Running multiple sync_clients
simon.matter at invoca.ch
Fri Nov 19 14:11:38 EST 2010
> Bron Gondwana wrote:
>> On Thu, Nov 18, 2010 at 12:58:10PM -0500, Michael D. Sofka wrote:
>>> Is it safe to run multiple sync_clients? Is there an advantage to
>>> doing so?
>>> I had to restart sync_client once. After later restarting cyrus two
>>> sync_clients were running, and appeared to do well together. Still, I
>>> stopped the old process out of caution.
>> What version? In 2.3.x, the sync_server will obtain a lock, so you can
>> only run one sync_server at a time. This means the sync_clients will
>> take it in turns sending data.
> 2.3.16. This description fits what I was seeing.
>> In 2.4, there is no global locking - just locks on each mailbox. So
>> possible for two sync_clients to run at the same time. There is a
>> possibility this will lead to the same data being sent twice. It won't
>> cause corruption, but it will cause excess IO!
>> Are you sure it's actually two sync_client instances? In every released
>> version, sync_client forks immediately upon starting and then forks
>> to actually send data.
> Yes. There were a total of 4 sync processes. Two parents, each with a
> child worker. The logs showed two sync_client processes taking turns.
>> Which is a problem because it opens the BDB environment once and closes
>> many times. So I've now changed it on my development branch to not fork
>> the second time, but just keep it all in once process. We'll see if
>> are actually any memory leaks left!
> Another question I have is what are /var/lib/imap/db/*? File says they
> are Berkeley dbs, but I thought all databases were skiplist in this
> release. I can't find the configuration options associated with this
That's not true for 2.3.16. Some db's are still BDB by default in vanilla
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