[Asterisk-code-review] chan sip: Don't unload module while TCP/TLS threads are stil... (asterisk[master])

[Michael Kuron]

Michael Kuron has posted comments on this change. ( https://gerrit.asterisk.org/4536 )

Change subject: chan_sip: Don't unload module while TCP/TLS threads are still running
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Patch Set 2:

I think I'm giving up on this. I needed to touch almost every line in unload_module and still couldn't get it right so that module unload chan_sip could be re-run after all threads had become unblocked and had terminated -- every time I fixed one thing, two others seemed to pop up. After all, it's not the most important bug to fix and these race conditions should be very rare (e.g. if a thread is blocked but doesn't respond to SIGURG, then magically becomes unstuck after the unload).

One thing I would like to keep is the second attempt at pthread_kill(thread, SIGURG) in the current patch set. That gives threads that hadn't reached their blocking syscall yet at the point the signal was first sent the opportunity to terminate properly. If I add a time limit of, say, 10 seconds to the while loop in line 35527, would that be acceptable to merge?

The problems that will remain are the leaking of deadlocked threads (unfixable at this level, but it's mainly a memory leak, therefore it doesn't matter during shutdown) and the crashing of threads that become unblocked after being blocked on a call that cannot return EINTR (messy to fix, see above, but probably very unlikely to occur; could crash Asterisk during shutdown if the thread becomes unstuck before shutdown is completed).

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Gerrit-MessageType: comment
Gerrit-Change-Id: I23a8abf9e8f73b57ff7ada61984b8506aea6cbde
Gerrit-PatchSet: 2
Gerrit-Project: asterisk
Gerrit-Branch: master
Gerrit-Owner: Michael Kuron <m.kuron at gmx.de>
Gerrit-Reviewer: Anonymous Coward #1000019
Gerrit-Reviewer: Corey Farrell <git at cfware.com>
Gerrit-Reviewer: Michael Kuron <m.kuron at gmx.de>
Gerrit-HasComments: No