On 2025-03-07 06:50, Andrey K wrote:
Squid Cache: Version 6.13
Service Name: squid
Squid Cache: Version 6.10
Service Name: squid
# the first instance
1318 DEL ... 30205 /dev/shm/squid-cf__queues.shm
1318 DEL ... 30206 /dev/shm/squid-cf__readers.shm
1318 DEL ... 30204 /dev/shm/squid-cf__metadata.shm
1318 8u ... 8 30204 /dev/shm/squid-cf__metadata.shm (deleted)
1318 9u ... 525572 30205 /dev/shm/squid-cf__queues.shm (deleted)
1318 10u ... 136 30206 /dev/shm/squid-cf__readers.shm (deleted)
# the second instance
1514 mem ... 2093368 31497 /dev/shm/squid-tls_session_cache.shm
1514 mem ... 525572 31495 /dev/shm/squid-cf__queues.shm
1514 mem ... 136 31496 /dev/shm/squid-cf__readers.shm
1514 mem ... 8 31494 /dev/shm/squid-cf__metadata.shm
1514 6u ... 8 31494 /dev/shm/squid-cf__metadata.shm
1514 7u ... 525572 31495 /dev/shm/squid-cf__queues.shm
1514 8u ... 136 31496 /dev/shm/squid-cf__readers.shm
1514 9u ... 2093368 31497 /dev/shm/squid-tls_session_cache.shm
As suspected, these two Squid instances use the same shared memory
segments (e.g., /dev/shm/squid-cf*). Such shared use violates critical
code assumptions and results in undefined behavior.
Maybe I'm not experiencing any difficulties because I have caching turned off on
both instances?
Well, you _are_ experiencing at least one difficulty -- the assertion
that started this email thread. If you have fully disabled caching, the
difficulties you experience should not include cache corruption.
However, it looks like at least one of the two instances does cache TLS
sessions (in /dev/shm/squid-tls_session_cache.shm). If both instances do
that, then all bets are off!
FWIW, related future Squid improvements may include:
* Detecting such shared memory segments clashes; refusing to start.
* Disabling shared memory use when caching is completely disabled.
Quality pull requests welcome.
Cheers,
Alex.
чт, 6 мар. 2025 г. в 17:11, Alex Rousskov:
On 2025-03-06 08:59, Amos Jeffries wrote:
> On 6/03/25 19:17, Andrey K wrote:
>> Hello,
>>
>> I have a similar configuration: two SMP squids running on the
same OEL
>> host.
>>
>> They were built with different configurations: with different
>> installation path prefixes and different names of binary files:
squid
>> and squid.user and they listen to different ports.
>> They are launched from two different services:squid.service and
>> squid.user.service with the service Type=forking:
>>
>> ExecStart=/usr/sbin/squid -sYC
>> ExecStart=/sbin/squid.user -f /etc/squid.user/squid.conf
>>
>> I have not experienced any troubles with this configuration yet.
>>
>> /> Please be aware that "squid -n ..." is a REQUIREMENT for running/
>> /multiple Squid instances on the same machine regardless of what
features
>> are used./
>>
>> Could you please tell me if I should use the -n option in the
>> ExecStart strings?
>> The arguments of the options should be the service names?
>>
>> ExecStart=/usr/sbin/squid -sYC -n squid.service
>> ExecStart=/sbin/squid.user -f /etc/squid.user/squid.conf -n
>> squid.user.service
>>
> Yes you should. The different ./configure options has helped you
avoid
> major issues, but some may still appear.
I agree. Moreover, I do not understand how your two SMP Squids could
work correctly without distinct service names because (on OEL) I would
expect them to share the same shared memory segments (which they must
not do to remain distinct instances).
What is your Squid version? Can you tell how your Squids name their
shared memory segment "files"? For example, on some Linux OSes, those
segments could be in /var/run/shm/ with names like
squid-tr_map_anchors.shm and squid-tr_spaces.shm.
Thank you,
Alex.
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