I'm going to try and fix the root cause for 4.5 - I've suspected what it is since early this year, but it's never personally been an issue, so it's rolled along for a long time.
Mark Sent from my iPhone On Sep 3, 2013, at 4:30 PM, Tim Vaillancourt <t...@elementspace.com> wrote: > Hey guys, > > I am looking into an issue we've been having with SolrCloud since the > beginning of our testing, all the way from 4.1 to 4.3 (haven't tested 4.4.0 > yet). I've noticed other users with this same issue, so I'd really like to > get to the bottom of it. > > Under a very, very high rate of updates (2000+/sec), after 1-12 hours we > see stalled transactions that snowball to consume all Jetty threads in the > JVM. This eventually causes the JVM to hang with most threads waiting on > the condition/stack provided at the bottom of this message. At this point > SolrCloud instances then start to see their neighbors (who also have all > threads hung) as down w/"Connection Refused", and the shards become "down" > in state. Sometimes a node or two survives and just returns 503s "no server > hosting shard" errors. > > As a workaround/experiment, we have tuned the number of threads sending > updates to Solr, as well as the batch size (we batch updates from client -> > solr), and the Soft/Hard autoCommits, all to no avail. Turning off > Client-to-Solr batching (1 update = 1 call to Solr), which also did not > help. Certain combinations of update threads and batch sizes seem to > mask/help the problem, but not resolve it entirely. > > Our current environment is the following: > - 3 x Solr 4.3.1 instances in Jetty 9 w/Java 7. > - 3 x Zookeeper instances, external Java 7 JVM. > - 1 collection, 3 shards, 2 replicas (each node is a leader of 1 shard and > a replica of 1 shard). > - Log4j 1.2 for Solr logs, set to WARN. This log has no movement on a good > day. > - 5000 max jetty threads (well above what we use when we are healthy), > Linux-user threads ulimit is 6000. > - Occurs under Jetty 8 or 9 (many versions). > - Occurs under Java 1.6 or 1.7 (several minor versions). > - Occurs under several JVM tunings. > - Everything seems to point to Solr itself, and not a Jetty or Java version > (I hope I'm wrong). > > The stack trace that is holding up all my Jetty QTP threads is the > following, which seems to be waiting on a lock that I would very much like > to understand further: > > "java.lang.Thread.State: WAITING (parking) > at sun.misc.Unsafe.park(Native Method) > - parking to wait for <0x00000007216e68d8> (a > java.util.concurrent.Semaphore$NonfairSync) > at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186) > at > java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834) > at > java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:994) > at > java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1303) > at java.util.concurrent.Semaphore.acquire(Semaphore.java:317) > at > org.apache.solr.util.AdjustableSemaphore.acquire(AdjustableSemaphore.java:61) > at > org.apache.solr.update.SolrCmdDistributor.submit(SolrCmdDistributor.java:418) > at > org.apache.solr.update.SolrCmdDistributor.submit(SolrCmdDistributor.java:368) > at > org.apache.solr.update.SolrCmdDistributor.flushAdds(SolrCmdDistributor.java:300) > at > org.apache.solr.update.SolrCmdDistributor.finish(SolrCmdDistributor.java:96) > at > org.apache.solr.update.processor.DistributedUpdateProcessor.doFinish(DistributedUpdateProcessor.java:462) > at > org.apache.solr.update.processor.DistributedUpdateProcessor.finish(DistributedUpdateProcessor.java:1178) > at > org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:83) > at > org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:135) > at org.apache.solr.core.SolrCore.execute(SolrCore.java:1820) > at > org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:656) > at > org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:359) > at > org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:155) > at > org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1486) > at > org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:503) > at > org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:138) > at > org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:564) > at > org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:213) > at > org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1096) > at > org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:432) > at > org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:175) > at > org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1030) > at > org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:136) > at > org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:201) > at > org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109) > at > org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) > at org.eclipse.jetty.server.Server.handle(Server.java:445) > at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:268) > at > org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:229) > at > org.eclipse.jetty.io.AbstractConnection$ReadCallback.run(AbstractConnection.java:358) > at > org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:601) > at > org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:532) > at java.lang.Thread.run(Thread.java:724)" > > Some questions I had were: > 1) What exclusive locks does SolrCloud "make" when performing an update? > 2) Keeping in mind I do not read or write java (sorry :D), could someone > help me understand "what" solr is locking in this case at > "org.apache.solr.util.AdjustableSemaphore.acquire(AdjustableSemaphore.java:61)" > when performing an update? That will help me understand where to look next. > 3) It seems all threads in this state are waiting for "0x00000007216e68d8", > is there a way to tell what "0x00000007216e68d8" is? > 4) Is there a limit to how many updates you can do in SolrCloud? > 5) Wild-ass-theory: would more shards provide more locks (whatever they > are) on update, and thus more update throughput? > > To those interested, I've provided a stacktrace of 1 of 3 nodes at this URL > in gzipped form: > https://s3.amazonaws.com/timvaillancourt.com/tmp/solr-jstack-2013-08-23.gz > > Any help/suggestions/ideas on this issue, big or small, would be much > appreciated. > > Thanks so much all! > > Tim Vaillancourt
