Details
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Bug
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Status: Resolved
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Normal
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Resolution: Fixed
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None
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None
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Normal
Description
Cluster was flooded with SSTables. A table had ~20000 sstables. Write requests started failing.
Steps to reproduce:
- Create cluster with 3 nodes
- Specify
memtable_heap_space_in_mb: 10
in cassandra.yaml
- Create table standard1 in keyspace1 (for the cassandra-stress tool) with the script create.cql
. Please note
compaction = {'class': 'SizeTieredCompactionStrategy', 'enabled': 'false'}i.e. compaction will be turned off for now.
- Populate node with data:
cassandra-stress write n=1000000000 -node 127.0.0.1
- After node was populated, put both read and write pressure on it:
cassandra-stress read n=1000000000 -node 127.0.0.1 cassandra-stress write n=1000000000 -node 127.0.0.1
- While still under pressure, enable LeveledCompactionStrategy
echo "ALTER TABLE keyspace1.standard1 WITH compaction = { 'class' : 'LeveledCompactionStrategy', 'sstable_size_in_mb' : 1 }; DESC keyspace1.standard1; exit" | bin/cqlsh;
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:
$ bin/nodetool cfstats
...
Table: standard1
SSTable count: 22637
SSTables in each level: [22651/4, 0, 0, 0, 0, 0, 0, 0, 0]
...
$ 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%
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):
"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)
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:
"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)
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Issue Links
- duplicates
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- Resolved
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- relates to
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- Resolved
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