gdb -p 2877
-----------
#0  0x00007f5393dcbbe3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f5396957f51 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffdf412c3f0, cur_timeout=-1, set=0x7f5398d62838) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1048
#2  WaitEventSetWait (set=set@entry=0x7f5398d62838, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffdf412c3f0, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=134217728) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1000
#3  0x00007f53969583d4 in WaitLatchOrSocket (latch=0x7f536ba54d84, wakeEvents=wakeEvents@entry=17, sock=sock@entry=-1, timeout=-1, timeout@entry=0, wait_event_info=wait_event_info@entry=134217728) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:385
#4  0x00007f5396958485 in WaitLatch (latch=<optimized out>, wakeEvents=wakeEvents@entry=17, timeout=timeout@entry=0, wait_event_info=wait_event_info@entry=134217728) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:339
#5  0x00007f53968fc6fb in WaitForBackgroundWorkerShutdown (handle=0x7f5398d092c0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/bgworker.c:1154
#6  0x00007f5396722cbd in WaitForParallelWorkersToExit (pcxt=0x7f5398d08ba8, pcxt=0x7f5398d08ba8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:655
#7  0x00007f53967239d7 in DestroyParallelContext (pcxt=0x7f5398d08ba8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:737
#8  0x00007f539672401d in AtEOXact_Parallel (isCommit=isCommit@entry=0 '\000') at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:1006
#9  0x00007f539672f477 in AbortTransaction () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/xact.c:2538
#10 0x00007f539672fb65 in AbortCurrentTransaction () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/xact.c:3097
#11 0x00007f539697ba5e in PostgresMain (argc=1, argv=argv@entry=0x7f5398d1bbc8, dbname=0x7f5398d1bb98 "coub", username=0x7f5398d1bbb0 "app") at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/tcop/postgres.c:3879
#12 0x00007f53966b41a7 in BackendRun (port=0x7f5398d0c070) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:4405
#13 BackendStartup (port=0x7f5398d0c070) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:4077
#14 ServerLoop () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1755
#15 0x00007f539690ae2d in PostmasterMain (argc=5, argv=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1363
#16 0x00007f53966b558b in main (argc=5, argv=0x7f5398ce95f0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/main/main.c:228


gdb -p 3416
-----------
#0  0x00007f5393dcbbe3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f5396957f51 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffdf412a460, cur_timeout=-1, set=0x7f5398d23378)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1048
#2  WaitEventSetWait (set=0x7f5398d23378, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffdf412a460, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1000
#3  0x00007f539697196b in ConditionVariableSleep (cv=cv@entry=0x7f5396e17178, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/lmgr/condition_variable.c:149
#4  0x00007f5396707057 in _bt_parallel_seize (scan=scan@entry=0x7f5398db1bb0, pageno=pageno@entry=0x7ffdf412a54c)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:811
#5  0x00007f5396707f7a in _bt_readnextpage (scan=scan@entry=0x7f5398db1bb0, blkno=0, dir=dir@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1498
#6  0x00007f5396708de7 in _bt_parallel_readpage (dir=ForwardScanDirection, blkno=<optimized out>, scan=0x7f5398db1bb0)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1631
#7  _bt_first (scan=scan@entry=0x7f5398db1bb0, dir=dir@entry=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:591
#8  0x00007f5396705e99 in btgettuple (scan=0x7f5398db1bb0, dir=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:372
#9  0x00007f53966fff82 in index_getnext_tid (scan=0x7f5398db1bb0, direction=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:541
#10 0x00007f5396700174 in index_getnext (scan=scan@entry=0x7f5398db1bb0, direction=direction@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:679
#11 0x00007f539685795c in IndexNext (node=node@entry=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeIndexscan.c:134
#12 0x00007f5396846fe5 in ExecScanFetch (recheckMtd=0x7f53968577b0 <IndexRecheck>, accessMtd=0x7f53968578f0 <IndexNext>, node=0x7f5398db6c50)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:97
#13 ExecScan (node=0x7f5398db6c50, accessMtd=0x7f53968578f0 <IndexNext>, recheckMtd=0x7f53968577b0 <IndexRecheck>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:164
#14 0x00007f539684cf8c in ExecProcNode (node=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#15 fetch_input_tuple (aggstate=aggstate@entry=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:695
#16 0x00007f539684f26f in agg_retrieve_direct (aggstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2347
#17 ExecAgg (pstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2158
#18 0x00007f5396840e03 in ExecProcNode (node=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#19 ExecutePlan (execute_once=<optimized out>, dest=0x7f5398d87e38, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>,
    planstate=0x7f5398db66f8, estate=0x7f5398db5ce8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:1722
#20 standard_ExecutorRun (queryDesc=0x7f5398db1a90, direction=<optimized out>, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:363
#21 0x00007f538ed03185 in pgss_ExecutorRun (queryDesc=0x7f5398db1a90, direction=ForwardScanDirection, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../contrib/pg_stat_statements/pg_stat_statements.c:889
#22 0x00007f539684572d in ParallelQueryMain (seg=<optimized out>, toc=0x7f5396e17000) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execParallel.c:997
#23 0x00007f53967243c3 in ParallelWorkerMain (main_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:1203
#24 0x00007f53968fc06c in StartBackgroundWorker () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/bgworker.c:835
#25 0x00007f5396908f43 in do_start_bgworker (rw=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5728
#26 maybe_start_bgworkers () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5941
#27 0x00007f5396909bb5 in sigusr1_handler (postgres_signal_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5121
#28 <signal handler called>
#29 0x00007f5393dc4873 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:81
#30 0x00007f53966b3757 in ServerLoop () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1719
#31 0x00007f539690ae2d in PostmasterMain (argc=5, argv=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1363
#32 0x00007f53966b558b in main (argc=5, argv=0x7f5398ce95f0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/main/main.c:228


gdb -p 3417
-----------
#0  0x00007f5393dcbbe3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f5396957f51 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffdf412a460, cur_timeout=-1, set=0x7f5398d23378)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1048
#2  WaitEventSetWait (set=0x7f5398d23378, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffdf412a460, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1000
#3  0x00007f539697196b in ConditionVariableSleep (cv=cv@entry=0x7f5396e17178, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/lmgr/condition_variable.c:149
#4  0x00007f5396707057 in _bt_parallel_seize (scan=scan@entry=0x7f5398db1bb0, pageno=pageno@entry=0x7ffdf412a54c)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:811
#5  0x00007f5396707f7a in _bt_readnextpage (scan=scan@entry=0x7f5398db1bb0, blkno=0, dir=dir@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1498
#6  0x00007f5396708de7 in _bt_parallel_readpage (dir=ForwardScanDirection, blkno=<optimized out>, scan=0x7f5398db1bb0)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1631
#7  _bt_first (scan=scan@entry=0x7f5398db1bb0, dir=dir@entry=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:591
#8  0x00007f5396705e99 in btgettuple (scan=0x7f5398db1bb0, dir=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:372
#9  0x00007f53966fff82 in index_getnext_tid (scan=0x7f5398db1bb0, direction=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:541
#10 0x00007f5396700174 in index_getnext (scan=scan@entry=0x7f5398db1bb0, direction=direction@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:679
#11 0x00007f539685795c in IndexNext (node=node@entry=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeIndexscan.c:134
#12 0x00007f5396846fe5 in ExecScanFetch (recheckMtd=0x7f53968577b0 <IndexRecheck>, accessMtd=0x7f53968578f0 <IndexNext>, node=0x7f5398db6c50)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:97
#13 ExecScan (node=0x7f5398db6c50, accessMtd=0x7f53968578f0 <IndexNext>, recheckMtd=0x7f53968577b0 <IndexRecheck>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:164
#14 0x00007f539684cf8c in ExecProcNode (node=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#15 fetch_input_tuple (aggstate=aggstate@entry=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:695
#16 0x00007f539684f26f in agg_retrieve_direct (aggstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2347
#17 ExecAgg (pstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2158
#18 0x00007f5396840e03 in ExecProcNode (node=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#19 ExecutePlan (execute_once=<optimized out>, dest=0x7f5398d87e38, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>,
    planstate=0x7f5398db66f8, estate=0x7f5398db5ce8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:1722
#20 standard_ExecutorRun (queryDesc=0x7f5398db1a90, direction=<optimized out>, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:363
#21 0x00007f538ed03185 in pgss_ExecutorRun (queryDesc=0x7f5398db1a90, direction=ForwardScanDirection, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../contrib/pg_stat_statements/pg_stat_statements.c:889
#22 0x00007f539684572d in ParallelQueryMain (seg=<optimized out>, toc=0x7f5396e17000) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execParallel.c:997
#23 0x00007f53967243c3 in ParallelWorkerMain (main_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:1203
#24 0x00007f53968fc06c in StartBackgroundWorker () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/bgworker.c:835
#25 0x00007f5396908f43 in do_start_bgworker (rw=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5728
#26 maybe_start_bgworkers () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5941
#27 0x00007f5396909bb5 in sigusr1_handler (postgres_signal_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5121
#28 <signal handler called>
#29 0x00007f5393dc4873 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:81
#30 0x00007f53966b3757 in ServerLoop () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1719
#31 0x00007f539690ae2d in PostmasterMain (argc=5, argv=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1363
#32 0x00007f53966b558b in main (argc=5, argv=0x7f5398ce95f0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/main/main.c:228


gdb -p 3418
-----------
#0  0x00007f5393dcbbe3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f5396957f51 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffdf412a460, cur_timeout=-1, set=0x7f5398d23378)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1048
#2  WaitEventSetWait (set=0x7f5398d23378, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffdf412a460, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1000
#3  0x00007f539697196b in ConditionVariableSleep (cv=cv@entry=0x7f5396e17178, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/lmgr/condition_variable.c:149
#4  0x00007f5396707057 in _bt_parallel_seize (scan=scan@entry=0x7f5398db1bb0, pageno=pageno@entry=0x7ffdf412a54c)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:811
#5  0x00007f5396707f7a in _bt_readnextpage (scan=scan@entry=0x7f5398db1bb0, blkno=0, dir=dir@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1498
#6  0x00007f5396708de7 in _bt_parallel_readpage (dir=ForwardScanDirection, blkno=<optimized out>, scan=0x7f5398db1bb0)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1631
#7  _bt_first (scan=scan@entry=0x7f5398db1bb0, dir=dir@entry=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:591
#8  0x00007f5396705e99 in btgettuple (scan=0x7f5398db1bb0, dir=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:372
#9  0x00007f53966fff82 in index_getnext_tid (scan=0x7f5398db1bb0, direction=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:541
#10 0x00007f5396700174 in index_getnext (scan=scan@entry=0x7f5398db1bb0, direction=direction@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:679
#11 0x00007f539685795c in IndexNext (node=node@entry=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeIndexscan.c:134
#12 0x00007f5396846fe5 in ExecScanFetch (recheckMtd=0x7f53968577b0 <IndexRecheck>, accessMtd=0x7f53968578f0 <IndexNext>, node=0x7f5398db6c50)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:97
#13 ExecScan (node=0x7f5398db6c50, accessMtd=0x7f53968578f0 <IndexNext>, recheckMtd=0x7f53968577b0 <IndexRecheck>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:164
#14 0x00007f539684cf8c in ExecProcNode (node=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#15 fetch_input_tuple (aggstate=aggstate@entry=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:695
#16 0x00007f539684f26f in agg_retrieve_direct (aggstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2347
#17 ExecAgg (pstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2158
#18 0x00007f5396840e03 in ExecProcNode (node=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#19 ExecutePlan (execute_once=<optimized out>, dest=0x7f5398d87e38, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>,
    planstate=0x7f5398db66f8, estate=0x7f5398db5ce8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:1722
#20 standard_ExecutorRun (queryDesc=0x7f5398db1a90, direction=<optimized out>, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:363
#21 0x00007f538ed03185 in pgss_ExecutorRun (queryDesc=0x7f5398db1a90, direction=ForwardScanDirection, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../contrib/pg_stat_statements/pg_stat_statements.c:889
#22 0x00007f539684572d in ParallelQueryMain (seg=<optimized out>, toc=0x7f5396e17000) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execParallel.c:997
#23 0x00007f53967243c3 in ParallelWorkerMain (main_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:1203
#24 0x00007f53968fc06c in StartBackgroundWorker () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/bgworker.c:835
#25 0x00007f5396908f43 in do_start_bgworker (rw=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5728
#26 maybe_start_bgworkers () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5941
#27 0x00007f5396909bb5 in sigusr1_handler (postgres_signal_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5121
#28 <signal handler called>
#29 0x00007f5393dc4873 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:81
#30 0x00007f53966b3757 in ServerLoop () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1719
#31 0x00007f539690ae2d in PostmasterMain (argc=5, argv=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1363
#32 0x00007f53966b558b in main (argc=5, argv=0x7f5398ce95f0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/main/main.c:228


gdb -p 3419
-----------
#0  0x00007f5393dcbbe3 in __epoll_wait_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f5396957f51 in WaitEventSetWaitBlock (nevents=1, occurred_events=0x7ffdf412a460, cur_timeout=-1, set=0x7f5398d23378)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1048
#2  WaitEventSetWait (set=0x7f5398d23378, timeout=timeout@entry=-1, occurred_events=occurred_events@entry=0x7ffdf412a460, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/ipc/latch.c:1000
#3  0x00007f539697196b in ConditionVariableSleep (cv=cv@entry=0x7f5396e17178, wait_event_info=wait_event_info@entry=134217730)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/storage/lmgr/condition_variable.c:149
#4  0x00007f5396707057 in _bt_parallel_seize (scan=scan@entry=0x7f5398db1bb0, pageno=pageno@entry=0x7ffdf412a54c)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:811
#5  0x00007f5396707f7a in _bt_readnextpage (scan=scan@entry=0x7f5398db1bb0, blkno=0, dir=dir@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1498
#6  0x00007f5396708de7 in _bt_parallel_readpage (dir=ForwardScanDirection, blkno=<optimized out>, scan=0x7f5398db1bb0)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:1631
#7  _bt_first (scan=scan@entry=0x7f5398db1bb0, dir=dir@entry=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtsearch.c:591
#8  0x00007f5396705e99 in btgettuple (scan=0x7f5398db1bb0, dir=ForwardScanDirection) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/nbtree/nbtree.c:372
#9  0x00007f53966fff82 in index_getnext_tid (scan=0x7f5398db1bb0, direction=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:541
#10 0x00007f5396700174 in index_getnext (scan=scan@entry=0x7f5398db1bb0, direction=direction@entry=ForwardScanDirection)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/index/indexam.c:679
#11 0x00007f539685795c in IndexNext (node=node@entry=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeIndexscan.c:134
#12 0x00007f5396846fe5 in ExecScanFetch (recheckMtd=0x7f53968577b0 <IndexRecheck>, accessMtd=0x7f53968578f0 <IndexNext>, node=0x7f5398db6c50)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:97
#13 ExecScan (node=0x7f5398db6c50, accessMtd=0x7f53968578f0 <IndexNext>, recheckMtd=0x7f53968577b0 <IndexRecheck>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execScan.c:164
#14 0x00007f539684cf8c in ExecProcNode (node=0x7f5398db6c50) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#15 fetch_input_tuple (aggstate=aggstate@entry=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:695
#16 0x00007f539684f26f in agg_retrieve_direct (aggstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2347
#17 ExecAgg (pstate=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/nodeAgg.c:2158
#18 0x00007f5396840e03 in ExecProcNode (node=0x7f5398db66f8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/include/executor/executor.h:250
#19 ExecutePlan (execute_once=<optimized out>, dest=0x7f5398d87e38, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>,
    planstate=0x7f5398db66f8, estate=0x7f5398db5ce8) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:1722
#20 standard_ExecutorRun (queryDesc=0x7f5398db1a90, direction=<optimized out>, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execMain.c:363
#21 0x00007f538ed03185 in pgss_ExecutorRun (queryDesc=0x7f5398db1a90, direction=ForwardScanDirection, count=0, execute_once=<optimized out>)
    at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../contrib/pg_stat_statements/pg_stat_statements.c:889
#22 0x00007f539684572d in ParallelQueryMain (seg=<optimized out>, toc=0x7f5396e17000) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/executor/execParallel.c:997
#23 0x00007f53967243c3 in ParallelWorkerMain (main_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/access/transam/parallel.c:1203
#24 0x00007f53968fc06c in StartBackgroundWorker () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/bgworker.c:835
#25 0x00007f5396908f43 in do_start_bgworker (rw=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5728
#26 maybe_start_bgworkers () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5941
#27 0x00007f5396909bb5 in sigusr1_handler (postgres_signal_arg=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:5121
#28 <signal handler called>
#29 0x00007f5393dc4873 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:81
#30 0x00007f53966b3757 in ServerLoop () at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1719
#31 0x00007f539690ae2d in PostmasterMain (argc=5, argv=<optimized out>) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/postmaster/postmaster.c:1363
#32 0x00007f53966b558b in main (argc=5, argv=0x7f5398ce95f0) at /build/postgresql-10-U6N320/postgresql-10-10.4/build/../src/backend/main/main.c:228