On Fri, Mar 13, 2015 at 2:12 PM, Amit Langote <langote_amit...@lab.ntt.co.jp> wrote: > > On 13-03-2015 PM 05:32, Amit Langote wrote: > > On 12-03-2015 PM 11:46, Amit Kapila wrote: > >> [parallel_seqscan_v10.patch] > > > > There may be a bug in TupleQueueFunnelNext(). > > > > 1) I observed a hang with stack looking like: > > > > #0 0x00000039696df098 in poll () from /lib64/libc.so.6 > > #1 0x00000000006f1c6a in WaitLatchOrSocket (latch=0x7f29dc3c73b4, > > wakeEvents=1, sock=-1, timeout=0) at pg_latch.c:333 > > #2 0x00000000006f1aca in WaitLatch (latch=0x7f29dc3c73b4, wakeEvents=1, > > timeout=0) at pg_latch.c:197 > > #3 0x000000000065088b in TupleQueueFunnelNext (funnel=0x17b4a20, nowait=0 > > '\000', done=0x17ad481 "") at tqueue.c:269 > > #4 0x0000000000636cab in funnel_getnext (funnelstate=0x17ad3d0) at > > nodeFunnel.c:347 > > ... > > <snip> > > > > 2) In some cases, there can be a segmentation fault with stack looking like: > > > > #0 0x000000396968990a in memcpy () from /lib64/libc.so.6 > > #1 0x00000000006507e7 in TupleQueueFunnelNext (funnel=0x263c800, nowait=0 > > '\000', done=0x2633461 "") at tqueue.c:233 > > #2 0x0000000000636cab in funnel_getnext (funnelstate=0x26333b0) at > > nodeFunnel.c:347 > > #3 0x0000000000636901 in ExecFunnel (node=0x26333b0) at nodeFunnel.c:179 > > ... > > <snip> > > > > I could get rid of (1) and (2) with the attached fix. > > Hit send too soon! > > By the way, the bug seems to be exposed only with a certain pattern/sequence > of workers being detached (perhaps in immediate successive) whereby the > funnel->nextqueue remains incorrectly set. >
I think this can happen if funnel->nextqueue is greater than funnel->nqueues. Please see if attached patch fixes the issue, else could you share the scenario in more detail where you hit this issue. > The patch attached this time. > > By the way, when I have asserts enabled, I hit this compilation error: > > createplan.c: In function ‘create_partialseqscan_plan’: > createplan.c:1180: error: ‘Path’ has no member named ‘path’ > > I see following line there: > > Assert(best_path->path.parent->rtekind == RTE_RELATION); > Okay, will take care of this. Thanks. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
fix_tupqueue_issue_v1.patch
Description: Binary data
-- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
