That means they are blocking for something to be added to the task queue On Mon, May 17, 2010 at 9:42 AM, Joost Ouwerkerk <jo...@openplaces.org> wrote: > At any given moment at least half of those threads are in the following > state; what does it represent? > Name: ROW-READ-STAGE:6 > State: WAITING on > java.util.concurrent.locks.abstractqueuedsynchronizer$conditionobj...@fea6030 > Total blocked: 44 Total waited: 479 > Stack trace: > sun.misc.Unsafe.park(Native Method) > java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) > java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925) > java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:358) > java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:947) > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907) > java.lang.Thread.run(Thread.java:619) > > On Mon, May 17, 2010 at 12:53 AM, Jonathan Ellis <jbel...@gmail.com> wrote: >> >> On Sun, May 16, 2010 at 2:52 PM, Joost Ouwerkerk <jo...@openplaces.org> >> wrote: >> > Meanwhile. I'm still getting TimedOutException errors when mapping this >> > 30-million row table, even when retrieving no data at all. It looks >> > like it >> > is related to disk activity on "hot" nodes (when the same cassandra node >> > has >> > to handle many concurrent requests for adjacent range slices). Using >> > 0.7 >> > trunk branch doesn't appear to alleviate it. CPU load is at about 25% >> > when >> > this happens. Is there some kind of synchronization that might prevent >> > the >> > same file from being scanned by multiple threads? >> >> No, but there's only `concurrent_reads` threads serving reads and if >> you have a lot of ops in the queue ahead of you then that would do it. >> (pending tasks in row stage under cassandra.concurrent jmx.) >> >> -- >> Jonathan Ellis >> Project Chair, Apache Cassandra >> co-founder of Riptano, the source for professional Cassandra support >> http://riptano.com > >
-- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
