That code has NOT changed since March 2011!

I've just tried with the following values:

WOWatchDogRequestTimeout = 120;
SOGoMailCustomFromEnabled = YES;
SOGoMaximumPingInterval = 3600;
SOGoMaximumSyncInterval = 3600;
SOGoInternalSyncInterval = 60;

and Apache proxy configuration:

ProxyPass /Microsoft-Server-ActiveSync http://127.0.0.1:20000/SOGo/Microsoft-Server-ActiveSync retry=0 connectiontimeout=5 timeout=3600

and it works as expected. The daemon was running well after 10 mins.

...
Dec 16 17:36:07 sogod [16855]: [WARN] <0x0x7fd1501225d0[WOWatchDogChild]> pid 16856 has been hanging in the same request for 10 minutes
Dec 16 17:37:07 sogod [16855]: [WARN] <0x0x7fd1501225d0[WOWatchDogChild]> pid 16856 has been hanging in the same request for 11 minutes
Dec 16 17:38:07 sogod [16855]: [WARN] <0x0x7fd1501225d0[WOWatchDogChild]> pid 16856 has been hanging in the same request for 12 minutes
...

I get repeated occurences (38 times between 0330 and 1030 today) of this sequence :

Dec 16 09:50:22 sogod [15628]: |SOGo| starting method 'OPTIONS' on uri '/SOGo/Microsoft-Server-ActiveSync?User=benjamin&DeviceId=B4389A49654394ACF8174149614DDA60&DeviceType=WP8'
2014-12-16 09:50:22.179 sogod[15628] -[WEClientCapabilities initWithRequest:]: Unknown WebClient: user-agent='MSFT-WP/8.10.12393'
Dec 16 09:50:22 sogod [15628]: |SOGo| request took 0.013008 seconds to execute
Dec 16 09:50:22 sogod [15628]: |SOGo| starting method 'POST' on uri '/SOGo/Microsoft-Server-ActiveSync?jREUBBC0OJpJZUOUrPgXQUlhTdpgBAAAAAADV1A4'
Dec 16 09:50:22 sogod [15628]: |SOGo| request took 0.001679 seconds to execute
Dec 16 09:50:22 sogod [15628]: |SOGo| starting method 'POST' on uri '/SOGo/Microsoft-Server-ActiveSync?jQkUBBC0OJpJZUOUrPgXQUlhTdpgBAAAAAADV1A4'
Dec 16 09:50:22 sogod [15628]: <0x0x7ffb8a20b110[NGImap4Client]> TLS started successfully.
Dec 16 09:50:23 sogod [15628]: |SOGo| request took 1.165617 seconds to execute
Dec 16 09:50:23 sogod [15628]: |SOGo| starting method 'POST' on uri '/SOGo/Microsoft-Server-ActiveSync?jQAUBBC0OJpJZUOUrPgXQUlhTdpgBAAAAAADV1A4'
Dec 16 09:51:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 1 minutes
Dec 16 09:52:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 2 minutes
Dec 16 09:53:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 3 minutes
Dec 16 09:54:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 4 minutes
Dec 16 09:55:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 5 minutes
Dec 16 09:56:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 6 minutes
Dec 16 09:57:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 7 minutes
Dec 16 09:58:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 8 minutes
Dec 16 09:59:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 9 minutes
Dec 16 10:00:23 sogod [18704]: [WARN] <0x0x7ffb890b3180[WOWatchDogChild]> pid 15628 has been hanging in the same request for 10 minutes
Dec 16 10:00:27 sogod [18704]: <0x0x7ffb890b3180[WOWatchDogChild]> child 15628 exited
Dec 16 10:00:27 sogod [18704]: <0x0x7ffb890b3180[WOWatchDogChild]> (terminated due to signal 11)
Dec 16 10:00:27 sogod [18704]: <0x0x7ffb88e38cd0[WOWatchDog]> child spawned with pid 16763

I have in sogo.conf :

WOWatchDogRequestTimeout = 120;

I have also added to the startup script (to see if it helps) :

DAEMON_OPTS="-WOWorkersCount $PREFORK -WOPidFile $PIDFILE -WOLogFile $LOGFILE -WOWatchDogRequestTimeout 120"

ps aux shows :

sogo 18737 0.0 0.0 429748 16364 ? Ss des.14 0:01 /usr/sbin/sogod -WOWorkersCount 30 -WOPidFile /var/run/sogo/sogo.pid -WOLogFile /var/log/sogo/sogo.log -WOWatchDogRequestTimeout 120

... and most importantly of all - the setup and sogo.conf file have not changed for a month or more.
It is the first time the WOWatchDogRequestTimeout has been ignored.
When first installing SOGo I started out with 10 minutes, but due to large mailboxes I have gradually been increasing this.
So this is not a sudden change on our part.

greping sogo.log shows NO "has been hanging for 11 minutes" etc., it always exits after 10 minutes.

What else can be causing this ?

The child existed with a segfault - signal 11. It was NOT terminated by the partent.

Attach using gdb to a "hanging child' and produce a stacktrace when that happens:

http://www.sogo.nu/fr/nc/support/faq/article/how-do-i-debug-sogo.html

Backtrace uploaded. Note that crash occured after about 20 minutes this time.

Same crash occurs after 10 minutes when same user uses Outlook 2013 with ActiveSync - same account/server etc.

Could you be running out of RAM?

I thought it was a memory issue, too, at first and set SxVMemLimit = 8192

But no, doesn't seem that way. There's still 4+ GB free when SOGOd process claims about 2 GB. And no OOM messages either.

It's the same server/setup I've been using since August, and it runs fine in production for other users on Thunderbird etc.

Try with 2.2.13 with the new SOGoMaximumSyncResponseSize configuration parameter.

Sorry, I see I should have responded to this issue instead of posting a new bug at 0003051.

But anyways, the issue persists in 2.2.13 with SOGoMaximumSyncResponseSize=10240.
Process stil claims about 2GB and there's free RAM on the server on exit.

Backtraces have been uploaded to 0003051.