Re: rare crash - FailedAssertion snapbuild.c Line: 580

On 2018-08-29 21:15, Andres Freund wrote:
> Hi,
>
> On 2018-08-29 17:43:17 +0200, Erik Rijkers wrote:
>> To test postgres 11, I still regularly run series of short sessions of
>> pgbench-over-logical-replication (basically the same thing that I used
>> last
>> year [1] - now in a perl incarnation). Most of the time the
>> replication is
>> stable and finishes correctly but sometimes (rarely) I get:
>>
>> TRAP: FailedAssertion("!(TransactionIdPrecedesOrEquals(safeXid,
>> snap->xmin))", File: "snapbuild.c", Line: 580)
>>
>> This will probably be difficult to reproduce and to act upon but I
>> wanted to
>> report it anyway as in the course of the last few months I have seen
>> it
>> several times, on several machines. Always rarely, always postgres 11
>> (I did
>> not try other versions).
>
> Thanks for testing! Could you possibly run the tests with core files
> enabled, so we at get a backtrace in case of trouble? Knowing what the
> values here are would be tremendously helpful...

ok, is this any use?

$ gdb --quiet
/var/data1/pg_stuff/pg_installations/pgsql.REL_11_STABLE/bin/postgres
/var/data1/pg_stuff/tmp/cascade/REL_11_STABLE/6516_gW1Cl/data/core
Reading symbols from
/var/data1/pg_stuff/pg_installations/pgsql.REL_11_STABLE/bin/postgres...done.
[New LWP 147484]
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `postgres: walsender rijkers [local] idle in
transaction '.
Program terminated with signal SIGABRT, Aborted.
#0 0x00007f0fd20e7067 in __GI_raise (sig=sig(at)entry=6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:56
56 ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or
directory.
(gdb) bt
#0 0x00007f0fd20e7067 in __GI_raise (sig=sig(at)entry=6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1 0x00007f0fd20e8448 in __GI_abort () at abort.c:89
#2 0x00000000008880bf in ExceptionalCondition
(conditionName=conditionName(at)entry=0xa417f8
"!(TransactionIdPrecedesOrEquals(safeXid, snap->xmin))",
errorType=errorType(at)entry=0x8d365d "FailedAssertion",
fileName=fileName(at)entry=0xa41223 "snapbuild.c",
lineNumber=lineNumber(at)entry=580) at assert.c:54
#3 0x000000000072676e in SnapBuildInitialSnapshot () at snapbuild.c:580
#4 0x000000000072ed54 in CreateReplicationSlot (cmd=0x223bae0) at
walsender.c:951
#5 exec_replication_command (cmd_string=cmd_string(at)entry=0x21a1cf8
"CREATE_REPLICATION_SLOT \"sub2_6517_6517_18748_sync_18728\" TEMPORARY
LOGICAL pgoutput USE_SNAPSHOT") at walsender.c:1527
#6 0x000000000077e8ee in PostgresMain (argc=<optimized out>,
argv=argv(at)entry=0x21cbbc8, dbname=<optimized out>, username=<optimized
out>) at postgres.c:4155
#7 0x0000000000704fde in BackendRun (port=0x21c4520) at
postmaster.c:4361
#8 BackendStartup (port=0x21c4520) at postmaster.c:4033
#9 ServerLoop () at postmaster.c:1706
#10 0x0000000000705e0f in PostmasterMain (argc=argc(at)entry=12,
argv=argv(at)entry=0x219c470) at postmaster.c:1379
#11 0x0000000000478d80 in main (argc=12, argv=0x219c470) at main.c:228
(gdb)