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Jeff Jirsa commented on CASSANDRA-14069: ---------------------------------------- [~krummas] have time for another review? > Node stopped serving write requests when a table has a lot of sstables > ---------------------------------------------------------------------- > > Key: CASSANDRA-14069 > URL: https://issues.apache.org/jira/browse/CASSANDRA-14069 > Project: Cassandra > Issue Type: Bug > Components: Compaction > Reporter: Sergey Lapukhov > Assignee: Sergey Lapukhov > Attachments: CAS-14069.patch, afterPatch.svg, beforePatch.svg, > create.cql, stack.txt > > > Cluster was flooded with SSTables. A table had ~20000 sstables. Write > requests started failing. > Steps to reproduce: > * Create cluster with 3 nodes > * Specify > {noformat} > memtable_heap_space_in_mb: 10 > {noformat} > in cassandra.yaml > * Create table standard1 in keyspace1 (for the cassandra-stress tool) with > the script [^create.cql]. Please note > {noformat} compaction = {'class': 'SizeTieredCompactionStrategy', 'enabled': > 'false'} {noformat} > i.e. compaction will be turned off for now. > * Populate node with data: > {noformat} cassandra-stress write n=1000000000 -node 127.0.0.1 {noformat} > * After node was populated, put both read and write pressure on it: > {noformat} cassandra-stress read n=1000000000 -node 127.0.0.1 > cassandra-stress write n=1000000000 -node 127.0.0.1 {noformat} > * While still under pressure, enable LeveledCompactionStrategy > {code:java} echo "ALTER TABLE keyspace1.standard1 WITH compaction = { > 'class' : 'LeveledCompactionStrategy', 'sstable_size_in_mb' : 1 }; DESC > keyspace1.standard1; exit" | bin/cqlsh; {code} > *Results:* > Write requests failing. > 'bin/nodetool cfstats' and 'bin/nodetool compactionstats' commands hanging, > if issued from the node running cassandra-stress tool. > If issued from another node: > {noformat} > $ bin/nodetool cfstats > ... > Table: standard1 > SSTable count: 22637 > SSTables in each level: [22651/4, 0, 0, 0, 0, 0, 0, 0, 0] > ... > {noformat} > {noformat} > $ bin/nodetool compactionstats > pending tasks: 12656 > id compaction type keyspace > table completed total unit progress > 935bbc00-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 59556014 59557860 bytes 100.00% > a29ee660-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 80432114 742151655 bytes 10.84% > 9766e400-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 58891604 58893215 bytes 100.00% > 9cdc9880-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 20289449 20290800 bytes 99.99% > 90f98910-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 59689824 59695545 bytes 99.99% > 986ede20-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 40598594 40598820 bytes 100.00% > 9cd322a0-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 > standard1 60756739 60766660 bytes 99.98% > {noformat} > Special note about 'bin/nodetool compactionstats' - picture above is quite > typical for this issue. I.e. compaction tasks manage to make it through, but > hinder near the full completion (around 99.9 %). > Maybe the root of the problem is in this thread (see [^stack.txt]): > {noformat} > "CompactionExecutor:1748" #4649 daemon prio=1 os_prio=4 > tid=0x00007f35a0096100 nid=0x65f6 runnable [0x00007f3228bce000] > java.lang.Thread.State: RUNNABLE > at org.apache.cassandra.dht.AbstractBounds.<init>(AbstractBounds.java:53) > at org.apache.cassandra.dht.Bounds.<init>(Bounds.java:42) > at > org.apache.cassandra.db.compaction.LeveledManifest.overlapping(LeveledManifest.java:562) > at > org.apache.cassandra.db.compaction.LeveledManifest.overlapping(LeveledManifest.java:549) > at > org.apache.cassandra.db.compaction.LeveledManifest.getCandidatesFor(LeveledManifest.java:624) > at > org.apache.cassandra.db.compaction.LeveledManifest.getCompactionCandidates(LeveledManifest.java:378) > - locked <0x000000070d4c3bc8> (a > org.apache.cassandra.db.compaction.LeveledManifest) > at > org.apache.cassandra.db.compaction.LeveledCompactionStrategy.getNextBackgroundTask(LeveledCompactionStrategy.java:105) > - locked <0x000000070d6cb2c8> (a > org.apache.cassandra.db.compaction.LeveledCompactionStrategy) > at > org.apache.cassandra.db.compaction.CompactionStrategyManager.getNextBackgroundTask(CompactionStrategyManager.java:102) > - locked <0x00000006467268b8> (a > org.apache.cassandra.db.compaction.CompactionStrategyManager) > at > org.apache.cassandra.db.compaction.CompactionManager$BackgroundCompactionCandidate.run(CompactionManager.java:258) > at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) > at java.util.concurrent.FutureTask.run(FutureTask.java:266) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) > at > org.apache.cassandra.concurrent.NamedThreadFactory.lambda$threadLocalDeallocator$0(NamedThreadFactory.java:79) > at > org.apache.cassandra.concurrent.NamedThreadFactory$$Lambda$4/1671507048.run(Unknown > Source) > at java.lang.Thread.run(Thread.java:748) > {noformat} > As I see it, thread is running a cycle, which has O(n^2) dependency on the > number of SSTables, while still holding the lock. > Say this one: > {noformat} > "CompactionExecutor:1743" #4644 daemon prio=1 os_prio=4 > tid=0x00007f35a01591a0 nid=0x65f1 waiting for monitor entry > [0x00007f322d016000] > java.lang.Thread.State: BLOCKED (on object monitor) > at > org.apache.cassandra.db.compaction.CompactionStrategyManager.handleNotification(CompactionStrategyManager.java:252) > - waiting to lock <0x00000006467268b8> (a > org.apache.cassandra.db.compaction.CompactionStrategyManager) > at > org.apache.cassandra.db.lifecycle.Tracker.notifyDeleting(Tracker.java:448) > at > org.apache.cassandra.db.lifecycle.LogTransaction.obsoleted(LogTransaction.java:161) > at > org.apache.cassandra.db.lifecycle.Helpers.prepareForObsoletion(Helpers.java:134) > at > org.apache.cassandra.db.lifecycle.LifecycleTransaction.doPrepare(LifecycleTransaction.java:199) > at > org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173) > at > org.apache.cassandra.io.sstable.SSTableRewriter.doPrepare(SSTableRewriter.java:376) > at > org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173) > at > org.apache.cassandra.db.compaction.writers.CompactionAwareWriter.doPrepare(CompactionAwareWriter.java:84) > at > org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173) > at > org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.finish(Transactional.java:184) > at > org.apache.cassandra.db.compaction.writers.CompactionAwareWriter.finish(CompactionAwareWriter.java:94) > at > org.apache.cassandra.db.compaction.CompactionTask.runMayThrow(CompactionTask.java:206) > at > org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28) > at > org.apache.cassandra.db.compaction.CompactionTask.executeInternal(CompactionTask.java:89) > at > org.apache.cassandra.db.compaction.AbstractCompactionTask.execute(AbstractCompactionTask.java:61) > at > org.apache.cassandra.db.compaction.CompactionManager$BackgroundCompactionCandidate.run(CompactionManager.java:264) > at > java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) > at java.util.concurrent.FutureTask.run(FutureTask.java:266) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) > at > org.apache.cassandra.concurrent.NamedThreadFactory.lambda$threadLocalDeallocator$0(NamedThreadFactory.java:79) > at > org.apache.cassandra.concurrent.NamedThreadFactory$$Lambda$4/1671507048.run(Unknown > Source) > at java.lang.Thread.run(Thread.java:748) > {noformat} -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org