LHC@home

Hi all,

This message is only relevant if you run your own squid proxy server for ATLAS tasks.

After the CERN database outage last week, a problem was seen with the cached information on squid proxy servers all over the ATLAS Grid which can cause tasks to fail. The solution to the problem is to restart the squid service, so if you are running your own squid please restart it in order to avoid potential problems.

The ATLAS-managed squid servers which tasks use by default were restarted earlier today, so if you saw strange failures in tasks between Thursday last week and now this might have been the reason.

Hi all,

This message is only relevant if you run your own squid proxy server for ATLAS tasks.

After the CERN database outage last week, a problem was seen with the cached information on squid proxy servers all over the ATLAS Grid which can cause tasks to fail. The solution to the problem is to restart the squid service, so if you are running your own squid please restart it in order to avoid potential problems.

The ATLAS-managed squid servers which tasks use by default were restarted earlier today, so if you saw strange failures in tasks between Thursday last week and now this might have been the reason.

By restart do you just mean squid -k restart
or deleting the cache and starting fresh?

So today's power outage was not entirely unnecessary. Have not cleared cache.

restart the squid service

It sounds like restart daemon is enough.

This is also in regards to your post in the Theory thread:
https://lhcathome.cern.ch/lhcathome/forum_thread.php?id=5431&postid=42775


You may first check your access.log and cache.log.
Do you notice error messages that correspond to your issues?

If no, squid is most likely running fine and the issues are caused by something else.

If yes, you should clear the cache and restart fresh.

You may also insert the following line in your squid.conf and do a "squid -k reconfigure".

shutdown_lifetime 3 seconds

This avoids the 60 seconds default delay when you shutdown/restart squid but I'm not 100% sure if changing this timeout requires a squid -k restart. At least Squid will be prepared for the next restart.

This is also in regards to your post in the Theory thread:
https://lhcathome.cern.ch/lhcathome/forum_thread.php?id=5431&postid=42775


You may first check your access.log and cache.log.
Do you notice error messages that correspond to your issues?

If no, squid is most likely running fine and the issues are caused by something else.

If yes, you should clear the cache and restart fresh.

You may also insert the following line in your squid.conf and do a "squid -k reconfigure".

shutdown_lifetime 3 seconds

This avoids the 60 seconds default delay when you shutdown/restart squid but I'm not 100% sure if changing this timeout requires a squid -k restart. At least Squid will be prepared for the next restart.

The logs look good to me. And post the squid restart everything seems to be fine.
I just got some atlas tasks though so I assume they will kill at least one theory.
If I get another stuck one. Ill nuke the cache and also do a project reset to see if that solves the issue.

You may also insert the following line in your squid.conf and do a "squid -k reconfigure".

shutdown_lifetime 3 seconds

This avoids the 60 seconds default delay when you shutdown/restart squid but I'm not 100% sure if changing this timeout requires a squid -k restart. At least Squid will be prepared for the next restart.

Not sure where to stick it but this spot felt oh so right:

# You don't believe this is enough? For sure, it is!
cache_mem 192 MB
maximum_object_size_in_memory 24 KB
memory_replacement_policy heap GDSF

shutdown_lifetime 3 seconds

No idea what I'm doing. Is there an LHC Squid Care & Feeding Guide anywhere?

CentOs8-VM (RedHat):
systemctl stop squid in console.
This will take a few seconds (nearly 10 seconds). No more command is needed.