From f1699cd4c1b475a3e583c8975317df06907dcf8b Mon Sep 17 00:00:00 2001 From: Georg Brandl Date: Sat, 23 Feb 2008 23:25:26 +0000 Subject: Document import ./. threading issues. #1720705. --- Doc/library/thread.rst | 6 +++++- Doc/library/threading.rst | 7 +++++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/Doc/library/thread.rst b/Doc/library/thread.rst index b0e55ea..968ebf1 100644 --- a/Doc/library/thread.rst +++ b/Doc/library/thread.rst @@ -150,6 +150,11 @@ In addition to these methods, lock objects can also be used via the exception will be received by an arbitrary thread. (When the :mod:`signal` module is available, interrupts always go to the main thread.) +* The import machinery is not thread safe. In general, an import may not + have the side effect of importing a module, and only the main thread + should import modules. Imports within or caused by a thread other than + the main thread isn't safe. + * Calling :func:`sys.exit` or raising the :exc:`SystemExit` exception is equivalent to calling :func:`exit`. @@ -170,4 +175,3 @@ In addition to these methods, lock objects can also be used via the * When the main thread exits, it does not do any of its usual cleanup (except that :keyword:`try` ... :keyword:`finally` clauses are honored), and the standard I/O files are not flushed. - diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst index 077ae01..73ede7b 100644 --- a/Doc/library/threading.rst +++ b/Doc/library/threading.rst @@ -562,6 +562,13 @@ the :meth:`setDaemon` method and retrieved with the :meth:`isDaemon` method. There is a "main thread" object; this corresponds to the initial thread of control in the Python program. It is not a daemon thread. +.. warning:: + + The import machinery is not thread safe. In general, an import may not + have the side effect of importing a module, and only the main thread + should import modules. Imports within or caused by a thread other than + the main thread isn't safe. + There is the possibility that "dummy thread objects" are created. These are thread objects corresponding to "alien threads", which are threads of control started outside the threading module, such as directly from C code. Dummy -- cgit v0.12