[Topaz-dev] [Topaz-pubapp-dev] Mulgara Performance Woes

[Russell Uman]

> > in that case, perhaps the better route would be to reduce 
> maxThreads 
> > on the pub-app side.
> 
> Not neccessarily. A lot of hits on the pub-app should be 
> served from the cache without needing to hit mulgara at all, 
> so it makes perfect sense to have many more threads on the 
> pub-app side (though if the cache is all memory based, that 
> implies the requests will be purely cpu-bounds, which in turn 
> also means that extra threads don't help performance, but 
> instead only act as buffers when the number of requests spike).

except what we're seeing is that, once mulgara slows, all the threads on
the pub-app end up waiting on mulgara.

we've got maxThreads=150 on each pub-app.
when the stack is hung, mulgara's got 300 threads waiting.

> In the short term fix the caching. Mulgara's load was very 
> little before this upgrade (typically 3 - 4% cpu, IIRC), so 
> this sort of jump is odd to say the least.

how long ago did you last check? we've added 5 journals since launch,
and we're up to >3000 articles. is there a specific point that you saw a
jump or are we comparing now to awhile ago?

> > i know that we can't squeeze any more juice out of mulgara 
> until 0.9.
> > however, i do think we should be able to find a way to gracefully 
> > return
> > 503 to the client when mulgara is slow, rather than piling up and 
> > abandoning mulgara sessions so that the whole stack is hung.
> 
> How about limiting the number of sessions opened on mulgara - 
> that should be easy enough to add our wrapper that opens 
> mulgara sessions.
> Then set the limit to 5 or 10 or something.

sounds reasonable...will add to #812...

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
This email is confidential to the intended recipient. If you have received it in error, please notify the sender and delete it from your system. Any unauthorized use, disclosure or copying is not permitted. The views or opinions presented are solely those of the sender and do not necessarily represent those of Public Library of Science unless otherwise specifically stated. Please note that neither Public Library of Science nor any of its agents accept any responsibility for any viruses that may be contained in this e-mail or its attachments and it is your responsibility to scan the e-mail and attachments (if any).