Segmentation Fault in logical decoding get/peek API

Hi everyone,

PostgreSQL backend crashing with segmentation fault 11, while consuming big
transaction changes using pg_logical_slot_(peek|get)_changes. We are using
postgresql version 9.5.10.

About the big transaction : pg_xlog_dump shows 161426 records, and it spread
across 3 WAL files.

BackTace of the backend :

Program received signal SIGSEGV, Segmentation fault.
ReorderBufferCommit (rb=0xd17dc8, xid=<value optimized out>,
commit_lsn=7224098593984, end_lsn=<value optimized out>, commit_time=<value
optimized out>, origin_id=<value optimized out>, origin_lsn=0) at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/reorderbuffer.c:1380
1380 change->action = REORDER_BUFFER_CHANGE_INSERT;

#0 ReorderBufferCommit (rb=0xd17dc8, xid=<value optimized out>,
commit_lsn=7224098593984, end_lsn=<value optimized out>, commit_time=<value
optimized out>, origin_id=<value optimized out>, origin_lsn=0) at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/reorderbuffer.c:1380
#1 0x0000000000675cd1 in DecodeCommit (ctx=0xcffdb8, record=<value
optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/decode.c:549
#2 DecodeXactOp (ctx=0xcffdb8, record=<value optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/decode.c:234
#3 LogicalDecodingProcessRecord (ctx=0xcffdb8, record=<value optimized
out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/decode.c:111
#4 0x00000000006772e5 in pg_logical_slot_get_changes_guts
(fcinfo=0x7ffea1ef0b90, confirm=0 '\000', binary=0 '\000') at
/home/test/compile/../postgresql-9.5.10/src/backend/replication/logical/logicalfuncs.c:442
#5 0x00000000005c4074 in ExecMakeTableFunctionResult (funcexpr=0xce55a0,
econtext=0xce5190, argContext=<value optimized out>, expectedDesc=0xce6360,
randomAccess=0 '\000') at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execQual.c:2189
#6 0x00000000005d8652 in FunctionNext (node=0xce5080) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/nodeFunctionscan.c:95
#7 0x00000000005c4d73 in ExecScanFetch (node=0xce5080, accessMtd=0x5d83a0
<FunctionNext>, recheckMtd=0x5d7cd0 <FunctionRecheck>) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execScan.c:95
#8 ExecScan (node=0xce5080, accessMtd=0x5d83a0 <FunctionNext>,
recheckMtd=0x5d7cd0 <FunctionRecheck>) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execScan.c:145
#9 0x00000000005bd808 in ExecProcNode (node=0xce5080) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execProcnode.c:442
#10 0x00000000005caca6 in fetch_input_tuple (aggstate=0xce4808) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/nodeAgg.c:487
#11 0x00000000005cc286 in agg_retrieve_direct (node=<value optimized out>)
at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/nodeAgg.c:1683
#12 ExecAgg (node=<value optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/nodeAgg.c:1508
#13 0x00000000005bd748 in ExecProcNode (node=0xce4808) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execProcnode.c:496
#14 0x00000000005bbfdf in ExecutePlan (queryDesc=0xce93a8, direction=<value
optimized out>, count=0) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execMain.c:1549
#15 standard_ExecutorRun (queryDesc=0xce93a8, direction=<value optimized
out>, count=0) at
/home/test/compile/../postgresql-9.5.10/src/backend/executor/execMain.c:337
#16 0x00000000006c1f57 in PortalRunSelect (portal=0xd2b9c8, forward=<value
optimized out>, count=0, dest=<value optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/tcop/pquery.c:942
#17 0x00000000006c31c7 in PortalRun (portal=0xd2b9c8,
count=9223372036854775807, isTopLevel=1 '\001', dest=0xced478,
altdest=0xced478, completionTag=0x7ffea1ef1440 "") at
/home/test/compile/../postgresql-9.5.10/src/backend/tcop/pquery.c:786
#18 0x00000000006bff50 in exec_simple_query (query_string=0xccd7e8 "select
count(*) from pg_logical_slot_peek_changes('pg_slotnew',null,1000);") at
/home/test/compile/../postgresql-9.5.10/src/backend/tcop/postgres.c:1096
#19 0x00000000006c157c in PostgresMain (argc=<value optimized out>,
argv=<value optimized out>, dbname=0xc36100 "sasdb", username=<value
optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/tcop/postgres.c:4049
#20 0x0000000000665d1c in BackendRun (argc=<value optimized out>,
argv=<value optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/postmaster/postmaster.c:4264
#21 BackendStartup (argc=<value optimized out>, argv=<value optimized out>)
at
/home/test/compile/../postgresql-9.5.10/src/backend/postmaster/postmaster.c:3938
#22 ServerLoop (argc=<value optimized out>, argv=<value optimized out>) at
/home/test/compile/../postgresql-9.5.10/src/backend/postmaster/postmaster.c:1703
#23 PostmasterMain (argc=<value optimized out>, argv=<value optimized out>)
at
/home/test/compile/../postgresql-9.5.10/src/backend/postmaster/postmaster.c:1311
#24 0x00000000005f4309 in main (argc=3, argv=0xc34b60) at
/home/test/compile/../postgresql-9.5.10/src/backend/main/main.c:228

Is it a bug? Is any way i could avoid this?
If you guys need any information for debugging, kindly let me know.

Thanks in advance,

Sudalai

-----
sudalai
--
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