Hi Ning, the correlation between couchjs and HTTP requests is that whenever a request needs couchjs for anything, it will use one that is around and idle. When CouchDB starts, none are idle and it will for and exec a new couchjs process. A couchjs process is not idle when a request is using it. So for every concurrent request, you will get a new fork & exec of a couchjs process.
I haven't looked at the current implementation in a while, but we should look into implementing some configurable ceiling that can't be crossed with more fork & exec. Requests then could either wait until a couchjs is idle and eventually timeout if none get freed or they could get served a Service Unavailable (503) — That behaviour should also be configurable. CCing dev@ to see if we can get more feedback on this. Cheers Jan -- On 15 Apr 2011, at 20:16, Ning Tan wrote: > A while back there was a post about stray couchjs processes that had > no apparent resolution. A similar situation happened in our > environment that resulted in hundreds of couchjs processes, which > caused out-of-memory problems for the server. > > We are investigating the cause and would appreciate any help in > pinpointing the problem. One thing that was curious to me is, how many > couchjs processes are needed to support concurrent requests. I > couldn't reproduce a large number of couchjs processes in my local > environment. It seems that all my view/filter requests were handled by > just one couchjs process. > > The environment that had problems was using 1.0.1. I've been testing > locally with 1.0.2. Would that make any difference? > > Also, the problematic environment had proxies sitting in front of the > couch boxes, so that's another variance in our analysis. But it's hard > to tell without knowing the relationship/cardinality between an HTTP > connection and a couchjs process. In the original post, connections > not properly closed were hinted as a potential culprit. However, it's > still unclear to me how mishandled HTTP connections can result in > multiple couchjs processes. If I'm not mistaken, couchjs only talks > via stdin/stdout and is not handling a connection directly. > > Sorry if this question doesn't have enough information. We are still > in very early stages of our analysis and don't have a lot of leads > yet. > > Thanks!
