From e0e88b0483d73c925e8f1809d24031acd6bfdf01 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Charles-Fran=C3=A7ois=20Natali?= Date: Thu, 2 Feb 2012 19:57:19 +0100 Subject: [PATCH] Issue #13817: After fork(), reinit the ad-hoc TLS implementation earlier to fix a random deadlock when fork() is called in a multithreaded process in debug mode, and make PyOS_AfterFork() more robust. --- Lib/test/test_threading.py | 23 +++++++++++++++++++++++ Modules/signalmodule.c | 4 +++- 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py index bdb7f1453a1..e617fa1275a 100644 --- a/Lib/test/test_threading.py +++ b/Lib/test/test_threading.py @@ -635,6 +635,29 @@ class ThreadJoinOnShutdown(BaseTestCase): output = "end of worker thread\nend of main thread\n" self.assertScriptHasOutput(script, output) + @unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()") + def test_reinit_tls_after_fork(self): + # Issue #13817: fork() would deadlock in a multithreaded program with + # the ad-hoc TLS implementation. + + def do_fork_and_wait(): + # just fork a child process and wait it + pid = os.fork() + if pid > 0: + os.waitpid(pid, 0) + else: + os._exit(0) + + # start a bunch of threads that will fork() child processes + threads = [] + for i in range(16): + t = threading.Thread(target=do_fork_and_wait) + threads.append(t) + t.start() + + for t in threads: + t.join() + class ThreadingExceptionTests(BaseTestCase): # A RuntimeError should be raised if Thread.start() is called diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c index f306bba16f5..908c2ee9940 100644 --- a/Modules/signalmodule.c +++ b/Modules/signalmodule.c @@ -976,10 +976,12 @@ void PyOS_AfterFork(void) { #ifdef WITH_THREAD + /* PyThread_ReInitTLS() must be called early, to make sure that the TLS API + * can be called safely. */ + PyThread_ReInitTLS(); PyEval_ReInitThreads(); main_thread = PyThread_get_thread_ident(); main_pid = getpid(); _PyImport_ReInitLock(); - PyThread_ReInitTLS(); #endif }