test=# select * from pg_stat_activity ; -[ RECORD 1 ]----+--------------------------------- datid | 16384 datname | test pid | 16626 usesysid | 10 usename | yugo-n application_name | psql client_addr | client_hostname | client_port | -1 backend_start | 2017-02-07 20:38:28.629562+09 xact_start | 2017-02-07 20:41:21.978381+09 query_start | 2017-02-07 20:41:29.118791+09 state_change | 2017-02-07 20:41:29.118796+09 wait_event_type | wait_event | state | active backend_xid | backend_xmin | query | end; -[ RECORD 2 ]----+--------------------------------- datid | 16384 datname | test pid | 16796 usesysid | 10 usename | yugo-n application_name | postgres_fdw client_addr | client_hostname | client_port | -1 backend_start | 2017-02-07 20:38:49.664541+09 xact_start | 2017-02-07 20:41:25.25321+09 query_start | 2017-02-07 20:41:25.254316+09 state_change | 2017-02-07 20:41:25.254369+09 wait_event_type | wait_event | state | idle in transaction backend_xid | 9088 backend_xmin | 9088 query | DEALLOCATE pgsql_fdw_prep_4 -[ RECORD 3 ]----+--------------------------------- datid | 16384 datname | test pid | 16840 usesysid | 10 usename | yugo-n application_name | postgres_fdw client_addr | client_hostname | client_port | -1 backend_start | 2017-02-07 20:38:54.579606+09 xact_start | 2017-02-07 20:41:27.815021+09 query_start | 2017-02-07 20:41:29.118962+09 state_change | 2017-02-07 20:41:29.118966+09 wait_event_type | Lock wait_event | transactionid state | active backend_xid | 9089 backend_xmin | 9088 query | COMMIT TRANSACTION $ sudo gdb -p 16626 ... (gdb) bt #0 0x00007f4116434fc0 in __poll_nocancel () at ../sysdeps/unix/syscall-template.S:81 #1 0x00007f410c3b82a6 in poll (__timeout=, __nfds=1, __fds=0x7ffcb6936100) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46 #2 pqSocketPoll (end_time=-1, forWrite=0, forRead=1, sock=) at fe-misc.c:1134 #3 pqSocketCheck (conn=conn@entry=0x2481850, forRead=forRead@entry=1, forWrite=forWrite@entry=0, end_time=end_time@entry=-1) at fe-misc.c:1076 #4 0x00007f410c3b8b90 in pqWaitTimed (forRead=forRead@entry=1, forWrite=forWrite@entry=0, conn=conn@entry=0x2481850, finish_time=finish_time@entry=-1) at fe-misc.c:1008 #5 0x00007f410c3b8bdc in pqWait (forRead=forRead@entry=1, forWrite=forWrite@entry=0, conn=conn@entry=0x2481850) at fe-misc.c:991 #6 0x00007f410c3b6e39 in PQgetResult (conn=conn@entry=0x2481850) at fe-exec.c:1732 #7 0x00007f410c3b712e in PQexecFinish (conn=conn@entry=0x2481850) at fe-exec.c:2018 #8 0x00007f410c3b71f2 in PQexec (conn=conn@entry=0x2481850, query=query@entry=0x7f410c5e1041 "COMMIT TRANSACTION") at fe-exec.c:1852 #9 0x00007f410c5ded9f in do_sql_command (conn=0x2481850, sql=sql@entry=0x7f410c5e1041 "COMMIT TRANSACTION") at connection.c:355 #10 0x00007f410c5df900 in pgfdw_xact_callback (event=XACT_EVENT_PRE_COMMIT, arg=) at connection.c:624 #11 0x00000000004d33bd in CallXactCallbacks (event=XACT_EVENT_PRE_COMMIT) at xact.c:3336 #12 CommitTransaction () at xact.c:1980 #13 0x00000000004d42a5 in CommitTransactionCommand () at xact.c:2881 #14 0x00000000006b9925 in finish_xact_command () at postgres.c:2457 #15 0x00000000006bd262 in finish_xact_command () at postgres.c:2448 #16 exec_simple_query (query_string=0x2440ea0 "end;") at postgres.c:1111 #17 PostgresMain (argc=, argv=argv@entry=0x23ed370, dbname=0x23ed258 "test", username=) at postgres.c:4076 #18 0x000000000046b5fe in BackendRun (port=0x23eaf00) at postmaster.c:4271 #19 BackendStartup (port=0x23eaf00) at postmaster.c:3945 #20 ServerLoop () at postmaster.c:1701 #21 0x0000000000663246 in PostmasterMain (argc=argc@entry=1, argv=argv@entry=0x23c3140) at postmaster.c:1309 #22 0x000000000046c0fe in main (argc=1, argv=0x23c3140) at main.c:228 $ sudo gdb -p 16840 ... (gdb) bt #0 0x00007f41164429f3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81 #1 0x000000000069d926 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffcb6935830, cur_timeout=-1, set=0x2494d40) at latch.c:990 #2 WaitEventSetWait (set=set@entry=0x2494d40, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffcb6935830, nevents=nevents@entry=1) at latch.c:944 #3 0x000000000069dd46 in WaitLatchOrSocket (latch=0x7f411532465c, wakeEvents=wakeEvents@entry=1, sock=sock@entry=-1, timeout=-1, timeout@entry=0) at latch.c:347 #4 0x000000000069dddd in WaitLatch (latch=, wakeEvents=wakeEvents@entry=1, timeout=timeout@entry=0) at latch.c:302 #5 0x00000000006ac33b in ProcSleep (locallock=locallock@entry=0x23e9030, lockMethodTable=lockMethodTable@entry=0x8f9960 ) at proc.c:1221 #6 0x00000000006a7438 in WaitOnLock (locallock=locallock@entry=0x23e9030, owner=owner@entry=0x23eeef8) at lock.c:1703 #7 0x00000000006a8a05 in LockAcquireExtended (locktag=locktag@entry=0x7ffcb6935b60, lockmode=lockmode@entry=5, sessionLock=sessionLock@entry=0 '\000', dontWait=dontWait@entry=0 '\000', reportMemoryError=reportMemoryError@entry=1 '\001') at lock.c:998 #8 0x00000000006a8d71 in LockAcquire (locktag=locktag@entry=0x7ffcb6935b60, lockmode=lockmode@entry=5, sessionLock=sessionLock@entry=0 '\000', dontWait=dontWait@entry=0 '\000') at lock.c:688 #9 0x00000000006a6aae in XactLockTableWait (xid=xid@entry=9088, rel=rel@entry=0x7f4116fdff18, ctid=ctid@entry=0x2494c70, oper=oper@entry=XLTW_InsertIndex) at lmgr.c:587 #10 0x00000000004ad585 in _bt_doinsert (rel=rel@entry=0x7f4116fdff18, itup=itup@entry=0x2494c70, checkUnique=checkUnique@entry=UNIQUE_CHECK_EXISTING, heapRel=heapRel@entry=0x7f4116fdc010) at nbtinsert.c:183 #11 0x00000000004afc81 in btinsert (rel=0x7f4116fdff18, values=, isnull=, ht_ctid=0x7ffcb69363c4, heapRel=0x7f4116fdc010, checkUnique=UNIQUE_CHECK_EXISTING) at nbtree.c:284 #12 0x000000000055ab2b in unique_key_recheck (fcinfo=) at constraint.c:167 #13 0x000000000059a337 in ExecCallTriggerFunc (trigdata=trigdata@entry=0x7ffcb6936400, tgindx=tgindx@entry=0, finfo=finfo@entry=0x2490db0, instr=instr@entry=0x0, per_tuple_context=per_tuple_context@entry=0x23f8048) at trigger.c:1909 #14 0x000000000059b8a3 in AfterTriggerExecute (trigdesc=0x2490ca0, trigdesc=0x2490ca0, trig_tuple_slot2=0x0, trig_tuple_slot1=0x0, per_tuple_context=0x23f8048, instr=0x0, finfo=0x2490db0, rel=0x7f4116fdc010, event=0x2492ec0) at trigger.c:3640 #15 afterTriggerInvokeEvents (events=events@entry=0xc027f0 , firing_id=1, estate=0x2490a80, estate@entry=0x0, delete_ok=delete_ok@entry=1 '\001') at trigger.c:3831 #16 0x000000000059fc80 in AfterTriggerFireDeferred () at trigger.c:4063 #17 0x00000000004d3385 in CommitTransaction () at xact.c:1969 #18 0x00000000004d42a5 in CommitTransactionCommand () at xact.c:2881 #19 0x00000000006b9925 in finish_xact_command () at postgres.c:2457 #20 0x00000000006bd262 in finish_xact_command () at postgres.c:2448 #21 exec_simple_query (query_string=0x2442f20 "COMMIT TRANSACTION") at postgres.c:1111 #22 PostgresMain (argc=, argv=argv@entry=0x23ed378, dbname=0x23ed258 "test", username=) at postgres.c:4076 #23 0x000000000046b5fe in BackendRun (port=0x23eaf00) at postmaster.c:4271 #24 BackendStartup (port=0x23eaf00) at postmaster.c:3945 #25 ServerLoop () at postmaster.c:1701 #26 0x0000000000663246 in PostmasterMain (argc=argc@entry=1, argv=argv@entry=0x23c3140) at postmaster.c:1309 #27 0x000000000046c0fe in main (argc=1, argv=0x23c3140) at main.c:228