Hi, I've been looking at the cause of a deadlock when running ra-test.exe with -fs-type=fsx (trunk version).
The most important findings are summed up here atm [1]. The issue was discussed with brane and danielsh on IRC (thanks for your time, once again). As far as my current understanding of the problem goes: the deadlock is caused by the fact that the apr_terminate() function registered in svn_cmdline_init() via the atexit-call is called after the termination of the threads which were created as part of the calls to apr_thread_pool_push() in svn_fs_x__batch_fsync_run(). This means that apr's thread counter (thd_cnt) is getting out of sync (since the apr-function thread_pool_func() is not executed) and then gets stuck in thread_pool_cleanup() (waiting for the already terminated threads to be terminated). To me it looks like svnserve's main-function already contains a safeguard against a corresponding issue, and calls apr_thread_pool_destroy(threads) (or was this a completely different scenario?). This however does not cover the threads created from svn_fs_x__batch_fsync_run(). Talking to danielsh and brane it became apparent to me that the issue might not be too obvious (in the end it might still be an issue on how I build SVN and therefore cause the atexit-registered apr_terminate() function to be called too late). It's also not fully clear to me at which exact point (in regards to registerd atexit()-calls) threads of the process are terminated if the process itself terminates. If indeed atexit()-registered functions get called after the threads are forcibly terminates (which to me it looks like it does atm) it might contradict the C(89/99) standard - see[2] 7.20.4.2/7.20.4.3. On the other side this thread on stackoverflow [3] suggests it's simply undefined (by the standard) what comes first. As danielsh suggested, I'm planning to come up with a plain minimal repro app only based on APR demonstrating the problem, so to make it more obvious (and double check for myself) what the issue is about. Regards, Stefan [1] http://www.luke1410.de:8090/browse/MAXSVN-94 [2] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf [3] https://stackoverflow.com/questions/39655868/what-does-the-posix-standard-say-about-thread-stacks-in-atexit-handlers-what
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