1()
File "<doctest README.rst[22]>", line 2, in local_1
local_0()
File "<doctest README.rst[21]>", line 2, in local_0
reraise(*exc_info)
File "<doctest README.rst[11]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
It also supports more contrived scenarios
Like tracebacks with syntax errors:
>>> from tblib import Traceback
>>> from examples import bad_syntax
>>> try:
... bad_syntax()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[58]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[57]>", line 2, in <module>
bad_syntax()
File "...tests...examples.py", line 18, in bad_syntax
import badsyntax
File "...tests...badsyntax.py", line 5
is very bad
^
SyntaxError: invalid syntax
Or other import failures:
>>> from examples import bad_module
>>> try:
... bad_module()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[61]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[60]>", line 2, in <module>
bad_module()
File "...tests...examples.py", line 23, in bad_module
import badmodule
File "...tests...badmodule.py", line 3, in <module>
raise Exception("boom!")
Exception: boom!
Or a traceback that's caused by exceeding the recursion limit (here we're forcing the type and value to have consistency across platforms):
>>> def f(): f()
>>> try:
... f()
... except RuntimeError:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(RuntimeError, RuntimeError("maximum recursion depth exceeded"), tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
...
RuntimeError: maximum recursion depth exceeded
Reference
tblib.Traceback
It is used by the pickling_support. You can use it too if you want
more flexibility:
>>> from tblib import Traceback
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.to_dict
You can use the to_dict method and the from_dict classmethod to
convert a Traceback into and from a dictionary serializable by the
stdlib json.JSONDecoder:
>>> import json
>>> from pprint import pprint
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
... tb_dict = tb.to_dict()
... pprint(tb_dict)
{'tb_frame': {'f_code': {'co_filename': '<doctest README.rst[...]>',
'co_name': '<module>'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 5},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_2'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_1'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_0'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': None}}}}
tblib.Traceback.from_dict
Building on the previous example:
>>> tb_json = json.dumps(tb_dict)
>>> tb = Traceback.from_dict(json.loads(tb_json))
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.from_string
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
If you use the strict=False option then parsing is a bit more lax:
>>> tb = Traceback.from_string("""
... File "bogus.py", line 123, in bogus
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """, strict=False)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "bogus.py", line 123, in bogus
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
tblib.decorators.return_error
>>> from tblib.decorators import return_error
>>> inner_2r = return_error(inner_2)
>>> e = inner_2r()
>>> e
<tblib.decorators.Error object at ...>
>>> e.reraise()
Traceback (most recent call last):
...
File "<doctest README.rst[26]>", line 1, in <module>
e.reraise()
File "...tblib...decorators.py", line 19, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 25, in return_exceptions_wrapper
return func(*args, **kwargs)
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
How's this useful? Imagine you're using multiprocessing like this:
# Note that Python 3.4 and later will show the remote traceback (but as a string sadly) so we skip testing this.
>>> import traceback
>>> from multiprocessing import Pool
>>> from examples import func_a
>>> pool = Pool() # doctest: +SKIP
>>> try: # doctest: +SKIP
... for i in pool.map(func_a, range(5)):
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
for i in pool.map(func_a, range(5)):
File "...multiprocessing...pool.py", line ..., in map
...
File "...multiprocessing...pool.py", line ..., in get
...
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate() # doctest: +SKIP
Not very useful is it? Let's sort this out:
>>> from tblib.decorators import apply_with_return_error, Error
>>> from itertools import repeat
>>> pool = Pool()
>>> try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 4, in <module>
i.reraise()
File "...tblib...decorators.py", line ..., in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line ..., in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line ..., in apply_with_return_error
return args[0](*args[1:])
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate()
Much better !
What if we have a local call stack ?
>>> def local_0():
... pool = Pool()
... try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... finally:
... pool.close()
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> try:
... local_2()
... except:
... print(traceback.format_exc())
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
local_2()
File "<doctest README.rst[...]>", line 2, in local_2
local_1()
File "<doctest README.rst[...]>", line 2, in local_1
local_0()
File "<doctest README.rst[...]>", line 6, in local_0
i.reraise()
File "...tblib...decorators.py", line 20, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 27, in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line 47, in apply_with_return_error
return args[0](*args[1:])
File "...tests...examples.py", line 2, in func_a
func_b()
File "...tests...examples.py", line 6, in func_b
func_c()
File "...tests...examples.py", line 10, in func_c
func_d()
File "...tests...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
Other weird stuff
Clearing traceback works (Python 3.4 and up):
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> import traceback, sys
>>> if sys.version_info > (3, 4):
... traceback.clear_frames(tb)
Credits
- mitsuhiko/jinja2 for figuring a way to create traceback objects.
CHANGELOG
Changelog
3.0.0 (2023-10-22)
- Added support for
__context__,__suppress_context__and__notes__. Contributed by Tim Maxwell in #72. - Added the
get_localsargument totblib.pickling_support.install(),tblib.Tracebackandtblib.Frame. Fixes #41. - Dropped support for now-EOL Python 3.7 and added 3.12 in the test grid.
2.0.0 (2023-06-22)
- Removed support for legacy Pythons (2.7 and 3.6) and added Python 3.11 in the test grid.
- Some cleanups and refactors (mostly from ruff).
1.7.0 (2020-07-24)
- Add more attributes to
FrameandCodeobjects for pytest compatibility. Contributed by Ivanq in #58.
1.6.0 (2019-12-07)
- When pickling an Exception, also pickle its traceback and the
Exception chain (
raise ... from ...). Contributed by Guido Imperiale in #53.
1.5.0 (2019-10-23)
- Added support for Python 3.8. Contributed by Victor Stinner in #42.
- Removed support for end of life Python 3.4.
- Few CI improvements and fixes.
1.4.0 (2019-05-02)
- Removed support for end of life Python 3.3.
- Fixed tests for Python 3.7. Contributed by Elliott Sales de Andrade in #36.
- Fixed compatibility issue with Twised
(
twisted.python.failure.Failureexpected aco_codeattribute).
1.3.2 (2017-04-09)
- Add support for PyPy3.5-5.7.1-beta. Previously
AttributeError: 'Frame' object has no attribute 'clear'could be raised. See PyPy issue #2532.
1.3.1 (2017-03-27)
- Fixed handling for tracebacks due to exceeding the recursion limit. Fixes #15.
1.3.0 (2016-03-08)
- Added
Traceback.from_string.
1.2.0 (2015-12-18)
- Fixed handling for tracebacks from generators and other internal improvements and optimizations. Contributed by DRayX in #10 and #11.
1.1.0 (2015-07-27)
- Added support for Python 2.6. Contributed by Arcadiy Ivanov in #8.
1.0.0 (2015-03-30)
- Added
to_dictmethod andfrom_dictclassmethod on Tracebacks. Contributed by beckjake in #5.
Wiki Tutorials
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You can check on the ROS Wiki Tutorials page for the package.
Dependant Packages
No known dependants.
Launch files
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Messages
No message files found.
Services
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Plugins
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Recent questions tagged tblib at Robotics Stack Exchange
Third-Party Package
This third-party package's source repository does not contain a package manifest. Instead, its package manifest is stored in its release repository. In order to build this package from source in a Catkin workspace, please download its package manifest.Package Summary
| Tags | No category tags. |
| Version | 1.2.0 |
| License | BSD |
| Build type | CATKIN |
| Use | RECOMMENDED |
Repository Summary
| Checkout URI | https://github.com/ionelmc/python-tblib.git |
| VCS Type | git |
| VCS Version | master |
| Last Updated | 2024-05-02 |
| Dev Status | MAINTAINED |
| CI status | No Continuous Integration |
| Released | RELEASED |
| Tags | No category tags. |
| Contributing |
Help Wanted (0)
Good First Issues (0) Pull Requests to Review (0) |
Package Description
Traceback fiddling library. Allows you to pickle tracebacks.
Additional Links
Maintainers
- AlexV
Authors
- Ionel Cristian Mărieș
Overview
+———————————–+———————————–+
| docs | Documentation Status |
+———————————–+———————————–+
| tests | | ![GitHub Actions Build Status] |
| | (https://github.com/ionelmc/pytho |
| | n-tblib/actions/workflows/github- |
| | actions.yml/badge.svg) |
| | | Coverage Status |
+———————————–+———————————–+
| package | | ![PyPI Package latest release] |
| | (https://img.shields.io/pypi/v/tb |
| | lib.svg) |
| | PyPI Wheel |
| | Supported versions |
| | Supported implementations |
| | | |
+———————————–+———————————–+
Serialization library for Exceptions and Tracebacks.
- Free software: BSD license
It allows you to:
- Pickle tracebacks and raise exceptions with pickled tracebacks in different processes. This allows better error handling when running code over multiple processes (imagine multiprocessing, billiard, futures, celery etc).
- Create traceback objects from strings (the
from_stringmethod). No pickling is used. - Serialize tracebacks to/from plain dicts (the
from_dictandto_dictmethods). No pickling is used. - Raise the tracebacks created from the aforementioned sources.
- Pickle an Exception together with its traceback and exception chain
(
raise ... from ...) (Python 3 only)
Again, note that using the pickle support is completely optional. You are solely responsible for security problems should you decide to use the pickle support.
Installation
pip install tblib
Documentation
::: {.contents local=””} :::
Pickling tracebacks
Note: The traceback objects that come out are stripped of some attributes (like variables). But you'll be able to raise exceptions with those tracebacks or print them - that should cover 99% of the usecases.
>>> from tblib import pickling_support
>>> pickling_support.install()
>>> import pickle, sys
>>> def inner_0():
... raise Exception('fail')
...
>>> def inner_1():
... inner_0()
...
>>> def inner_2():
... inner_1()
...
>>> try:
... inner_2()
... except:
... s1 = pickle.dumps(sys.exc_info())
...
>>> len(s1) > 1
True
>>> try:
... inner_2()
... except:
... s2 = pickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s2) > 1
True
>>> try:
... import cPickle
... except ImportError:
... import pickle as cPickle
>>> try:
... inner_2()
... except:
... s3 = cPickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s3) > 1
True
Unpickling tracebacks
>>> pickle.loads(s1)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s2)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s3)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
Raising
>>> from six import reraise
>>> reraise(*pickle.loads(s1))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s2))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s3))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
Pickling Exceptions together with their traceback and chain (Python 3 only)
>>> try: # doctest: +SKIP
... try:
... 1 / 0
... except Exception as e:
... raise Exception("foo") from e
... except Exception as e:
... s = pickle.dumps(e)
>>> raise pickle.loads(s) # doctest: +SKIP
Traceback (most recent call last):
File "<doctest README.rst[16]>", line 3, in <module>
1 / 0
ZeroDivisionError: division by zero
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<doctest README.rst[17]>", line 1, in <module>
raise pickle.loads(s)
File "<doctest README.rst[16]>", line 5, in <module>
raise Exception("foo") from e
Exception: foo
BaseException subclasses defined after calling
pickling_support.install() will not retain their traceback and
exception chain pickling. To cover custom Exceptions, there are three
options:
-
Use
@pickling_support.installas a decorator for each custom Exception``` {.sourceCode .python}
from tblib import pickling_support
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP
pickling_support.install() # install for all modules imported so far
@pickling_support.install … class CustomError(Exception): … pass
```
Eventual subclasses of
CustomErrorwill need to be decorated again. -
Invoke
pickling_support.install()after all modules have been imported and all Exception subclasses have been declared``` {.sourceCode .python}
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP from tblib import pickling_support
Declare your own custom Exceptions
class CustomError(Exception): … pass
Finally, install tblib
pickling_support.install()
```
-
Selectively install tblib for Exception instances just before they are pickled
``` {.sourceCode .python} pickling_support.install(
, [Exception instance], ...) ```
The above will install tblib pickling for all listed exceptions as well as any other exceptions in their exception chains.
For example, one could write a wrapper to be used with ProcessPoolExecutor, Dask.distributed, or similar libraries:
>>> from tblib import pickling_support
>>> def wrapper(func, *args, **kwargs):
... try:
... return func(*args, **kwargs)
... except Exception as e:
... pickling_support.install(e)
... raise
What if we have a local stack, does it show correctly ?
Yes it does:
>>> exc_info = pickle.loads(s3)
>>> def local_0():
... reraise(*exc_info)
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> local_2()
Traceback (most recent call last):
File "...doctest.py", line ..., in __run
compileflags, 1) in test.globs
File "<doctest README.rst[24]>", line 1, in <module>
local_2()
File "<doctest README.rst[23]>", line 2, in local_2
local_1()
File "<doctest README.rst[22]>", line 2, in local_1
local_0()
File "<doctest README.rst[21]>", line 2, in local_0
reraise(*exc_info)
File "<doctest README.rst[11]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
It also supports more contrived scenarios
Like tracebacks with syntax errors:
>>> from tblib import Traceback
>>> from examples import bad_syntax
>>> try:
... bad_syntax()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[58]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[57]>", line 2, in <module>
bad_syntax()
File "...tests...examples.py", line 18, in bad_syntax
import badsyntax
File "...tests...badsyntax.py", line 5
is very bad
^
SyntaxError: invalid syntax
Or other import failures:
>>> from examples import bad_module
>>> try:
... bad_module()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[61]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[60]>", line 2, in <module>
bad_module()
File "...tests...examples.py", line 23, in bad_module
import badmodule
File "...tests...badmodule.py", line 3, in <module>
raise Exception("boom!")
Exception: boom!
Or a traceback that's caused by exceeding the recursion limit (here we're forcing the type and value to have consistency across platforms):
>>> def f(): f()
>>> try:
... f()
... except RuntimeError:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(RuntimeError, RuntimeError("maximum recursion depth exceeded"), tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
...
RuntimeError: maximum recursion depth exceeded
Reference
tblib.Traceback
It is used by the pickling_support. You can use it too if you want
more flexibility:
>>> from tblib import Traceback
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.to_dict
You can use the to_dict method and the from_dict classmethod to
convert a Traceback into and from a dictionary serializable by the
stdlib json.JSONDecoder:
>>> import json
>>> from pprint import pprint
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
... tb_dict = tb.to_dict()
... pprint(tb_dict)
{'tb_frame': {'f_code': {'co_filename': '<doctest README.rst[...]>',
'co_name': '<module>'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 5},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_2'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_1'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_0'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': None}}}}
tblib.Traceback.from_dict
Building on the previous example:
>>> tb_json = json.dumps(tb_dict)
>>> tb = Traceback.from_dict(json.loads(tb_json))
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.from_string
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
If you use the strict=False option then parsing is a bit more lax:
>>> tb = Traceback.from_string("""
... File "bogus.py", line 123, in bogus
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """, strict=False)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "bogus.py", line 123, in bogus
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
tblib.decorators.return_error
>>> from tblib.decorators import return_error
>>> inner_2r = return_error(inner_2)
>>> e = inner_2r()
>>> e
<tblib.decorators.Error object at ...>
>>> e.reraise()
Traceback (most recent call last):
...
File "<doctest README.rst[26]>", line 1, in <module>
e.reraise()
File "...tblib...decorators.py", line 19, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 25, in return_exceptions_wrapper
return func(*args, **kwargs)
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
How's this useful? Imagine you're using multiprocessing like this:
# Note that Python 3.4 and later will show the remote traceback (but as a string sadly) so we skip testing this.
>>> import traceback
>>> from multiprocessing import Pool
>>> from examples import func_a
>>> pool = Pool() # doctest: +SKIP
>>> try: # doctest: +SKIP
... for i in pool.map(func_a, range(5)):
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
for i in pool.map(func_a, range(5)):
File "...multiprocessing...pool.py", line ..., in map
...
File "...multiprocessing...pool.py", line ..., in get
...
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate() # doctest: +SKIP
Not very useful is it? Let's sort this out:
>>> from tblib.decorators import apply_with_return_error, Error
>>> from itertools import repeat
>>> pool = Pool()
>>> try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 4, in <module>
i.reraise()
File "...tblib...decorators.py", line ..., in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line ..., in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line ..., in apply_with_return_error
return args[0](*args[1:])
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate()
Much better !
What if we have a local call stack ?
>>> def local_0():
... pool = Pool()
... try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... finally:
... pool.close()
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> try:
... local_2()
... except:
... print(traceback.format_exc())
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
local_2()
File "<doctest README.rst[...]>", line 2, in local_2
local_1()
File "<doctest README.rst[...]>", line 2, in local_1
local_0()
File "<doctest README.rst[...]>", line 6, in local_0
i.reraise()
File "...tblib...decorators.py", line 20, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 27, in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line 47, in apply_with_return_error
return args[0](*args[1:])
File "...tests...examples.py", line 2, in func_a
func_b()
File "...tests...examples.py", line 6, in func_b
func_c()
File "...tests...examples.py", line 10, in func_c
func_d()
File "...tests...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
Other weird stuff
Clearing traceback works (Python 3.4 and up):
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> import traceback, sys
>>> if sys.version_info > (3, 4):
... traceback.clear_frames(tb)
Credits
- mitsuhiko/jinja2 for figuring a way to create traceback objects.
CHANGELOG
Changelog
3.0.0 (2023-10-22)
- Added support for
__context__,__suppress_context__and__notes__. Contributed by Tim Maxwell in #72. - Added the
get_localsargument totblib.pickling_support.install(),tblib.Tracebackandtblib.Frame. Fixes #41. - Dropped support for now-EOL Python 3.7 and added 3.12 in the test grid.
2.0.0 (2023-06-22)
- Removed support for legacy Pythons (2.7 and 3.6) and added Python 3.11 in the test grid.
- Some cleanups and refactors (mostly from ruff).
1.7.0 (2020-07-24)
- Add more attributes to
FrameandCodeobjects for pytest compatibility. Contributed by Ivanq in #58.
1.6.0 (2019-12-07)
- When pickling an Exception, also pickle its traceback and the
Exception chain (
raise ... from ...). Contributed by Guido Imperiale in #53.
1.5.0 (2019-10-23)
- Added support for Python 3.8. Contributed by Victor Stinner in #42.
- Removed support for end of life Python 3.4.
- Few CI improvements and fixes.
1.4.0 (2019-05-02)
- Removed support for end of life Python 3.3.
- Fixed tests for Python 3.7. Contributed by Elliott Sales de Andrade in #36.
- Fixed compatibility issue with Twised
(
twisted.python.failure.Failureexpected aco_codeattribute).
1.3.2 (2017-04-09)
- Add support for PyPy3.5-5.7.1-beta. Previously
AttributeError: 'Frame' object has no attribute 'clear'could be raised. See PyPy issue #2532.
1.3.1 (2017-03-27)
- Fixed handling for tracebacks due to exceeding the recursion limit. Fixes #15.
1.3.0 (2016-03-08)
- Added
Traceback.from_string.
1.2.0 (2015-12-18)
- Fixed handling for tracebacks from generators and other internal improvements and optimizations. Contributed by DRayX in #10 and #11.
1.1.0 (2015-07-27)
- Added support for Python 2.6. Contributed by Arcadiy Ivanov in #8.
1.0.0 (2015-03-30)
- Added
to_dictmethod andfrom_dictclassmethod on Tracebacks. Contributed by beckjake in #5.
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Third-Party Package
This third-party package's source repository does not contain a package manifest. Instead, its package manifest is stored in its release repository. In order to build this package from source in a Catkin workspace, please download its package manifest.Package Summary
| Tags | No category tags. |
| Version | 1.2.0 |
| License | BSD |
| Build type | CATKIN |
| Use | RECOMMENDED |
Repository Summary
| Checkout URI | https://github.com/ionelmc/python-tblib.git |
| VCS Type | git |
| VCS Version | master |
| Last Updated | 2024-05-02 |
| Dev Status | MAINTAINED |
| CI status | No Continuous Integration |
| Released | RELEASED |
| Tags | No category tags. |
| Contributing |
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Package Description
Traceback fiddling library. Allows you to pickle tracebacks.
Additional Links
Maintainers
- AlexV
Authors
- Ionel Cristian Mărieș
Overview
+———————————–+———————————–+
| docs | Documentation Status |
+———————————–+———————————–+
| tests | | ![GitHub Actions Build Status] |
| | (https://github.com/ionelmc/pytho |
| | n-tblib/actions/workflows/github- |
| | actions.yml/badge.svg) |
| | | Coverage Status |
+———————————–+———————————–+
| package | | ![PyPI Package latest release] |
| | (https://img.shields.io/pypi/v/tb |
| | lib.svg) |
| | PyPI Wheel |
| | Supported versions |
| | Supported implementations |
| | | |
+———————————–+———————————–+
Serialization library for Exceptions and Tracebacks.
- Free software: BSD license
It allows you to:
- Pickle tracebacks and raise exceptions with pickled tracebacks in different processes. This allows better error handling when running code over multiple processes (imagine multiprocessing, billiard, futures, celery etc).
- Create traceback objects from strings (the
from_stringmethod). No pickling is used. - Serialize tracebacks to/from plain dicts (the
from_dictandto_dictmethods). No pickling is used. - Raise the tracebacks created from the aforementioned sources.
- Pickle an Exception together with its traceback and exception chain
(
raise ... from ...) (Python 3 only)
Again, note that using the pickle support is completely optional. You are solely responsible for security problems should you decide to use the pickle support.
Installation
pip install tblib
Documentation
::: {.contents local=””} :::
Pickling tracebacks
Note: The traceback objects that come out are stripped of some attributes (like variables). But you'll be able to raise exceptions with those tracebacks or print them - that should cover 99% of the usecases.
>>> from tblib import pickling_support
>>> pickling_support.install()
>>> import pickle, sys
>>> def inner_0():
... raise Exception('fail')
...
>>> def inner_1():
... inner_0()
...
>>> def inner_2():
... inner_1()
...
>>> try:
... inner_2()
... except:
... s1 = pickle.dumps(sys.exc_info())
...
>>> len(s1) > 1
True
>>> try:
... inner_2()
... except:
... s2 = pickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s2) > 1
True
>>> try:
... import cPickle
... except ImportError:
... import pickle as cPickle
>>> try:
... inner_2()
... except:
... s3 = cPickle.dumps(sys.exc_info(), protocol=pickle.HIGHEST_PROTOCOL)
...
>>> len(s3) > 1
True
Unpickling tracebacks
>>> pickle.loads(s1)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s2)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
>>> pickle.loads(s3)
(<...Exception'>, Exception('fail'...), <traceback object at ...>)
Raising
>>> from six import reraise
>>> reraise(*pickle.loads(s1))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s2))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
>>> reraise(*pickle.loads(s3))
Traceback (most recent call last):
...
File "<doctest README.rst[14]>", line 1, in <module>
reraise(*pickle.loads(s2))
File "<doctest README.rst[8]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
Pickling Exceptions together with their traceback and chain (Python 3 only)
>>> try: # doctest: +SKIP
... try:
... 1 / 0
... except Exception as e:
... raise Exception("foo") from e
... except Exception as e:
... s = pickle.dumps(e)
>>> raise pickle.loads(s) # doctest: +SKIP
Traceback (most recent call last):
File "<doctest README.rst[16]>", line 3, in <module>
1 / 0
ZeroDivisionError: division by zero
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<doctest README.rst[17]>", line 1, in <module>
raise pickle.loads(s)
File "<doctest README.rst[16]>", line 5, in <module>
raise Exception("foo") from e
Exception: foo
BaseException subclasses defined after calling
pickling_support.install() will not retain their traceback and
exception chain pickling. To cover custom Exceptions, there are three
options:
-
Use
@pickling_support.installas a decorator for each custom Exception``` {.sourceCode .python}
from tblib import pickling_support
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP
pickling_support.install() # install for all modules imported so far
@pickling_support.install … class CustomError(Exception): … pass
```
Eventual subclasses of
CustomErrorwill need to be decorated again. -
Invoke
pickling_support.install()after all modules have been imported and all Exception subclasses have been declared``` {.sourceCode .python}
Declare all imports of your package’s dependencies
import numpy # doctest: +SKIP from tblib import pickling_support
Declare your own custom Exceptions
class CustomError(Exception): … pass
Finally, install tblib
pickling_support.install()
```
-
Selectively install tblib for Exception instances just before they are pickled
``` {.sourceCode .python} pickling_support.install(
, [Exception instance], ...) ```
The above will install tblib pickling for all listed exceptions as well as any other exceptions in their exception chains.
For example, one could write a wrapper to be used with ProcessPoolExecutor, Dask.distributed, or similar libraries:
>>> from tblib import pickling_support
>>> def wrapper(func, *args, **kwargs):
... try:
... return func(*args, **kwargs)
... except Exception as e:
... pickling_support.install(e)
... raise
What if we have a local stack, does it show correctly ?
Yes it does:
>>> exc_info = pickle.loads(s3)
>>> def local_0():
... reraise(*exc_info)
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> local_2()
Traceback (most recent call last):
File "...doctest.py", line ..., in __run
compileflags, 1) in test.globs
File "<doctest README.rst[24]>", line 1, in <module>
local_2()
File "<doctest README.rst[23]>", line 2, in local_2
local_1()
File "<doctest README.rst[22]>", line 2, in local_1
local_0()
File "<doctest README.rst[21]>", line 2, in local_0
reraise(*exc_info)
File "<doctest README.rst[11]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
It also supports more contrived scenarios
Like tracebacks with syntax errors:
>>> from tblib import Traceback
>>> from examples import bad_syntax
>>> try:
... bad_syntax()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[58]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[57]>", line 2, in <module>
bad_syntax()
File "...tests...examples.py", line 18, in bad_syntax
import badsyntax
File "...tests...badsyntax.py", line 5
is very bad
^
SyntaxError: invalid syntax
Or other import failures:
>>> from examples import bad_module
>>> try:
... bad_module()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[61]>", line 1, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[60]>", line 2, in <module>
bad_module()
File "...tests...examples.py", line 23, in bad_module
import badmodule
File "...tests...badmodule.py", line 3, in <module>
raise Exception("boom!")
Exception: boom!
Or a traceback that's caused by exceeding the recursion limit (here we're forcing the type and value to have consistency across platforms):
>>> def f(): f()
>>> try:
... f()
... except RuntimeError:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(RuntimeError, RuntimeError("maximum recursion depth exceeded"), tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
File "<doctest README.rst[32]>", line 1, in f
def f(): f()
...
RuntimeError: maximum recursion depth exceeded
Reference
tblib.Traceback
It is used by the pickling_support. You can use it too if you want
more flexibility:
>>> from tblib import Traceback
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
...
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.to_dict
You can use the to_dict method and the from_dict classmethod to
convert a Traceback into and from a dictionary serializable by the
stdlib json.JSONDecoder:
>>> import json
>>> from pprint import pprint
>>> try:
... inner_2()
... except:
... et, ev, tb = sys.exc_info()
... tb = Traceback(tb)
... tb_dict = tb.to_dict()
... pprint(tb_dict)
{'tb_frame': {'f_code': {'co_filename': '<doctest README.rst[...]>',
'co_name': '<module>'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 5},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_2'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_1'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': {'tb_frame': {'f_code': {'co_filename': ...,
'co_name': 'inner_0'},
'f_globals': {'__name__': '__main__'},
'f_lineno': 2},
'tb_lineno': 2,
'tb_next': None}}}}
tblib.Traceback.from_dict
Building on the previous example:
>>> tb_json = json.dumps(tb_dict)
>>> tb = Traceback.from_dict(json.loads(tb_json))
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[21]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "<doctest README.rst[21]>", line 2, in <module>
inner_2()
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
tblib.Traceback.from_string
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
If you use the strict=False option then parsing is a bit more lax:
>>> tb = Traceback.from_string("""
... File "bogus.py", line 123, in bogus
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """, strict=False)
>>> reraise(et, ev, tb.as_traceback())
Traceback (most recent call last):
...
File "<doctest README.rst[42]>", line 6, in <module>
reraise(et, ev, tb.as_traceback())
File "bogus.py", line 123, in bogus
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: fail
tblib.decorators.return_error
>>> from tblib.decorators import return_error
>>> inner_2r = return_error(inner_2)
>>> e = inner_2r()
>>> e
<tblib.decorators.Error object at ...>
>>> e.reraise()
Traceback (most recent call last):
...
File "<doctest README.rst[26]>", line 1, in <module>
e.reraise()
File "...tblib...decorators.py", line 19, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 25, in return_exceptions_wrapper
return func(*args, **kwargs)
File "<doctest README.rst[5]>", line 2, in inner_2
inner_1()
File "<doctest README.rst[4]>", line 2, in inner_1
inner_0()
File "<doctest README.rst[3]>", line 2, in inner_0
raise Exception('fail')
Exception: fail
How's this useful? Imagine you're using multiprocessing like this:
# Note that Python 3.4 and later will show the remote traceback (but as a string sadly) so we skip testing this.
>>> import traceback
>>> from multiprocessing import Pool
>>> from examples import func_a
>>> pool = Pool() # doctest: +SKIP
>>> try: # doctest: +SKIP
... for i in pool.map(func_a, range(5)):
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
for i in pool.map(func_a, range(5)):
File "...multiprocessing...pool.py", line ..., in map
...
File "...multiprocessing...pool.py", line ..., in get
...
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate() # doctest: +SKIP
Not very useful is it? Let's sort this out:
>>> from tblib.decorators import apply_with_return_error, Error
>>> from itertools import repeat
>>> pool = Pool()
>>> try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... except:
... print(traceback.format_exc())
...
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 4, in <module>
i.reraise()
File "...tblib...decorators.py", line ..., in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line ..., in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line ..., in apply_with_return_error
return args[0](*args[1:])
File "...examples.py", line 2, in func_a
func_b()
File "...examples.py", line 6, in func_b
func_c()
File "...examples.py", line 10, in func_c
func_d()
File "...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
>>> pool.terminate()
Much better !
What if we have a local call stack ?
>>> def local_0():
... pool = Pool()
... try:
... for i in pool.map(apply_with_return_error, zip(repeat(func_a), range(5))):
... if isinstance(i, Error):
... i.reraise()
... else:
... print(i)
... finally:
... pool.close()
...
>>> def local_1():
... local_0()
...
>>> def local_2():
... local_1()
...
>>> try:
... local_2()
... except:
... print(traceback.format_exc())
Traceback (most recent call last):
File "<doctest README.rst[...]>", line 2, in <module>
local_2()
File "<doctest README.rst[...]>", line 2, in local_2
local_1()
File "<doctest README.rst[...]>", line 2, in local_1
local_0()
File "<doctest README.rst[...]>", line 6, in local_0
i.reraise()
File "...tblib...decorators.py", line 20, in reraise
reraise(self.exc_type, self.exc_value, self.traceback)
File "...tblib...decorators.py", line 27, in return_exceptions_wrapper
return func(*args, **kwargs)
File "...tblib...decorators.py", line 47, in apply_with_return_error
return args[0](*args[1:])
File "...tests...examples.py", line 2, in func_a
func_b()
File "...tests...examples.py", line 6, in func_b
func_c()
File "...tests...examples.py", line 10, in func_c
func_d()
File "...tests...examples.py", line 14, in func_d
raise Exception("Guessing time !")
Exception: Guessing time !
<BLANKLINE>
Other weird stuff
Clearing traceback works (Python 3.4 and up):
>>> tb = Traceback.from_string("""
... File "skipped.py", line 123, in func_123
... Traceback (most recent call last):
... File "tests/examples.py", line 2, in func_a
... func_b()
... File "tests/examples.py", line 6, in func_b
... func_c()
... File "tests/examples.py", line 10, in func_c
... func_d()
... File "tests/examples.py", line 14, in func_d
... Doesn't: matter
... """)
>>> import traceback, sys
>>> if sys.version_info > (3, 4):
... traceback.clear_frames(tb)
Credits
- mitsuhiko/jinja2 for figuring a way to create traceback objects.
CHANGELOG
Changelog
3.0.0 (2023-10-22)
- Added support for
__context__,__suppress_context__and__notes__. Contributed by Tim Maxwell in #72. - Added the
get_localsargument totblib.pickling_support.install(),tblib.Tracebackandtblib.Frame. Fixes #41. - Dropped support for now-EOL Python 3.7 and added 3.12 in the test grid.
2.0.0 (2023-06-22)
- Removed support for legacy Pythons (2.7 and 3.6) and added Python 3.11 in the test grid.
- Some cleanups and refactors (mostly from ruff).
1.7.0 (2020-07-24)
- Add more attributes to
FrameandCodeobjects for pytest compatibility. Contributed by Ivanq in #58.
1.6.0 (2019-12-07)
- When pickling an Exception, also pickle its traceback and the
Exception chain (
raise ... from ...). Contributed by Guido Imperiale in #53.
1.5.0 (2019-10-23)
- Added support for Python 3.8. Contributed by Victor Stinner in #42.
- Removed support for end of life Python 3.4.
- Few CI improvements and fixes.
1.4.0 (2019-05-02)
- Removed support for end of life Python 3.3.
- Fixed tests for Python 3.7. Contributed by Elliott Sales de Andrade in #36.
- Fixed compatibility issue with Twised
(
twisted.python.failure.Failureexpected aco_codeattribute).
1.3.2 (2017-04-09)
- Add support for PyPy3.5-5.7.1-beta. Previously
AttributeError: 'Frame' object has no attribute 'clear'could be raised. See PyPy issue #2532.
1.3.1 (2017-03-27)
- Fixed handling for tracebacks due to exceeding the recursion limit. Fixes #15.
1.3.0 (2016-03-08)
- Added
Traceback.from_string.
1.2.0 (2015-12-18)
- Fixed handling for tracebacks from generators and other internal improvements and optimizations. Contributed by DRayX in #10 and #11.
1.1.0 (2015-07-27)
- Added support for Python 2.6. Contributed by Arcadiy Ivanov in #8.
1.0.0 (2015-03-30)
- Added
to_dictmethod andfrom_dictclassmethod on Tracebacks. Contributed by beckjake in #5.
Wiki Tutorials
This package does not provide any links to tutorials in it's rosindex metadata.
You can check on the ROS Wiki Tutorials page for the package.
Dependant Packages
| Name | Deps |
|---|---|
| rostful |
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