Re: [squid-users] Squid 3.4 very high cpu - strace.

From: Alex Crow <>
Date: Fri, 20 Jun 2014 17:21:17 +0100

On 20/06/14 14:28, Eliezer Croitoru wrote:
> OK after reading the config file it seems like there are couple things
> that we\you should be aware of when looking at the issue:
> 1. External helpers code was changed from 3.3 to 3.4 (one way)
> 2. you are using delay_pools.
> 3. you are using ntlm authentication.
> In the past there was suspect which said that the new helpers related
> code might cause an issue like that but yet to be verified.
> (this needs testing and idea on how to show and proof that this is
> either a real suspect or a bogus one)
> About ntlm auth.. There is sure some overhead related to using ntlm
> and cpu usage due to couple layers one on top of the other and it was
> proofed that there is a difference between using ntlm and not using
> ntlm at all.
> It dosn't proof what in ntlm is causing the issue and I am not sure it
> will be fixed due to the basic fact that ntlm maintenance stopped at
> 200X 3 or 6 and which I am not sure about the accurate date yet.
> The only options I see is doing two things:
> Remove the ntlm and group external helpers related acls for a testing
> period to verify that only when these works\runs the high cpu usage is
> there and while the delay_pools are still intact the system runs fine.
> This will narrow down the issues from 3 to 2 "ideal" suspects.
> There is also another suspect which is over-usage of squid ACLs to
> block or allow domains\regex\etc but it can be verified that these are
> not an issue by removing the external_acl and ntlm helpers and test
> how squid behave.
> ** Another tiny detail would be: what bandwidth is this server
> pushing? How many MBps or Mbps(MBps = mbps/8)?
> I know that it can be painful to run these tests but if you have the
> option to verify the issue it will narrow the issue down pretty fast.
> Also I am almost sure that this thread should be summarized into
> either a bug report or first a thread in squid-dev list so you would
> get better help and directions from the developers.
> Thanks,
> Eliezer


The first thing I'm going to try is disabling delay pools for CONNECT,
then after that for all requests.

As disabling NTLM will leave us more open than I'd like that would be
the following step.


Received on Fri Jun 20 2014 - 16:21:20 MDT

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