So far I have been using gchisto to view the gc-log. In my last RS disconnection, I saw a total GC about 457 seconds. But individually, the max is 1340 ms, min is 0.527ms, avg is 48ms.
The RS disconnection might be due to other reasons. I think J-D has been digging that. thanks zhenyu On Mon, Nov 30, 2009 at 9:22 PM, stack <[email protected]> wrote: > I suppose up to this I thought it a given for any java application that > wants to do realtime whether a webserver or search application but yeah, we > should do more to highlight the import of GC tuning especially when failure > to do so can be relatively catastrophic (A RegionServer self-shutting > itself > down). Ryan in particular has been doing a bunch of talking up of the > topic > (He did our performance tuning wiki page too). We could start up a list > of > use cases and the tunings that helped alleviate GC woes for a particular > cluster profile and loading (So we'd have something to present at BAHUG? > Do > you know who we might talk to regards pauses in the MR/HDFS team Patrick? > We were introduced to the NameNode Tuner once... we should talk to him > again). It does seem to be a problem where one tuning does not suit all > deploys. > > Regards Zhenyu's case, there is still work to do IMO. What I saw in his > logs was a failed promotion from parnew, something that could be helped > starting CMS collection earlier (among other things). Hes also still on an > older version of the JVM. While things are not timing out at the moment, > IMO its still 'broke' if it has such long pauses (Zhenyu, in your GC logs, > are you seeing 4 minutes pause?). Ryan would argue these are inevitable > with CMS -- but at least in the one case that I saw some twiddling would > seem to help. > > Thanks Patrick, > St.Ack >
