Am 03.01.2011 13:21, schrieb Sergiu Dumitriu: > On 01/03/2011 12:38 PM, Andreas Hahn wrote: >> Hi XWiki users, >> >> fwiw I just want to share my experiences and observations with XWiki >> instance running out of memory. >> >> I was having a hard time to track this down but in the end I could >> successfully isolate the problem. >> For quite some time my XWiki instance was getting unresponsive to >> requests sooner or later. >> >> The Wiki was hosted on a VirtualBox VM and in most cases the VM guest >> was just freezing and needed to be restarted leaving no usable traces in >> the logs. In some cases I even found JVM crash reports so I first >> checked different JVMs and VirtualBox versions (PUEL and OSE licences). >> >> I had no success with this approach and so I moved the XWiki directly to >> a host environment (Ubuntu 10.10). I added Server instrumentation >> (VisualVM) but still the wiki got down after a while. Surprisingly the >> system was hanging although in many cases there was even enough memory >> available (I checked different VM settings up to 4GB). >> Finally a VisualVM thread dump showed what happened: >> When the robots came visiting my service they query a large number of >> pages and among them was one user-url: >> .../XWiki/someUser which ran into an infinite looping condition when >> rendering the page. >> I don't know how this could happen but as a result the whole memory was >> consumed and partly released afterwards so it seemed that there is still >> enough space available. Once this happened however the Webserver needed >> to be restarted because it wasn't responsive any more. >> Since I have deleted this user account everything is running ok for a >> couple of days now - I still have to move the service back into the >> VirtualBox guest VM. >> >> What puzzles me finally that its possible that one single request can >> kill the service by going into an infinte rendering loop. >> I would have thought that at some level there is a depth limit to >> prevent such conditions. > Normally, there are recursion checks in different places, like velocity > macros can be nested to at most 20 levels (100 in 3.0). What would help > is exporting the user profile as XAR and uploading it somewhere so that > we can see what's causing this specific problem. > > Ok, thanks for your support offer. I'll see if I can restore the old user > profile. I've created a new one with the same name in the meantime. >> Hope these observations help someone though .... >
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