New submission from Péter Szabó <pts...@gmail.com>: According to http://docs.python.org/dev/library/signal.html , if I set up a signal handler in the main thread, and then have the signal delivered to the process, then the signal handler will be called in the main thread. The attached Python script I've written, however, doesn't work that way: sometimes the signal is completely lost, and the signal handler is not called.
Here is how it should work. The code has two threads: the main thread and the subthread. There is also a signal handler installed. The main thread is running select.select(), waiting for a filehandle to become readable. Then the subthread sends a signal to the process. The signal handler writes a byte to the pipe. The select wakes up raising 'Interrupted system call' because of the signal. I'm running Ubuntu Hardy on x86_64. With Python 2.4.5 and Python 2.5.2, sometimes the signal handler is not called, and the select continues waiting indefinitely. This is what I get on stdout in Python 2.4.5: main pid=8555 --- 0 A B S T U handler arg1=10 arg2=<frame object at 0x79ab40> select got="(4, 'Interrupted system call')" read str='W' --- 1 A B S T U This means that iteration 0 completed successfully: the signal handler got called, and the select raised 'Interrupted system call'. However, iteration 1 was stuck: the signal handler was never called, and the select waits indefinitely. The script seems to work in Python 2.4.3, but it hangs in iteration about 60000. ---------- components: Interpreter Core, Library (Lib) files: tsig.py messages: 82472 nosy: pts severity: normal status: open title: signal handler never gets called type: behavior versions: Python 2.4, Python 2.5 Added file: http://bugs.python.org/file13138/tsig.py _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue5315> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
