looks like reads are backing up, which in turn is making deserialize back up
On Sun, May 23, 2010 at 4:25 AM, Ran Tavory <ran...@gmail.com> wrote: > Here's tpstats on a server with traffic that I think will get OOM shortly. > We have 4k pending reads and 123k pending at MESSAGE-DESERIALIZER-POOL > Is there something I can do to prevent that? (other than adding RAM...) > Pool Name Active Pending Completed > FILEUTILS-DELETE-POOL 0 0 55 > STREAM-STAGE 0 0 6 > RESPONSE-STAGE 0 0 0 > ROW-READ-STAGE 8 4088 7537229 > LB-OPERATIONS 0 0 0 > MESSAGE-DESERIALIZER-POOL 1 123799 22198459 > GMFD 0 0 471827 > LB-TARGET 0 0 0 > CONSISTENCY-MANAGER 0 0 0 > ROW-MUTATION-STAGE 0 0 14142351 > MESSAGE-STREAMING-POOL 0 0 16 > LOAD-BALANCER-STAGE 0 0 0 > FLUSH-SORTER-POOL 0 0 0 > MEMTABLE-POST-FLUSHER 0 0 128 > FLUSH-WRITER-POOL 0 0 128 > AE-SERVICE-STAGE 1 1 8 > HINTED-HANDOFF-POOL 0 0 10 > > On Sat, May 22, 2010 at 11:05 PM, Ran Tavory <ran...@gmail.com> wrote: >> >> The message deserializer has 10m pending tasks before the oom. What do you >> think makes the message deserializer blow up? I'd suspect that when it goes >> up to 10m pending tasks, don't know how much mem a task actually takes up, >> but they may consume a lot of memory. Is there a setting I need to tweak? >> (or am I barking at the wrong tree?). >> I'll add the counters >> from http://github.com/jbellis/cassandra-munin-plugins but I already have >> most of them monitored, so I attached the graphs of the ones that seemed the >> most suspicious in the previous email. >> The system keyspace and HH CF don't look too bad, I think, here they are: >> Keyspace: system >> Read Count: 154 >> Read Latency: 0.875012987012987 ms. >> Write Count: 9 >> Write Latency: 0.20055555555555554 ms. >> Pending Tasks: 0 >> Column Family: LocationInfo >> SSTable count: 1 >> Space used (live): 2714 >> Space used (total): 2714 >> Memtable Columns Count: 0 >> Memtable Data Size: 0 >> Memtable Switch Count: 3 >> Read Count: 2 >> Read Latency: NaN ms. >> Write Count: 9 >> Write Latency: 0.011 ms. >> Pending Tasks: 0 >> Key cache capacity: 1 >> Key cache size: 1 >> Key cache hit rate: NaN >> Row cache: disabled >> Compacted row minimum size: 203 >> Compacted row maximum size: 397 >> Compacted row mean size: 300 >> Column Family: HintsColumnFamily >> SSTable count: 1 >> Space used (live): 1457 >> Space used (total): 4371 >> Memtable Columns Count: 0 >> Memtable Data Size: 0 >> Memtable Switch Count: 0 >> Read Count: 152 >> Read Latency: 0.369 ms. >> Write Count: 0 >> Write Latency: NaN ms. >> Pending Tasks: 0 >> Key cache capacity: 1 >> Key cache size: 1 >> Key cache hit rate: 0.07142857142857142 >> Row cache: disabled >> Compacted row minimum size: 829 >> Compacted row maximum size: 829 >> Compacted row mean size: 829 >> >> >> >> >> On Sat, May 22, 2010 at 4:14 AM, Jonathan Ellis <jbel...@gmail.com> wrote: >>> >>> Can you monitor cassandra-level metrics like the ones in >>> http://github.com/jbellis/cassandra-munin-plugins ? >>> >>> the usual culprit is usually compaction but your compacted row size is >>> small. nothing else really comes to mind. >>> >>> (you should check system keyspace too tho, HH rows can get large) >>> >>> On Fri, May 21, 2010 at 2:36 PM, Ran Tavory <ran...@gmail.com> wrote: >>> > I see some OOM on one of the hosts in the cluster and I wonder if >>> > there's a >>> > formula that'll help me calculate what's the required memory setting >>> > given >>> > the parameters x,y,z... >>> > In short, I need advice on: >>> > 1. How to set up proper heap space and which parameters should I look >>> > at >>> > when doing so. >>> > 2. Help setting up an alert policy and define some counter measures or >>> > sos >>> > steps an admin can take to prevent further degradation of service when >>> > alerts fire. >>> > The OOM is at the row mutation stage and it happens after extensive GC >>> > activity. (log tail below). >>> > The server has 16G physical ram and java heap space 4G. No other >>> > significant >>> > processes run on the same server. I actually upped the java heap space >>> > to 8G >>> > but it OOMed again... >>> > Most of my settings are the defaults with a few keyspaces and a few CFs >>> > in >>> > each KS. Here's the output of cfstats for the largest and most heavily >>> > used >>> > CF. (currently reads/writes are stopped but data is there). >>> > Keyspace: outbrain_kvdb >>> > Read Count: 3392 >>> > Read Latency: 160.33135908018866 ms. >>> > Write Count: 2005839 >>> > Write Latency: 0.029233923061621595 ms. >>> > Pending Tasks: 0 >>> > Column Family: KvImpressions >>> > SSTable count: 8 >>> > Space used (live): 21923629878 >>> > Space used (total): 21923629878 >>> > Memtable Columns Count: 69440 >>> > Memtable Data Size: 9719364 >>> > Memtable Switch Count: 26 >>> > Read Count: 3392 >>> > Read Latency: NaN ms. >>> > Write Count: 1998821 >>> > Write Latency: 0.018 ms. >>> > Pending Tasks: 0 >>> > Key cache capacity: 200000 >>> > Key cache size: 11661 >>> > Key cache hit rate: NaN >>> > Row cache: disabled >>> > Compacted row minimum size: 302 >>> > Compacted row maximum size: 22387 >>> > Compacted row mean size: 641 >>> > I'm also attaching a few graphs of "the incidenst" I hope they help. >>> > From >>> > the graphs it looks like: >>> > 1. message deserializer pool is behind so maybe taking too much mem. If >>> > graphs are correct, it gets as high as 10m pending before crash. >>> > 2. row-read-stage has a high number of pending (4k) so first of all - >>> > this >>> > isn't good for performance whether it caused the oom or not, and >>> > second, >>> > this may also have taken up heap space and caused the crash. >>> > Thanks! >>> > INFO [GC inspection] 2010-05-21 00:53:25,885 GCInspector.java (line >>> > 110) GC >>> > for ConcurrentMarkSweep: 10819 ms, 939992 reclaimed leaving 4312064504 >>> > used; >>> > max is 4431216640 >>> > INFO [GC inspection] 2010-05-21 00:53:44,605 GCInspector.java (line >>> > 110) GC >>> > for ConcurrentMarkSweep: 9672 ms, 673400 reclaimed leaving 4312337208 >>> > used; >>> > max is 4431216640 >>> > INFO [GC inspection] 2010-05-21 00:54:23,110 GCInspector.java (line >>> > 110) GC >>> > for ConcurrentMarkSweep: 9150 ms, 402072 reclaimed leaving 4312609776 >>> > used; >>> > max is 4431216640 >>> > ERROR [ROW-MUTATION-STAGE:19] 2010-05-21 01:55:37,951 >>> > CassandraDaemon.java >>> > (line 88) Fatal exception in thread >>> > Thread[ROW-MUTATION-STAGE:19,5,main] >>> > java.lang.OutOfMemoryError: Java heap space >>> > ERROR [Thread-10] 2010-05-21 01:55:37,951 CassandraDaemon.java (line >>> > 88) >>> > Fatal exception in thread Thread[Thread-10,5,main] >>> > java.lang.OutOfMemoryError: Java heap space >>> > ERROR [CACHETABLE-TIMER-2] 2010-05-21 01:55:37,951 CassandraDaemon.java >>> > (line 88) Fatal exception in thread Thread[CACHETABLE-TIMER-2,5,main] >>> > java.lang.OutOfMemoryError: Java heap space >>> > >>> >>> >>> >>> -- >>> 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
