Re: [squid-users] "Reserved number of file descriptors" sudden increase

On 23/10/2012 7:53 p.m., "RODRIGUEZ CEBERIO, Iñigo" wrote:
> Thank you for replying so quickly. I'll upgrade my squid.
>
> However, in this case we have in use 2673 from 4096 and the squid is stuck because of the reserved number of file descriptors rises from 100 to 1400.

Oh right yes, Squid will start limiting inbound accepted connections
when it reaches the reserved limit.

The Reserved FD starts at 100 default value and ONLY increases when
socket() and dup2() operations which create new sockets start to fail.
When that happens it is a strong sign that the OS cannot handle that
many sockets, and Squid limits itself to reserve the unused ones.

I don't see any code to reduce the number - which worries me. Maybe you
hit a fluke occurance of socket() errors and are now stuck with a large
reserved set.

Amos

>
> The normal situation is
> File descriptor usage for squid:
> Maximum number of file descriptors: 4096
> Largest file desc currently in use: 3193
> Number of file desc currently in use: 2673
> Files queued for open: 0
> Available number of file descriptors: 1423
> Reserved number of file descriptors: 100
> Store Disk files open: 1
>
> When the problem starts the only change is
>
> Reserved number of file descriptors: 100 -> 1424
>
> Regards, Inigo.
>
>
> -----Mensaje original-----
> De: Amos Jeffries [mailto:squid3_at_treenet.co.nz]
> Enviado el: martes, 23 de octubre de 2012 5:21
> Para: squid-users_at_squid-cache.org
> Asunto: Re: [squid-users] "Reserved number of file descriptors" sudden increase
>
> On 23/10/2012 3:47 a.m., "RODRIGUEZ CEBERIO, Iñigo" wrote:
>> Hello,
>>
>> I'm running squid 3.0.STABLE13 on a CentOS 5.2.
> Please upgrade, your Squid is no longer suported. Current Squid release is version 3.2.3.
>
>> It works normally and suddenly it colapsed. In the cache.log appears messages telling run out of file descriptors. Using squidclient I can see a change of this parameter, "Reserved number of file descriptors", from 100 to 1424. Here it is the squidclient info about FD:
>>
>> File descriptor usage for squid:
>> Maximum number of file descriptors: 4096
>> Largest file desc currently in use: 3193
>> Number of file desc currently in use: 2673
>> Files queued for open: 0
>> Available number of file descriptors: 1423
>> Reserved number of file descriptors: 1424
>> Store Disk files open: 1
>>
>> Why does that parameter rise from 100 to 1400 in just few seconds? What's going on? Any piece of advise?
> 1400 does not matter. The 2673 is more important - this is number of FD currently open and in use.
>
> It can raise in three situations:
> 1) scanning the disk cache in a "DIRTY" scan to rebuild the index file by file. Requires opening every file on disk and can consume hundreds of FD at once for the one process.
>
> 2) receiving lots of client traffic. Might be a normal peak in traffic, a DoS, or a broken client hammering away repeating a request (usually seen with auth rejecteions).
>
> 3) a forwarding loop, where Squid is processing a request which instructs it to connect to itself as upstream. This is best prevented by configuring "via on".
>
> Amos
Received on Tue Oct 23 2012 - 08:07:10 MDT