Mercurial
diff third_party/libuv/docs/src/threadpool.rst @ 160:948de3f54cea
[ThirdParty] Added libuv
| author | June Park <parkjune1995@gmail.com> |
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| date | Wed, 14 Jan 2026 19:39:52 -0800 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/third_party/libuv/docs/src/threadpool.rst Wed Jan 14 19:39:52 2026 -0800 @@ -0,0 +1,74 @@ + +.. _threadpool: + +Thread pool work scheduling +=========================== + +libuv provides a threadpool which can be used to run user code and get notified +in the loop thread. This thread pool is internally used to run all file system +operations, as well as getaddrinfo and getnameinfo requests. + +Its default size is 4, but it can be changed at startup time by setting the +``UV_THREADPOOL_SIZE`` environment variable to any value (the absolute maximum +is 1024). + +.. versionchanged:: 1.30.0 the maximum UV_THREADPOOL_SIZE allowed was increased from 128 to 1024. + +.. versionchanged:: 1.45.0 threads now have an 8 MB stack instead of the + (sometimes too low) platform default. + +.. versionchanged:: 1.50.0 threads now have a default name of libuv-worker. + +The threadpool is global and shared across all event loops. When a particular +function makes use of the threadpool (e.g. when using :c:func:`uv_queue_work`) +libuv preallocates and initializes the maximum number of threads allowed by +``UV_THREADPOOL_SIZE``. More threads usually means more throughput but a higher +memory footprint. Thread stacks grow lazily on most platforms though. + +.. note:: + Note that even though a global thread pool which is shared across all events + loops is used, the functions are not thread safe. + + +Data types +---------- + +.. c:type:: uv_work_t + + Work request type. + +.. c:type:: void (*uv_work_cb)(uv_work_t* req) + + Callback passed to :c:func:`uv_queue_work` which will be run on the thread + pool. + +.. c:type:: void (*uv_after_work_cb)(uv_work_t* req, int status) + + Callback passed to :c:func:`uv_queue_work` which will be called on the loop + thread after the work on the threadpool has been completed. If the work + was cancelled using :c:func:`uv_cancel` `status` will be ``UV_ECANCELED``. + + +Public members +^^^^^^^^^^^^^^ + +.. c:member:: uv_loop_t* uv_work_t.loop + + Loop that started this request and where completion will be reported. + Readonly. + +.. seealso:: The :c:type:`uv_req_t` members also apply. + + +API +--- + +.. c:function:: int uv_queue_work(uv_loop_t* loop, uv_work_t* req, uv_work_cb work_cb, uv_after_work_cb after_work_cb) + + Initializes a work request which will run the given `work_cb` in a thread + from the threadpool. Once `work_cb` is completed, `after_work_cb` will be + called on the loop thread. + + This request can be cancelled with :c:func:`uv_cancel`. + +.. seealso:: The :c:type:`uv_req_t` API functions also apply.