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Posted to users@tomcat.apache.org by Stephen Booth <s....@ed.ac.uk> on 2015/11/03 22:01:43 UTC
Making fail-over work with PermGen errors
Does anyone have any advice about how to make fail-over work more
cleanly with PermGen errors (other than the obvious one of not letting
PermGen errors occur)
I'm using apache ModProxy to connect to tomcat over ajp with additional
hot-spare servers confgured for fail-over but if I mess up and let the
jvm run out of PermGen space then tomcat seems to stay alive enough to
prevent fail-over but not enough to actually serve any content.
Stephen
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The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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Re: Making fail-over work with PermGen errors
Posted by Stephen Booth <s....@ed.ac.uk>.
On 04/11/2015 19:59, Christopher Schultz wrote:
> Memory-related errors are always problematic.
>
> Do you have any instrumentation/monitoring to check the liveness of your
> Tomcat nodes? Can it detect the OOME condition? If so, you should be
> able to notify the load-balancer that something had gone wrong. I'm
> unsure of how to do it with mod_proxy_ajp, but mod_jk can be
> re-configured externally e.g. by calling curl with a specially-crafted
> URL[1].
Yes I think thats the route we are going to go down. Actually
re-analysing the problem I think the load balancer might have
successfully failed over but because the dead node was not noticed it
hung around in a blocked state until the node was needed.
Stephen
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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Re: Making fail-over work with PermGen errors
Posted by Christopher Schultz <ch...@christopherschultz.net>.
Stephen,
On 11/3/15 4:01 PM, Stephen Booth wrote:
> Does anyone have any advice about how to make fail-over work more
> cleanly with PermGen errors (other than the obvious one of not letting
> PermGen errors occur)
>
> I'm using apache ModProxy to connect to tomcat over ajp with additional
> hot-spare servers confgured for fail-over but if I mess up and let the
> jvm run out of PermGen space then tomcat seems to stay alive enough to
> prevent fail-over but not enough to actually serve any content.
Memory-related errors are always problematic.
Do you have any instrumentation/monitoring to check the liveness of your
Tomcat nodes? Can it detect the OOME condition? If so, you should be
able to notify the load-balancer that something had gone wrong. I'm
unsure of how to do it with mod_proxy_ajp, but mod_jk can be
re-configured externally e.g. by calling curl with a specially-crafted
URL[1].
-chris
[1] https://wiki.apache.org/tomcat/tools/mod_jk.py
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