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Re: CentOS & PostgreSQL help re: TIME_WAIT

From: "Reggie Euser" <reggie(at)busicast(dot)com>
To: <pgsql-admin(at)postgresql(dot)org>
Subject: Re: CentOS & PostgreSQL help re: TIME_WAIT
Date: 2010-01-29 22:20:55
Message-ID: 025701caa131$53c6d710$0301000a@S0030153310 (view raw or flat)
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----- Original Message ----- 
From: "Renato Oliveira" <renato(dot)oliveira(at)grant(dot)co(dot)uk>
To: "Reggie Euser" <reggie(at)busicast(dot)com>; <pgsql-admin(at)postgresql(dot)org>
Sent: Friday, January 29, 2010 10:15 AM
Subject: Re: [ADMIN] CentOS & PostgreSQL help re: TIME_WAIT


Do you have an F5 load balancer in front of these web servers?



Renato Oliveira
Systems Administrator
e-mail: renato(dot)oliveira(at)grant(dot)co(dot)uk

Tel: +44 (0)1763 260811
Fax: +44 (0)1763 262410
http://www.grant.co.uk/

Grant Instruments (Cambridge) Ltd

Company registered in England, registration number 658133

Registered office address:
29 Station Road,
Shepreth,
CAMBS SG8 6GB
UK

-----Original Message-----


From: pgsql-admin-owner(at)postgresql(dot)org 
[mailto:pgsql-admin-owner(at)postgresql(dot)org] On Behalf Of Reggie Euser
Sent: 29 January 2010 15:14
To: pgsql-admin(at)postgresql(dot)org
Subject: Re: [ADMIN] CentOS & PostgreSQL help re: TIME_WAIT

Thanks to both of you. Kevin, it's not a DoS, I'm certain; client problem,
maybe .

Tom - sorry for my confusion. I'm chasing the network/firewall possibilities
as most likely causes.  PostgreSQL is running quite smoothly.

FWIW, what little I know about PostgreSQL, I've picked up by using it,
reading documentation on the web and, most helpfully, reading your comments.
Many thanks again.


----- Original Message -----
From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
>
> Not to discount those possibilities, but I've seen one other cause:
> a storm of connection attempts.  It could be a DoS attack or a
> poorly written client.
>
> -Kevin

>"Reggie Euser" <reggie(at)busicast(dot)com> writes:
>> Zombie PostgreSQL processes in a "TIME_WAIT" state are consuming all
>> available sockets on a web server I'm running. I've Googled & RTFM'ed but
>> am
> >still stumped.  Sure would appreciate any ideas.

That seems a bit confused.  There's no such thing as a "process in a
TIME_WAIT state".  A TCP network socket could be in TIME_WAIT but
it's not a process, and certainly not zombie.  Please be a little
clearer.


In general, sockets sitting a long time in TIME_WAIT would be a network
problem.  That state means the user process already closed the socket
and the network stack is waiting for the other end to acknowledge
connection closure.  If it's not getting the ACK then you have either
buggy network code in one kernel or the other, or a network-level
problem (maybe an overaggressive firewall in between?).

Postgres processes sitting in zombie state would indicate that the
postmaster has somehow gotten wedged and is failing to notice its
dead children.  That shouldn't happen really --- are you still able
to make connections to the database?  It doesn't seem like there'd be
any direct linkage between that and a network problem, but ...

regards, tom lane


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