[ejabberd] mod_muc_odbc performance/memory issues with room with massive set of affiliations

Michael Amundson michael at echobit.com
Sun Nov 18 22:34:50 MSK 2012

Evgeniy Khramtsov wrote:
> On 17.11.2012 14:57, Michael Amundson wrote:
>> Hi again, and apologies for all these ODBC-related questions I keep
>> raising.
>> I have a MUC with a rather large number of affiliations associated
>> with it (around 95,000). While migrating to mod_muc_odbc, I've
>> noticed that adding new affiliations to this MUC take around 12 to 15
>> seconds to complete, during which the CPU is spinning at nearly 100%...
> I did some improvements in the data serialization. Pushed into
> origin/2.1.x. The patch is also attached to this email for those who
> are interested.

Thanks! This cut the roundtrip time to add an affiliation to the MUC 
from 12s to 5s (consistent after several tests). Memory usage still 
bloats up by about the same amount as before, but perhaps that's related 
to me running a rather stale version of Erlang (R14A).

I'm still a bit curious why 95,000 affiliations hammers the server this 
hard--is serialization in Erlang just really intensive with large enough 

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