[horde] Horde Webmail auf Virtuozzo Problem?

[Lutz Jänicke]

On 30.03.2016 21:23, Erling Preben Hansen wrote:
>  Citat af Lutz Jänicke <lutz at lutz-jaenicke.de>:
>
>> Hi!
>>
>> Since upgrading to the latest Horde Webmail 5.2.13 last week I am
>> experiencing problems with my virtual Linux server. The "numothersocks"
>> resource which limits the amount of open UNIX sockets fills up. lsof
>> indicates that there are a lot of connections open to gam_server which
>> is responsible to monitor changes to the file system to inform IMAP
>> about new mails coming in.
>>
>> System information:
>> * Ubuntu 14.04 (maintained with latest updates)
>> * Courier IMAP
>> * Virtual Server at Hosteurope with Virtuozzo
>> * Limit to numothersocks: 550 (which seems far too low to make sense but
>> did not cause problems before)
>> * Number of users is only five (with ActiveSync)
>>
>> Since the system was working fine until the last upgrade and no other
>> components in the area of email/IMAP etc was touched I assume the issue
>> is conntect with the Horde upgrade... I however may be wrong.
>> How can I track down this issue?
>>
>
>  Hey
> Had the same trouble some time ago.
> You can change the configuration of the gam_server check time from
> several times pr secund to 1 time pr 10 secund if you really need it.
>
> I can not remember where i did it.
>
>  I found this on a Rhel forum:
> ------
>  What is gam server ? How to stop?
>
>     It is a known bug in RHEL.
>     It hogs all the processors and some time claims 99% of CPU time.
> This type of behavior is mainly contributed to screen saver. As We are
> run our server in INIT 3 level,so screen saver is not the culprit in
> our case.
>     Gam_server is the running instance name of “gemin” which is by
> default loaded with RHEL.Its the successor of FAM (File Alteration
> Module).FAM (or gam_server) is used to decrease CPU cycle by
> effectively implementing Locking/Unlocking file handles. When used
> with IMAP , it is claimed that it will ease shared folder implementation.
>
> In our scenario,huge number of gam_servers(sometimes > 350) were
> running and virtually doing nothing.At the same time, these processes
> use to fire mails to root which could not be delivered thus giving
> unnecessary load to Postfix(these mails were lying in Q and postfix
> tries to resend Q’ed mails after certain intervals)Courier-IMAP has
> been compiled with FAM module so it was the part and parcel of it. We
> have not implemented shared folders so I toggled two parameters of
> imapd.Two parameters IMAP_USELOCKS and IMAP_ENHANCEDIDLE are used to
> implement shared folders.If you not interested in shared folders(Some
> webmail client like squirrelmail lets you to implement shared folder )
> you can disable these two parameters.
>
> IMAP_USELOCKS=0
>
> IMAP_ENHANCEDIDLE=0
>
> Changed (toggled parameter) is written in RED BOLD. Both these
> parameters are used in conjunction with Shared Folder Implementation.
>
> After restarting imapd,no gam_server will be spawned.

Thanks, I will look into your recommendation.

For the time being I "solved" the problem by upgrading to a larger
virtual machine version providing 750 sockets. I was at 70% disk usage
anyway.
As life is the maximum of numothersock observed is now below 400 but I
am not sure all clients are on...

Best regards,
    Lutz
> ------
>
> /Erling
>