Taskflow

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Taskflow helps you quickly write high-performance task-parallel programs with high programming productivity. It is faster, more expressive, fewer lines of code, and easier for drop-in integration than many existing task programming libraries.

Start Your First Taskflow Program

The following program (simple.cpp) creates four tasks A, B, C, and D, where A runs before B and C, and D runs after B and C. When A finishes, B and C run in parallel. Try it live on Compiler Explorer!

#include <taskflow/taskflow.hpp>  // Taskflow is header-only

int main(){
  
  tf::Executor executor;
  tf::Taskflow taskflow;

  auto [A, B, C, D] = taskflow.emplace(  // create four tasks
    [] () { std::cout << "TaskA\n"; },
    [] () { std::cout << "TaskB\n"; },
    [] () { std::cout << "TaskC\n"; },
    [] () { std::cout << "TaskD\n"; } 
  );                                  
                                      
  A.precede(B, C);  // A runs before B and C
  D.succeed(B, C);  // D runs after  B and C
                                      
  executor.run(taskflow).wait(); 

  return 0;
}

Taskflow is header-only and there is no struggle with installation. To compile the program, clone the Taskflow project and tell the compiler to include the headers under taskflow/.

~$ git clone https://github.com/taskflow/taskflow.git  # clone it only once
~$ g++ -std=c++20 simple.cpp -I taskflow/ -O2 -pthread -o simple
~$ ./simple
TaskA
TaskC 
TaskB 
TaskD

Taskflow comes with a built-in profiler, TFProf, for you to profile and visualize taskflow programs in an easy-to-use web-based interface.

# run the program with the environment variable TF_ENABLE_PROFILER enabled
~$ TF_ENABLE_PROFILER=simple.tfp ./simple
# drag the simple.tfp file to https://taskflow.github.io/tfprof/

Create a Subflow Graph

Taskflow supports recursive tasking for you to create a subflow graph from the execution of a task to perform recursive parallelism. The following program spawns a task dependency graph parented at task B.

tf::Task A = taskflow.emplace([](){}).name("A");  
tf::Task C = taskflow.emplace([](){}).name("C");  
tf::Task D = taskflow.emplace([](){}).name("D");  

tf::Task B = taskflow.emplace([] (tf::Subflow& subflow) { // subflow task B
  tf::Task B1 = subflow.emplace([](){}).name("B1");  
  tf::Task B2 = subflow.emplace([](){}).name("B2");  
  tf::Task B3 = subflow.emplace([](){}).name("B3");  
  B3.succeed(B1, B2);  // B3 runs after B1 and B2
}).name("B");

A.precede(B, C);  // A runs before B and C
D.succeed(B, C);  // D runs after  B and C

Integrate Control Flow into a Task Graph

Taskflow supports conditional tasking for you to make rapid control-flow decisions across dependent tasks to implement cycles and conditions in an end-to-end task graph.

```cpp tf::Task init = taskflow.emplace({}).name(“init”); tf::Task stop = taskflow.emplace({}).name(“stop”);

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