Differences between version 5 and predecessor to the previous major change of PythonNotes.
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| Newer page: | version 5 | Last edited on Thursday, September 20, 2007 10:54:57 am | by JohnMcPherson | Revert |
| Older page: | version 4 | Last edited on Thursday, June 21, 2007 8:54:12 pm | by JohnMcPherson | Revert |
@@ -18,10 +18,12 @@
!!! threads
!! subprocess module
If you use the ''subprocess'' module to spawn a child in one of your threads and you are using locks, there is a possibility of a deadlock. See the discussion in the [python newsgroup|http://groups.google.com/group/comp.lang.python/browse_thread/thread/5fae8a453c95ae89/42f5c9f9215dbb1e#42f5c9f9215dbb1e]. Basically, python internally uses locks during imports, and you can fix it in this instance by moving the ''"from errno import ENOENT, ENOTDIR"'' line from the ''_execvpe'' function in the subprocess.py module up to the top, so that it doesn't happen after the fork(). This affects python 2.4 at least, not sure if it's fixed in 2.5.
+
+The ''subprocess'' module is also buggy if you have multiple threads using subprocess to create child processes. Basically, it isn't thread-safe when checking if a child has finished, and you occasionally get "<tt>~[Errno 10] No child processes</tt>" exceptions. See [mailing list thread|http://www.mail-archive.com/python-bugs-list@python.org/msg12685.html].
!! python-gtk
If you want to do ''thread.start_new_thread()'' from within an app using pygtk, you need to call ''gtk.gdk.threads_init()'' first, otherwise the gtk event loop will screw you up.
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CategoryProgramming, CategoryNotes
