[squid-users] Proper separation of multiple squid instances on the same machine

[Alex Rousskov]

On 11/28/19 4:34 PM, Robert Senger wrote:

> a couple of week ago I've separated a rather complex squid installation
> into two instances running on the same machine.
> 
> The setup of these two instances is almost identical, despite different
> tcp_outgoing_address and stuff like that.
> 
> All files on disk and all listening ports are set to different paths /
> values, so the instances should not interfere with each other. 
> 
> However, today I realized that squid creates files in /dev/shm:
> 
> root at prokyon:/dev/shm# ls -l
> insgesamt 2292
> -rw-------. 1 proxy    proxy          8 Nov 28 22:27 squid-cf__metadata.shm
> -rw-------. 1 proxy    proxy       8216 Nov 28 22:27 squid-cf__queues.shm
> -rw-------. 1 proxy    proxy         36 Nov 28 22:27 squid-cf__readers.shm
> -rw-------. 1 proxy    proxy    2103672 Nov 28 22:27 squid-tls_session_cache.shm
> 
> These files are created when the first instance starts. When the second
> instance starts, the files get updated/recreated (new mtime/ctime). 
> 
> When any of the running instances is stopped, the files are deleted.
> 
> So, the two instances collide here.



> My questions:

> 1. Is this a problem?

Yes.


> 2. If so, what must I do?

Use different service names for different Squid instances running
concurrently on the same machine. The service name is specified on the
command line using "squid -n".

AFAICT, this trick is poorly documented and is not supported on some
platforms, but I hope it works in your environment.


HTH,

Alex.