From: Jerry Sievers <gsievers19@comcast.net>
To: pgsql-admin@postgresql.org
Subject: Escaping a blocked sendto() syscall without causing a restart
Date: Thu, 17 Jan 2013 14:36:24 -0600
Message-ID: <87obgnczsn.fsf@comcast.net> (raw)
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-admin>
Does anyone know if one of the signals below can be sent to break out
,of this state *without* the postmaster sensing a crashed backend?
I've seen several times in the past at other companies, backends that
will not respond to cancel nor SIGTERM due to syscall that's blocked
on IO.
Quite often though apparently the backend would notice the broken
socket eventually and receive the signals and exit cleanly.
I've got one that's been wedged like that for a couple days now.
I recall trying several in a similar situation a while ago and of
course one of them interrupted the syscall all right but it was an
abort and we got the customary spontaneous postmaster restart.
PostgreSQL 8.4.13 on x86_64-pc-linux-gnu, compiled by GCC gcc-4.3.real (Debian 4.3.2-1.1) 4.3.2, 64-bit
$ uname -a
Linux somebox.foo.zizzy 2.6.36 #5 SMP Thu Jul 28 17:52:31 UTC 2011 x86_64 GNU/Linux
$
$ strace -p 31603
Process 31603 attached - interrupt to quit
sendto(9, "default_rate_3m_v4: 0.1224\nmonth_"..., 3440, 0, NULL, 0
<unfinished ...>
Process 31603 detached
$ $
$ kill -l
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL
5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE
9) SIGKILL 10) SIGUSR1 11) SIGSEGV 12) SIGUSR2
13) SIGPIPE 14) SIGALRM 15) SIGTERM 16) SIGSTKFLT
17) SIGCHLD 18) SIGCONT 19) SIGSTOP 20) SIGTSTP
21) SIGTTIN 22) SIGTTOU 23) SIGURG 24) SIGXCPU
25) SIGXFSZ 26) SIGVTALRM 27) SIGPROF 28) SIGWINCH
29) SIGIO 30) SIGPWR 31) SIGSYS 34) SIGRTMIN
35) SIGRTMIN+1 36) SIGRTMIN+2 37) SIGRTMIN+3 38) SIGRTMIN+4
39) SIGRTMIN+5 40) SIGRTMIN+6 41) SIGRTMIN+7 42) SIGRTMIN+8
43) SIGRTMIN+9 44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12
47) SIGRTMIN+13 48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14
51) SIGRTMAX-13 52) SIGRTMAX-12 53) SIGRTMAX-11 54) SIGRTMAX-10
55) SIGRTMAX-9 56) SIGRTMAX-8 57) SIGRTMAX-7 58) SIGRTMAX-6
59) SIGRTMAX-5 60) SIGRTMAX-4 61) SIGRTMAX-3 62) SIGRTMAX-2
63) SIGRTMAX-1 64) SIGRTMAX
$
Thanks
--
Jerry Sievers
e: jerry.sievers@comcast.net
p: 312.241.7800
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To: pgsql-admin@postgresql.org
Cc: gsievers19@comcast.net
Subject: Re: Escaping a blocked sendto() syscall without causing a restart
In-Reply-To: <87obgnczsn.fsf@comcast.net>
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