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The 'libunifex' project is a prototype implementation of the C++ sender/receiver async programming model that is currently being considered for standardisation.

This project contains implementations of the following:

  • Schedulers
  • Timers
  • Asynchronous I/O (Linux w/ io_uring)
  • Algorithms that encapsulate certain concurrency patterns
  • Async streams
  • Cancellation
  • Coroutine integration


This project is still evolving and should be considered experimental in nature. No guarantee is made for API or ABI stability.

Build status

  • on Github Actions: GitHub Actions Status



A recent compiler that supports C++17 or later. Libunifex is known to work with the following compilers:

  • GCC, 11.x and later
  • Clang, 12.x and later
  • MSVC 2019.6 and later

This library also supports C++20 coroutines. You will need to compile with coroutine support enabled if you want to use the coroutine integrations. This generally means adding -std=c++2a or -fcoroutines-ts on Clang (see "Configuring" below).


The io_uring support on Linux requires a recent kernel version (5.6 or later).


The io_uring support depends on liburing:


windows_thread_pool executor requires Windows Vista or later.


This project can be built using CMake.

The examples below assume using the Ninja build system. You can use other build systems supported by CMake.


First generate the build files under the ./build subdirectory.

From the libunifex project root:

cmake -G Ninja -H. -Bbuild \

By default, this builds libunifex in C++17 without coroutines. If you want to turn on coroutines with clang, add:


To use libc++ with clang, which has coroutine support, you should also add:

      -DCMAKE_CXX_FLAGS:STRING=-stdlib=libc++ \

If you want to build libunifex as C++20, add:


Building Library + Running Tests

To build the library and tests.

From the ./build subdirectory run:


Once the tests have been built you can run them.

From the ./build subdirectory run:

ninja test


This project is made available under the Apache License, version 2.0, with LLVM Exceptions.

See LICENSE.txt for details.

See also:


C++ standardisation papers: