Mercurial > cpython-lru_cache-weakref

diff Python/import.c @ 80451:bd853311ffe0

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Issue #15894: Document why we don't worry about re-acquiring the global import lock after forking.
author Brett Cannon <brett@python.org>
date Thu, 15 Nov 2012 21:39:36 -0500
parents ee0c0f1c1eb2
children 6eefe4d537b3
line wrap: on
line diff
--- a/Python/import.c	Thu Nov 15 16:16:45 2012 -0500
+++ b/Python/import.c	Thu Nov 15 21:39:36 2012 -0500
@@ -202,8 +202,11 @@
     if (import_lock_level > 1) {
         /* Forked as a side effect of import */
         long me = PyThread_get_thread_ident();
-        PyThread_acquire_lock(import_lock, 0);
-        /* XXX: can the previous line fail? */
+        /* The following could fail if the lock is already held, but forking as
+           a side-effect of an import is a) rare, b) nuts, and c) difficult to
+           do thanks to the lock only being held when doing individual module
+           locks per import. */
+        PyThread_acquire_lock(import_lock, NOWAIT_LOCK);
         import_lock_thread = me;
         import_lock_level--;
     } else {