[sqlsmith] Failed assertion in BecomeLockGroupLeader

Hi,

tonight's sqlsmith run yielded another core dump:

TRAP: FailedAssertion("!(MyProc->lockGroupLeader == ((void *)0))", File: "proc.c", Line: 1787)

I couldn't identifiy a query for it though: debug_query_string is empty.
Additionally, the offending query was not reported in the error context
as it typically is for non-parallel executor crashes.

regards,
Andreas

GNU gdb (Debian 7.7.1+dfsg-5) 7.7.1
Core was generated by `postgres: bgworker: parallel worker for PID 4706 '.
Program terminated with signal SIGABRT, Aborted.
#0 0x00007ff1bda16067 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: Datei oder Verzeichnis nicht gefunden.
#0 0x00007ff1bda16067 in __GI_raise (sig=sig(at)entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1 0x00007ff1bda17448 in __GI_abort () at abort.c:89
#2 0x00000000007eaa11 in ExceptionalCondition (conditionName=conditionName(at)entry=0x988318 "!(MyProc->lockGroupLeader == ((void *)0))", errorType=errorType(at)entry=0x82a45d "FailedAssertion", fileName=fileName(at)entry=0x8760e5 "proc.c", lineNumber=lineNumber(at)entry=1787) at assert.c:54
#3 0x00000000006e3e7b in BecomeLockGroupLeader () at proc.c:1787
#4 0x00000000004e6a59 in LaunchParallelWorkers (pcxt=pcxt(at)entry=0x1db05c8) at parallel.c:437
#5 0x00000000005ef2d7 in ExecGather (node=node(at)entry=0x1d9d0b8) at nodeGather.c:168
#6 0x00000000005dd788 in ExecProcNode (node=node(at)entry=0x1d9d0b8) at execProcnode.c:515
#7 0x00000000005d999f in ExecutePlan (dest=0x1d7d310, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>, planstate=0x1d9d0b8, estate=0x1d9c858) at execMain.c:1567
#8 standard_ExecutorRun (queryDesc=0x1db0080, direction=<optimized out>, count=0) at execMain.c:338
#9 0x00000000005dcb3f in ParallelQueryMain (seg=<optimized out>, toc=0x7ff1be507000) at execParallel.c:716
#10 0x00000000004e608b in ParallelWorkerMain (main_arg=<optimized out>) at parallel.c:1033
#11 0x0000000000683a42 in StartBackgroundWorker () at bgworker.c:726
#12 0x000000000068eb82 in do_start_bgworker (rw=0x1d24ec0) at postmaster.c:5531
#13 maybe_start_bgworker () at postmaster.c:5706
#14 0x000000000046c993 in ServerLoop () at postmaster.c:1762
#15 0x00000000006909fe in PostmasterMain (argc=argc(at)entry=3, argv=argv(at)entry=0x1cfa560) at postmaster.c:1298
#16 0x000000000046d5ed in main (argc=3, argv=0x1cfa560) at main.c:228
(gdb) bt full
#3 0x00000000006e3e7b in BecomeLockGroupLeader () at proc.c:1787
leader_lwlock = <optimized out>
#4 0x00000000004e6a59 in LaunchParallelWorkers (pcxt=pcxt(at)entry=0x1db05c8) at parallel.c:437
oldcontext = 0x1d9ced0
worker = {
bgw_name = "\220\a\333\001\000\000\000\000\370\340L\276\361\177\000\000\370\373\025\264\361\177\000\000P\a\333\001\000\000\000\000X\310\331\001\000\000\000\000\004\000\000\000\000\000\000\000\310\005\333\001\000\000\000\000\233\222J\000\000\000\000",
bgw_flags = 1,
bgw_start_time = BgWorkerStart_PostmasterStart,
bgw_restart_time = 1,
bgw_main = 0x0,
bgw_library_name = "\000\000\000\000\000\000\000\000\001\000\000\000\000\000\000\000u\222J\000\000\000\000\000\350\336\331\001\000\000\000\000\360\260a\000\000\000\000\000\200\315]\000\000\000\000\000\300\330\367\217\375\177\000\000h\205\333\001\000\000\000",
bgw_function_name = "`\346\327\001\000\000\000\000\004\000\000\000\000\000\000\000\360\260a\000\000\000\000\000\200\315]\000\000\000\000\000\300\330\367\217\375\177\000\000h\317\331\001\000\000\000\000\210\325\327\001\000\000\000\000\004\000\000\000\000\000\000",
bgw_main_arg = 6402288,
bgw_extra = "X\310\331\001\000\000\000\000\000\000\000\000\000\000\000\000\060\233\333\001\000\000\000\000\001\000\000\000\000\000\000\000\004\000\000\000\000\000\000\000l\321]\000\000\000\000\000\000\000\000\000\000\000\000\000H-\334\001\000\000\000\000h\317\331\001\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\274\341M\276\361\177\000\000\310\005\333\001\000\000\000\000\004\000\000\000\000\000\000\000\310\005\333\001\000\000\000\000\000\000\000\000\000\000\000",
bgw_notify_pid = 4
}
i = <optimized out>
any_registrations_failed = 0 '\000'
#5 0x00000000005ef2d7 in ExecGather (node=node(at)entry=0x1d9d0b8) at nodeGather.c:168
pcxt = 0x1db05c8
estate = <optimized out>
gather = 0x1d7d440
fslot = 0x1d9ced0
i = <optimized out>
resultSlot = <optimized out>
isDone = ExprSingleResult
econtext = <optimized out>
#6 0x00000000005dd788 in ExecProcNode (node=node(at)entry=0x1d9d0b8) at execProcnode.c:515
result = <optimized out>
__func__ = "ExecProcNode"
#7 0x00000000005d999f in ExecutePlan (dest=0x1d7d310, direction=<optimized out>, numberTuples=0, sendTuples=<optimized out>, operation=CMD_SELECT, use_parallel_mode=<optimized out>, planstate=0x1d9d0b8, estate=0x1d9c858) at execMain.c:1567
slot = <optimized out>
current_tuple_count = 0
#8 standard_ExecutorRun (queryDesc=0x1db0080, direction=<optimized out>, count=0) at execMain.c:338
estate = 0x1d9c858
operation = CMD_SELECT
dest = 0x1d7d310
sendTuples = <optimized out>
#9 0x00000000005dcb3f in ParallelQueryMain (seg=<optimized out>, toc=0x7ff1be507000) at execParallel.c:716
buffer_usage = <optimized out>
instrumentation = 0x0
instrument_options = 0
#10 0x00000000004e608b in ParallelWorkerMain (main_arg=<optimized out>) at parallel.c:1033
seg = 0x1d29d30
toc = 0x7ff1be507000
fps = 0x7ff1be51ec38
error_queue_space = <optimized out>
mq = <optimized out>
mqh = <optimized out>
libraryspace = <optimized out>
gucspace = <optimized out>
combocidspace = <optimized out>
tsnapspace = <optimized out>
asnapspace = <optimized out>
tstatespace = <optimized out>
msgbuf = {
data = 0x0,
len = 8,
maxlen = 1024,
cursor = 75
}
__func__ = "ParallelWorkerMain"
#11 0x0000000000683a42 in StartBackgroundWorker () at bgworker.c:726
local_sigjmp_buf = {{
__jmpbuf = {30559936, 3179006107653964804, 140727018841376, 1461888082, 4294967295, 30560912, -3178127926870473724, 3179007261678568452},
__mask_was_saved = 1,
__saved_mask = {
__val = {18446744066192964103, 0, 0, 140727018839040, 0, 2415385408, 30532816, 140727018782720, 0, 0, 140727018840336, 18446744073709551615, 0, 30514160, 140676256394695, 8589934591}
}
}}
buf = "bgworker: parallel worker for PID 4706\000\000\345[...]"
worker = 0x1d24ec0
entrypt = <optimized out>
__func__ = "StartBackgroundWorker"
#12 0x000000000068eb82 in do_start_bgworker (rw=0x1d24ec0) at postmaster.c:5531
worker_pid = <optimized out>
#13 maybe_start_bgworker () at postmaster.c:5706
rw = 0x1d24ec0
iter = {
cur = 0x1d25048,
next = 0x0,
prev = 0x1d207d8
}
now = <optimized out>
#14 0x000000000046c993 in ServerLoop () at postmaster.c:1762
rmask = {
fds_bits = {24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
}
selres = <optimized out>
now = <optimized out>
readmask = {
fds_bits = {24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
}
last_lockfile_recheck_time = 1461888082
last_touch_time = 1461885050
__func__ = "ServerLoop"
#15 0x00000000006909fe in PostmasterMain (argc=argc(at)entry=3, argv=argv(at)entry=0x1cfa560) at postmaster.c:1298
opt = <optimized out>
status = <optimized out>
userDoption = <optimized out>
listen_addr_saved = <optimized out>
i = <optimized out>
output_config_variable = <optimized out>
__func__ = "PostmasterMain"
#16 0x000000000046d5ed in main (argc=3, argv=0x1cfa560) at main.c:228