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Re: vacuum problem

From: Gaetano Mendola <mendola(at)bigfoot(dot)com>
To: John R Pierce <pierce(at)hogranch(dot)com>
Subject: Re: vacuum problem
Date: 2004-09-11 21:17:50
Message-ID: 41436B7E.7030705@bigfoot.com (view raw or flat)
Thread:
Lists: pgsql-bugs
John R Pierce wrote:

>>> About an hour after mailing that, I realized that the buggy RHEL2.1 
>>> system was running with Intel Hyperthreading enabled (so it appeared 
>>> as 4 CPUs) while the no-problems RH8.0 system had hyperthreading 
>>> enabled (we'd previously been benchmarking some multithreaded stuff 
>>> both ways).   So, its *just* possible that the earlier RHEL2.1 
>>> (kernel 2.4.9-e.43enterprise) had issues which the later RH8 
>>> (2.4.20-28.8smp) were resolved.    I'll not be able to test this 
>>> hypothesis until monday morning.
>>
>>
>> I run RHEL2.1 on the same your HW with HT enabled and I never had a 
>> problem
>> with that.
> 
> 
> are you running PGSql 7.4.x ? (we have this same issue with 7.4.2 and 
> 7.4.5).   fyi, my RHEL2.1 has all available up2date fixes, and I did 
> *NOT* install RH's postgres RPM, rather, I fetched and built 7.4.5 from 
> source

I was running 7.4.2 and since 3 weeks we are running a 7.4.5
Suddenly after the upgrade an ill coded servlets ( in place long time )
started to drive Postgres to PANIC; now the servlet is fixed and the
problem disappeared. See my post: "invalid string enlargement". Tom Lane
also was able to reproduce it and I bet already he fixed the problem.

> could you perhaps give my test program a try?   create a database 
> 'test', a user 'test' with password 'test', and table 'test' as 
> described in my original message, and compile and run this program:
> 
>    http://www.hogranch.com/files/PGTest.java
> 
> compile the java program with Sun J2SE JDK 1.4.x..
> 
>    $ javac PGTest.java

Unfortunatelly I can not try it for two reasons: the machine is a
production machine and I can not use it for experiments and the other
reason is that our Java reference is the 1.3.x  :-(

> (postgresql.jar has to be in your CLASSPATH, or you can specify it as 
> -cp .:/path/postgresql.jar .. I'm using the one that compiled with 7.4.5 
> and my jdk 1.4.x)

Which one ? I hope you are using pg74.213.jdbc3.jar

> I am unable to vacuum the freespace in this table until I stop and 
> restart the postgresql service.    put your autovacuum back online when 
> you're done messing.   I can not reproduce this problem on a RH8 
> (2.4.20.x) system

Do you mean that is not enough stop your java application in order to
retrieve the space with a vacuum ? Do you have some connection in status:
"Idle in transaction" ?




Regards
Gaetano Mendola










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