On 18/10/11 18:02, Justin Lawler wrote:
Hi,
Just a follow up to this. Anyone know how/when squid will trigger
ICAP service as down?
When it stops responding.
From ICAP logs, we can see squid is sending in an 'OPTIONS' request
every second. Is this request a health-check on the ICAP service? Or
is there any other function to it?
Yes, and yes. A service responding to OPTIONS is obviously running.
See the ICAP specification for what else its used for:
http://www.rfc-editor.org/rfc/rfc3507.txt section 4.10
We're still seeing very long pauses in our ICAP server that should
really trigger an ICAP error on squid, but it isn't always.
Thanks, Justin
Can you run it against a better GC? I've heard that there were competing
GC algorithms in Java these last few years with various behaviour benefits.
-----Original Message-----
> From: Justin Lawler
Hi,
We have an application that integrates with squid over ICAP - a java
based application. We're finding that the java application has very
long garbage collection pauses at times (20+ seconds), where the
application becomes completely unresponsive.
We have squid configured to use this application as an essential
service, with a timeout for 20 seconds. If the application goes into
a GC pause, squid can throw an 'essential ICAP service is down'
error.
The problem is most of the time it doesn't. It only happens maybe 20%
of the time - even though some of the pauses are 25 seconds+.
Squid is setup to do an 'OPTIONS' request on the java application
every second, so I don't understand why it doesn't detect the java
application becoming unresponsive.
It's very likely these requests are being made and being serviced, just
very much later.
http://www.squid-cache.org/Doc/config/icap_connect_timeout/
Note the default is: 30-60 seconds inherited from [peer_]connect_timeout.
Also http://www.squid-cache.org/Doc/config/icap_service_failure_limit/
So 10 failures in a row are required to detect an outage. Each failure
takes 30+ seconds to be noticed.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE9 or 3.1.16
Beta testers wanted for 3.2.0.13
