Skip site navigation (1) Skip section navigation (2)

Re: BUG #3881: lo_open leaks memory

From: Michael Akinde <michael(dot)akinde(at)met(dot)no>
To: pgsql-bugs(at)postgresql(dot)org
Cc: Tomasz Ostrowski <tometzky(at)batory(dot)org(dot)pl>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: BUG #3881: lo_open leaks memory
Date: 2008-01-22 14:45:16
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Thanks for the reply, Tomasz.

We have now done some more performance tests working with pure C/C++ 
code, and the results we are finding seem to indicate that the disk 
thrashing has to do with the OS disk cache, and not as a result of the 
lo_open call. Notably, we have been unable to recreate the problems we 
found with the size of the shared buffers affecting performance, which 
confirms Tom's conclusions.

We still have a performance issue, but the latest round of tests 
indicate a number of places we should try to tweak.

Thanks for your patience, Tom.


Michael Akinde
Database Architect,

Tomasz Ostrowski wrote:
> On Tue, 22 Jan 2008, Michael Akinde wrote:
>>> What I *do* see is that the process size as reported by "top"
>>> quickly jumps to 900MB plus and then sits there.  This is not a
>>> memory leak though, it is just a side effect of the way "top"
>>> reports usage of shared memory.
>> Also, since the blob is opened and closed, why does the process allocate 
>> new memory to open a new blob, rather than reuse existing memory?
> I think a process does not allocate new memory, it just uses his
> shared buffer. The OS does not give physical memory for a process
> immediately when it is allocated for example by malloc, it gives it
> in chunks - only when it is first read or written to.
> Regards
> Tometzky

Attachment: michael.akinde.vcf
Description: text/x-vcard (287 bytes)

In response to

pgsql-bugs by date

Next:From: Alvaro HerreraDate: 2008-01-22 16:18:16
Subject: Re: Gentoo shared_buffers setting (was: BUG #3888:postmaster...)
Previous:From: Tomasz OstrowskiDate: 2008-01-22 14:19:15
Subject: Re: BUG #3881: lo_open leaks memory

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group