[GitHub] [arrow] framlog commented on a change in pull request #12358: ARROW-15593: [C++] Make after-fork ThreadPool reinitialization thread-safe

[GitBox <gi...@apache.org>]

framlog commented on a change in pull request #12358:
URL: https://github.com/apache/arrow/pull/12358#discussion_r801187688



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File path: cpp/src/arrow/util/mutex.cc
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@@ -50,5 +55,31 @@ Mutex::Guard Mutex::Lock() {
 
 Mutex::Mutex() : impl_(new Impl, [](Impl* impl) { delete impl; }) {}
 
+#ifndef _WIN32
+namespace {
+
+struct AfterForkState {
+  // A global instance that will also register the atfork handler when
+  // constructed.
+  static AfterForkState instance;
+
+  // The mutex may be used at shutdown, so make it eternal.
+  // The leak (only in child processes) is a small price to pay for robustness.
+  Mutex* mutex = nullptr;

Review comment:
       nit: Maybe it's not trivial when working with multiprocessing in Python. Why not use a `unique_ptr` here?




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