Skip to content
The libdispatch Project, (a.k.a. Grand Central Dispatch), for concurrency on multicore hardware
C C++ Swift Objective-C CMake Objective-C++ Other
Branch: master
Clone or download
ktopley-apple Merge pull request #530 from compnerd/public-flags
build: make some linkage flags public
Latest commit c992dac Oct 1, 2019


Type Name Latest commit message Commit time
Failed to load latest commit information.
cmake build: add exports targets Sep 27, 2019
config Initial merge of darwin/libdispatch-1121 into GitHub master. Feb 19, 2019
dispatch semaphore: annotate fallthrough (NFC) Sep 24, 2019
libdispatch.xcodeproj Initial merge of darwin/libdispatch-1121 into GitHub master. Feb 19, 2019
man Merge libdispatch-1121 Dec 6, 2018
os Initial merge of darwin/libdispatch-1121 into GitHub master. Feb 19, 2019
private Merge pull request #460 from triplef/fix-cmake-private-install Mar 20, 2019
resolver Import libdispatch-500.1.5 Nov 9, 2015
src build: make some linkage flags public Sep 30, 2019
tests tests: fix -Werror,-Wimplicit-int-float-conversion Sep 24, 2019
tools Merge libdispatch-913.1.4 Jul 31, 2017
xcodeconfig Merge libdispatch-1121 Dec 6, 2018
xcodescripts Merge libdispatch-1121 Dec 6, 2018
.gitignore xcode / autoconf plumbing to select module.modulemap file Aug 12, 2016
.gitmodules implement pthread_workqueue within libdispatch May 25, 2017
.mailmap Add mailmap for git history. Apr 17, 2018
CMakeLists.txt build: add exports targets Sep 27, 2019 Add legal notice for pull requests and reference to contribution guid… Dec 5, 2015 build: support system installed BlocksRuntime Dec 6, 2018
LICENSE Update to the license Dec 18, 2015
PATCHES Merge pull request #390 from dingobye/redundant_access_modifier Dec 6, 2018 update README and INSTALL for libpwq removal May 19, 2017 SR-3237: Document libdispatch testsuite Nov 18, 2016

Grand Central Dispatch

Grand Central Dispatch (GCD or libdispatch) provides comprehensive support for concurrent code execution on multicore hardware.

libdispatch is currently available on all Darwin platforms. This project aims to make a modern version of libdispatch available on all other Swift platforms. To do this, we will implement as much of the portable subset of the API as possible, using the existing open source C implementation.

libdispatch on Darwin is a combination of logic in the xnu kernel alongside the user-space Library. The kernel has the most information available to balance workload across the entire system. As a first step, however, we believe it is useful to bring up the basic functionality of the library using user-space pthread primitives on Linux. Eventually, a Linux kernel module could be developed to support more informed thread scheduling.

Project Status

A port of libdispatch to Linux has been completed. On Linux, since Swift 3, swift-corelibs-libdispatch has been included in all Swift releases and is used by other swift-corelibs projects.

Opportunities to contribute and on-going work include:

  1. Develop a test suite for the Swift APIs of libdispatch.
  2. Enhance libdispatch as needed to support Swift language evolution and the needs of the other Core Libraries projects.

Build and Install

For detailed instructions on building and installing libdispatch, see


For detailed instructions on testing libdispatch, see

You can’t perform that action at this time.