I found following core file of PG 8.4.0 on my system (Solaris Nevada b119):
fe8ae42d _dowrite (85bf6e8, 3a, 8035e3c, 80350e8) + 8d fe8ae743 _ndoprnt (85bf6e8, 8035ec8, 8035e3c, 0) + 2ba fe8b322d vsnprintf (85bfaf0, 3ff, 85bf6e8, 8035ec8, 0, 0) + 65 082194ea appendStringInfoVA (8035e9c, 85bf6e8, 8035ec8) + 4a 083ca5d3 errmsg (849c340, 0) + 103 0829272d StartAutoVacWorker (fe97f000, 32, 85b82b0, 8035ef4, 82a1496, c) + 3d 082a1901 StartAutovacuumWorker (c, 8035f08, fe8ed28f, 10, 0, 8035fbc) + 71 082a1496 sigusr1_handler (10, 0, 8035fbc) + 186 fe8ed28f __sighndlr (10, 0, 8035fbc, 82a1310) + f fe8e031f call_user_handler (10) + 2af fe8e054f sigacthandler (10, 0, 8035fbc) + df --- called from signal handler with signal 16 (SIGUSR1) --- fe8f37f6 __systemcall (3, fec32b88, 0, fe8e0b46) + 6 fe8e0c71 thr_sigsetmask (3, 85abd50, 0, fe8e0d18) + 139 fe8e0d3f sigprocmask (3, 85abd50, 0) + 31 082a14a4 sigusr1_handler (10, 0, 8036340) + 194 fe8ed28f __sighndlr (10, 0, 8036340, 82a1310) + f fe8e031f call_user_handler (10) + 2af fe8e054f sigacthandler (10, 0, 8036340) + df ... 80x same sighandler stack --- called from signal handler with signal 16 (SIGUSR1) --- fe8f37f6 __systemcall (3, fec32b88, 0, fe8e0b46) + 6 fe8e0c71 thr_sigsetmask (3, 85abd50, 0, fe8e0d18) + 139 fe8e0d3f sigprocmask (3, 85abd50, 0) + 31 082a14a4 sigusr1_handler (10, 0, 80478fc) + 194 fe8ed28f __sighndlr (10, 0, 80478fc, 82a1310) + f fe8e031f call_user_handler (10) + 2af fe8e054f sigacthandler (10, 0, 80478fc) + df --- called from signal handler with signal 16 (SIGUSR1) --- fe8f1867 __pollsys (8047b50, 2, 8047c04, 0) + 7 fe89ce61 pselect (6, 8047c44, 0, 0, 8047c04, 0) + 199 fe89d236 select (6, 8047c44, 0, 0, 8047c38, 0) + 78 0829dc20 ServerLoop (feffb804, bd26003b, 41b21fcb, 85c1de0, 1, 0) + c0 0829d5d0 PostmasterMain (3, 85b72c8) + dd0 08227abf main (3, 85b72c8, 8047df0, 8047d9c) + 22f 080b893d _start (3, 8047e80, 8047ea5, 8047ea8, 0, 8047ec2) + 7d The problem what I see here is that StartAutovacuumWorker() fails and send SIGUSR1 to the postmaster, but it send it too quickly and signal handler is still active. When signal mask is unblocked in sigusr1_handler() than signal handler is run again... The reason why StartAutovacuumWorker() is interesting. Log says: LOG: could not fork autovacuum worker process: Not enough space It is strange and I don't understand it. May be too many nested signal handlers call could cause it. Strange also is that 100ms is not enough to protect this situation, but I think that sleep could interrupted by signal. My suggestion is to set for example gotUSR1=true in sigusr1_handler() and in the server loop check if we got a USR1 signal. It avoids any problems with signal handler which is not currently POSIX compliant anyway. any other ideas? Zdenek -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers