Re: long running transactions - Mailing list pgsql-performance

From Tobias Brox
Subject Re: long running transactions
Date
Msg-id 20061010174955.GA284@oppetid.no
Whole thread Raw
In response to Re: long running transactions  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: long running transactions
List pgsql-performance
[Tom Lane - Tue at 01:18:27PM -0400]
> >> Hmph.  Is the autovac process actually doing anything (strace would be
> >> revealing)?

It's definitively doing something; mostly reading, but also some few
writes, semops and opens.

> If not, can you attach to the autovac process with gdb and
> >> get a stack trace to see where it's blocked?

(gdb) bt
#0  0xb7c599f8 in select () from /lib/tls/libc.so.6
#1  0x08253c53 in pg_usleep ()
#2  0x0812ee93 in vacuum_delay_point ()
#3  0x0812f2a5 in lazy_vacuum_rel ()
#4  0x0812ef7b in lazy_vacuum_rel ()
#5  0x0812b4b6 in vac_update_relstats ()
#6  0x0812a995 in vacuum ()
#7  0x0818d2ca in autovac_stopped ()
#8  0x0818ceae in autovac_stopped ()
#9  0x0818c848 in autovac_stopped ()
#10 0x0818c4e2 in autovac_start ()
#11 0x08192c11 in PostmasterMain ()
#12 0x08191dcf in PostmasterMain ()
#13 0x081541b1 in main ()

> It'll come back after the autovacuum naptime.  If it gets stuck again,
> please investigate.

It seems stuck, has had the same transid for a long while, and the
number of undeletable dead rows in our tables are increasing.


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