libuv is a multi-platform support library with a focus on asynchronous I/O. It was primarily developed for use by Node.js, but it's also used by Luvit, Julia, pyuv, and others.
Full-featured event loop backed by epoll, kqueue, IOCP, event ports.
Asynchronous TCP and UDP sockets
Asynchronous DNS resolution
Asynchronous file and file system operations
File system events
ANSI escape code controlled TTY
IPC with socket sharing, using Unix domain sockets or named pipes (Windows)
High resolution clock
Threading and synchronization primitives
Starting with version 1.0.0 libuv follows the semantic versioning scheme. The API change and backwards compatibility rules are those indicated by SemVer. libuv will keep a stable ABI across major releases.
The ABI/API changes can be tracked here.
libuv is licensed under the MIT license. Check the LICENSE file. The documentation is licensed under the CC BY 4.0 license. Check the LICENSE-docs file.
Located in the docs/ subdirectory. It uses the Sphinx framework, which makes it possible to build the documentation in multiple formats.
Show different supported building options:
$ make help
Build documentation as HTML:
$ make html
Build documentation as HTML and live reload it when it changes (this requires sphinx-autobuild to be installed and is only supported on Unix):
$ make livehtml
Build documentation as man pages:
$ make man
Build documentation as ePub:
$ make epub
NOTE: Windows users need to use make.bat instead of plain 'make'.
Documentation can be browsed online here.
The tests and benchmarks also serve as API specification and usage examples.
These resources are not handled by libuv maintainers and might be out of date. Please verify it before opening new issues.
libuv can be downloaded either from the GitHub repository or from the downloads site.
Before verifying the git tags or signature files, importing the relevant keys is necessary. Key IDs are listed in the MAINTAINERS file, but are also available as git blob objects for easier use.
Importing a key the usual way:
$ gpg --keyserver pool.sks-keyservers.net --recv-keys AE9BC059
Importing a key from a git blob object:
$ git show pubkey-saghul | gpg --import
Git tags are signed with the developer's key, they can be verified as follows:
$ git verify-tag v1.6.1
Starting with libuv 1.7.0, the tarballs stored in the downloads site are signed and an accompanying signature file sit alongside each. Once both the release tarball and the signature file are downloaded, the file can be verified as follows:
$ gpg --verify libuv-1.7.0.tar.gz.sign
For UNIX-like platforms, including macOS, there are two build methods: autotools or CMake.
For Windows, CMake is the only supported build method and has the following prerequisites:
To build with autotools:
$ sh autogen.sh $ ./configure $ make $ make check $ make install
To build with CMake:
$ mkdir -p build $ (cd build && cmake .. -DBUILD_TESTING=ON) # generate project with tests $ cmake --build build # add `-j <n>` with cmake >= 3.12 # Run tests: $ (cd build && ctest -C Debug --output-on-failure) # Or manually run tests: $ build/uv_run_tests # shared library build $ build/uv_run_tests_a # static library build
To cross-compile with CMake (unsupported but generally works):
$ cmake ../.. \ -DCMAKE_SYSTEM_NAME=Windows \ -DCMAKE_SYSTEM_VERSION=6.1 \ -DCMAKE_C_COMPILER=i686-w64-mingw32-gcc
$ brew install --HEAD libuv
Note to OS X users:
Make sure that you specify the architecture you wish to build for in the "ARCHS" flag. You can specify more than one by delimiting with a space (e.g. "x86_64 i386").
Some tests are timing sensitive. Relaxing test timeouts may be necessary on slow or overloaded machines:
$ env UV_TEST_TIMEOUT_MULTIPLIER=2 build/uv_run_tests # 10s instead of 5s
The list of all tests is in
This invocation will cause the test driver to fork and execute
a child process:
$ build/uv_run_tests_a TEST_NAME
This invocation will cause the test driver to execute the test in the same process:
$ build/uv_run_tests_a TEST_NAME TEST_NAME
When running the test from within the test driver process
build/uv_run_tests_a TEST_NAME TEST_NAME), tools like gdb and valgrind
When running the test from a child of the test driver process
build/uv_run_tests_a TEST_NAME), use these tools in a fork-aware manner.
Use the follow-fork-mode setting:
$ gdb --args build/uv_run_tests_a TEST_NAME (gdb) set follow-fork-mode child ...
$ valgrind --trace-children=yes -v --tool=memcheck --leak-check=full --track-origins=yes --leak-resolution=high --show-reachable=yes --log-file=memcheck-%p.log build/uv_run_tests_a TEST_NAME
See the section on running tests.
The benchmark driver is
./uv_run_benchmarks_a and the benchmarks are
Check the SUPPORTED_PLATFORMS file.
AIX compilation using IBM XL C/C++ requires version 12.1 or greater.
AIX support for filesystem events requires the non-default IBM
package to be installed. This package provides the AIX Event Infrastructure
that is detected by
describes the package in more detail.
z/OS creates System V semaphores and message queues. These persist on the system after the process terminates unless the event loop is closed.
ipcrm command to manually clear up System V resources.
See the guidelines for contributing.