Re: reindex and copy - deadlock?

Hi Tom,

Here is gdb info.

This happens in our production database
3 times this week. It's totally unacceptable.
I have written a drop/create script to
avoid reindex. However, drop/create
seems to me take more time than reindex
for the whole database.

Your help is greatly appreciated!

Version:
PostgreSQL 7.3.2 on i686-pc-linux-gnu, compiled by GCC
2.96


===========================================
su - postgres
ps -auxww|grep REINDEX
postgres 18903  1.2  8.1 195388 169512 ?     S
04:49   1:54 postgres:postgres db1 [local] REINDEX
postgres 13329  0.0  0.0  1768  620 pts/0    S
07:23   0:00 grep REINDEX
gdb /bin/postgres
GNU gdb Red Hat Linux (5.2-2)
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General
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Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show
warranty" for details.
This GDB was configured as "i386-redhat-linux"...(no
debugging symbols
found)...
(gdb) attach 18903
Attaching to program: /bin/postgres, process 18903
Reading symbols from /usr/lib/libz.so.1...(no
debugging symbols
found)...done.
Loaded symbols for /usr/lib/libz.so.1
Reading symbols from /usr/lib/libreadline.so.4...(no
debugging symbols
found)...done.
Loaded symbols for /usr/lib/libreadline.so.4
Reading symbols from /lib/libtermcap.so.2...(no
debugging symbols
found)...done.
Loaded symbols for /lib/libtermcap.so.2
Reading symbols from /lib/libcrypt.so.1...(no
debugging symbols
found)...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libresolv.so.2...(no
debugging symbols
found)...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/libnsl.so.1...(no debugging
symbols found)...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/libdl.so.2...(no debugging
symbols found)...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/i686/libm.so.6...(no
debugging symbols
found)...done.
Loaded symbols for /lib/i686/libm.so.6
Reading symbols from /lib/i686/libc.so.6...(no
debugging symbols
found)...done.
Loaded symbols for /lib/i686/libc.so.6
Reading symbols from /lib/ld-linux.so.2...(no
debugging symbols
found)...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/libnss_files.so.2...(no
debugging symbols
found)...done.
Loaded symbols for /lib/libnss_files.so.2
0x420e8bb2 in semop () from /lib/i686/libc.so.6
(gdb) bt
#0  0x420e8bb2 in semop () from /lib/i686/libc.so.6
#1  0x080ffa28 in PGSemaphoreLock ()
#2  0x08116432 in LWLockAcquire ()
#3  0x0810f572 in LockBuffer ()
#4  0x0807dea3 in _bt_getbuf ()
#5  0x080813ec in _bt_leafbuild ()
#6  0x080816a6 in _bt_leafbuild ()
#7  0x08081b8b in _bt_leafbuild ()
#8  0x080813cc in _bt_leafbuild ()
#9  0x0807e1d0 in btbuild ()
#10 0x081631c3 in OidFunctionCall3 ()
#11 0x080920a7 in index_build ()
#12 0x08092593 in reindex_index ()
#13 0x08092473 in IndexBuildHeapScan ()
#14 0x0809275d in reindex_relation ()
#15 0x080b9164 in ReindexTable ()
#16 0x08118ece in pg_exec_query_string ()
#17 0x08119fe5 in PostgresMain ()
#18 0x0810214c in ClosePostmasterPorts ()
#19 0x08101a9e in ClosePostmasterPorts ()
#20 0x08100ca1 in PostmasterMain ()
#21 0x08100862 in PostmasterMain ()
#22 0x080deed7 in main ()
#23 0x42017589 in __libc_start_main () from
/lib/i686/libc.so.6
(gdb) quit
The program is running.  Quit anyway (and detach it)?
(y or n) y
Detaching from program: /bin/postgres, process 18903

--- Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Litao Wu <litaowu@yahoo.com> writes:
> > I will use gdb next time. What's this right way to
> > get info as postgres owner?
>
>     $ gdb /path/to/postgres
>     gdb> attach PID-of-backend-process
>     gdb> bt
>     gdb> quit
>
> You might try this for practice on any idle backend;
> it shouldn't affect
> the state of the backend, except for freezing it
> while you issue the
> commands.
>
> If "bt" gives you just a list of numbers and no
> symbolic information,
> then it won't be much help; you'll need to rebuild
> the backend with
> debugging information so that we can make some sense
> of the trace.
>
>             regards, tom lane





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