Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

On Tue, Oct 22, 2019 at 10:52 PM Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>
> I think the patch should do the simplest thing possible, i.e. what it
> does today. Otherwise we'll never get it committed.
>
I found a couple of crashes while reviewing and testing flushing of
open transaction data:
Issue 1:
#0 0x00007f22c5722337 in raise () from /lib64/libc.so.6
#1 0x00007f22c5723a28 in abort () from /lib64/libc.so.6
#2 0x0000000000ec5390 in ExceptionalCondition
(conditionName=0x10ea814 "!dlist_is_empty(head)", errorType=0x10ea804
"FailedAssertion",
fileName=0x10ea7e0 "../../../../src/include/lib/ilist.h",
lineNumber=458) at assert.c:54
#3 0x0000000000b4fb91 in dlist_tail_element_off (head=0x19e4db8,
off=64) at ../../../../src/include/lib/ilist.h:458
#4 0x0000000000b546d0 in ReorderBufferAbortOld (rb=0x191b6b0,
oldestRunningXid=3834) at reorderbuffer.c:1966
#5 0x0000000000b3ca03 in DecodeStandbyOp (ctx=0x19af990,
buf=0x7ffcbc26dc50) at decode.c:332
#6 0x0000000000b3c208 in LogicalDecodingProcessRecord (ctx=0x19af990,
record=0x19afc50) at decode.c:121
#7 0x0000000000b7109e in XLogSendLogical () at walsender.c:2845
#8 0x0000000000b6f5e4 in WalSndLoop (send_data=0xb70f77
<XLogSendLogical>) at walsender.c:2199
#9 0x0000000000b6c7e1 in StartLogicalReplication (cmd=0x1983168) at
walsender.c:1128
#10 0x0000000000b6da6f in exec_replication_command
(cmd_string=0x18f70a0 "START_REPLICATION SLOT \"sub1\" LOGICAL 0/0
(proto_version '1', publication_names '\"pub1\"')")
at walsender.c:1545

Issue 2:
#0 0x00007f1d7ddc4337 in raise () from /lib64/libc.so.6
#1 0x00007f1d7ddc5a28 in abort () from /lib64/libc.so.6
#2 0x0000000000ec4e1d in ExceptionalCondition
(conditionName=0x10ead30 "txn->final_lsn != InvalidXLogRecPtr",
errorType=0x10ea284 "FailedAssertion",
fileName=0x10ea2d0 "reorderbuffer.c", lineNumber=3052) at assert.c:54
#3 0x0000000000b577e0 in ReorderBufferRestoreCleanup (rb=0x2ae36b0,
txn=0x2bafb08) at reorderbuffer.c:3052
#4 0x0000000000b52b1c in ReorderBufferCleanupTXN (rb=0y x2ae36b0,
txn=0x2bafb08) at reorderbuffer.c:1318
#5 0x0000000000b5279d in ReorderBufferCleanupTXN (rb=0x2ae36b0,
txn=0x2b9d778) at reorderbuffer.c:1257
#6 0x0000000000b5475c in ReorderBufferAbortOld (rb=0x2ae36b0,
oldestRunningXid=3835) at reorderbuffer.c:1973
#7 0x0000000000b3ca03 in DecodeStandbyOp (ctx=0x2b676d0,
buf=0x7ffcbc74cc00) at decode.c:332
#8 0x0000000000b3c208 in LogicalDecodingProcessRecord (ctx=0x2b676d0,
record=0x2b67990) at decode.c:121
#9 0x0000000000b70b2b in XLogSendLogical () at walsender.c:2845

These failures come randomly.
I'm not able to reproduce this issue with simple test case.
I have attached the test case which I used to test.
I will further try to find a scenario which could reproduce consistently.
Posting it so that it can help someone in identifying the problem
parallelly through code review by experts.

Regards,
Vignesh
EnterpriseDB: http://www.enterprisedb.com