初始化仓库

Linux_Hello/lib/libuv-v1.51.0/docs/src/threadpool.rst

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+
+.. _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.