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Posted to dev@qpid.apache.org by "Robbie Gemmell (Jira)" <ji...@apache.org> on 2021/09/15 12:00:18 UTC
[jira] [Commented] (PROTON-2432) Proton crashes because of a
concurrency failure in collector->pool
[ https://issues.apache.org/jira/browse/PROTON-2432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17415466#comment-17415466 ]
Robbie Gemmell commented on PROTON-2432:
----------------------------------------
Most of proton is expressly single threaded, to be used by a single (container) thread at a time, so the obvious first questions for me would be is this one of those areas (I think its the transport/connection collector, which I would expect is), and if so what is causing the concurrency (no idea).
Before someone with a clue about these bits (not me) comes along, perhaps see if you can determine whether its something your application is doing to introduce unexpected concurrency, or if not then maybe either provide a minimal reproducer that fails for you, or simply more details on what it is thats actually being done.
> Proton crashes because of a concurrency failure in collector->pool
> ------------------------------------------------------------------
>
> Key: PROTON-2432
> URL: https://issues.apache.org/jira/browse/PROTON-2432
> Project: Qpid Proton
> Issue Type: Bug
> Components: proton-c
> Affects Versions: proton-c-0.32.0
> Environment: RHEL 7
> Reporter: Jesse Hulsizer
> Priority: Major
>
> While running our application tests, our application crashes with many different backtraces that look similar to this...
> {noformat}
> #0 0x0000000000000000 in ?? ()
> #1 0x00007fc777579198 in pn_class_incref () from /usr/lib64/libqpid-proton.so.11
> #2 0x00007fc777587d8a in pn_collector_put () from /usr/lib64/libqpid-proton.so.11
> #3 0x00007fc7775887ea in ?? () from /usr/lib64/libqpid-proton.so.11
> #4 0x00007fc777588c7b in pn_transport_pending () from /usr/lib64/libqpid-proton.so.11
> #5 0x00007fc777588d9e in pn_transport_pop () from /usr/lib64/libqpid-proton.so.11
> #6 0x00007fc777599298 in ?? () from /usr/lib64/libqpid-proton.so.11
> #7 0x00007fc77759a784 in ?? () from /usr/lib64/libqpid-proton.so.11
> #8 0x00007fc7773236f0 in proton::container::impl::thread() () from /usr/lib64/libqpid-proton-cpp.so.12
> #9 0x00007fc7760b2470 in ?? () from /usr/lib64/libstdc++.so.6
> #10 0x00007fc776309aa1 in start_thread () from /lib64/libpthread.so.0
> #11 0x00007fc7758b6bdd in clone () from /lib64/libc.so.6{noformat}
> Using gdb to probe one of the backtraces show that the collector->pool size is -1... (seen here as 18446744073709551615)
> {noformat}
> (gdb) p *collector $1 = \{pool = 0x7fa7182de180, head = 0x7fa7182de250, tail = 0x7fa7182b8b90, prev = 0x7fa7182ea010, freed = false}
> (gdb) p collector->pool $2 = (pn_list_t *) 0x7fa7182de180 (gdb) p *collector->pool $3 = \{clazz = 0x7fa74eb7c000, capacity = 16, size = 18446744073709551615, elements = 0x7fa7182de1b0}{noformat}
> The proton code was marked up with print statements which show that two threads were accessing the collector->pool data structure at the same time...
> {noformat}
> 7b070700: pn_list_pop index 0 list->0x7fec401e0b70 value->0x7fec3c728a10
> 4ffff700:pn_list_add index 1 size 2list->0x7fec401e0b70 value->0x7fec402095b0
> 7b070700: pn_list_pop size 1 list->0x7fec401e0b70
> 4ffff700: pn_list_pop size 1 list->0x7fec401e0b70
> 7b070700: pn_list_pop index 0 list->0x7fec401e0b70 value->0x7fec3c728a10
> 4ffff700: pn_list_pop index 0 list->0x7fec401e0b70 value->0x7fec3c728a10{noformat}
> The hex number on the far left is the thread id. As can be seen in the last two lines, two threads are popping from the collector->pool simultaneously. This produces the -1 size as seen up above
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