Severin Leonhardt created CASSANDRA-10815:
---------------------------------------------
Summary: WrappingCompactionStrategy can block others when there
are lots of sstables
Key: CASSANDRA-10815
URL: https://issues.apache.org/jira/browse/CASSANDRA-10815
Project: Cassandra
Issue Type: Bug
Components: Compaction
Reporter: Severin Leonhardt
We observe {{nodetool compactionstats}} hanging when there are a lot of
SSTables in one table. We have about 30.000 SSTables most likely created by an
incremental repair (why it's that many is still a mystery to us).
Looking at the stacktraces of some selected threads it becomes apparent that a
single CompactionExecutor blocks several other threads:
{noformat}
"CompactionExecutor:4065" - Thread t@282454
java.lang.Thread.State: RUNNABLE
at java.util.TimSort.binarySort(TimSort.java:292)
at java.util.TimSort.sort(TimSort.java:235)
at java.util.Arrays.sort(Arrays.java:1512)
at java.util.ArrayList.sort(ArrayList.java:1454)
at java.util.Collections.sort(Collections.java:175)
at
org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy.trimToThresholdWithHotness(SizeTieredCompactionStrategy.java:139)
at
org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy.mostInterestingBucket(SizeTieredCompactionStrategy.java:119)
at
org.apache.cassandra.db.compaction.LeveledManifest.getSSTablesForSTCS(LeveledManifest.java:360)
at
org.apache.cassandra.db.compaction.LeveledManifest.getCompactionCandidates(LeveledManifest.java:318)
- locked <25446e7b> (a
org.apache.cassandra.db.compaction.LeveledManifest)
at
org.apache.cassandra.db.compaction.LeveledCompactionStrategy.getMaximalTask(LeveledCompactionStrategy.java:101)
at
org.apache.cassandra.db.compaction.LeveledCompactionStrategy.getNextBackgroundTask(LeveledCompactionStrategy.java:90)
- locked <33506169> (a
org.apache.cassandra.db.compaction.LeveledCompactionStrategy)
at
org.apache.cassandra.db.compaction.WrappingCompactionStrategy.getNextBackgroundTask(WrappingCompactionStrategy.java:77)
- locked <31924612> (a
org.apache.cassandra.db.compaction.WrappingCompactionStrategy)
at
org.apache.cassandra.db.compaction.CompactionManager$BackgroundCompactionCandidate.run(CompactionManager.java:230)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{noformat}
Because this thread has locked <31924612> (a
org.apache.cassandra.db.compaction.WrappingCompactionStrategy) the following
threads are blocked:
{noformat}
"CompactionExecutor:4064" - Thread t@282337
java.lang.Thread.State: BLOCKED
at
org.apache.cassandra.db.compaction.WrappingCompactionStrategy.getNextBackgroundTask(WrappingCompactionStrategy.java:72)
- waiting to lock <31924612> (a
org.apache.cassandra.db.compaction.WrappingCompactionStrategy) owned by
"CompactionExecutor:4065" t@282454
at
org.apache.cassandra.db.compaction.CompactionManager$BackgroundCompactionCandidate.run(CompactionManager.java:230)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{noformat}
{noformat}
"MemtableFlushWriter:2431" - Thread t@283411
java.lang.Thread.State: BLOCKED
at
org.apache.cassandra.db.compaction.WrappingCompactionStrategy.handleNotification(WrappingCompactionStrategy.java:250)
- waiting to lock <31924612> (a
org.apache.cassandra.db.compaction.WrappingCompactionStrategy) owned by
"CompactionExecutor:4065" t@282454
at org.apache.cassandra.db.DataTracker.notifyAdded(DataTracker.java:518)
at
org.apache.cassandra.db.DataTracker.replaceFlushed(DataTracker.java:178)
at
org.apache.cassandra.db.compaction.AbstractCompactionStrategy.replaceFlushed(AbstractCompactionStrategy.java:234)
at
org.apache.cassandra.db.ColumnFamilyStore.replaceFlushed(ColumnFamilyStore.java:1541)
at
org.apache.cassandra.db.Memtable$FlushRunnable.runMayThrow(Memtable.java:336)
at
org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)
at
com.google.common.util.concurrent.MoreExecutors$SameThreadExecutorService.execute(MoreExecutors.java:297)
at
org.apache.cassandra.db.ColumnFamilyStore$Flush.run(ColumnFamilyStore.java:1154)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{noformat}
{noformat}
"RMI TCP Connection(128577)-192.168.0.1" - Thread t@282977
java.lang.Thread.State: BLOCKED
at
org.apache.cassandra.db.compaction.WrappingCompactionStrategy.getEstimatedRemainingTasks(WrappingCompactionStrategy.java:147)
- waiting to lock <31924612> (a
org.apache.cassandra.db.compaction.WrappingCompactionStrategy) owned by
"CompactionExecutor:4065" t@282454
at
org.apache.cassandra.metrics.CompactionMetrics$1.value(CompactionMetrics.java:65)
at
org.apache.cassandra.metrics.CompactionMetrics$1.value(CompactionMetrics.java:57)
at
com.yammer.metrics.reporting.JmxReporter$Gauge.getValue(JmxReporter.java:63)
at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at
com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:112)
at
com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:46)
at
com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:237)
at
com.sun.jmx.mbeanserver.PerInterface.getAttribute(PerInterface.java:83)
at
com.sun.jmx.mbeanserver.MBeanSupport.getAttribute(MBeanSupport.java:206)
at
com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:647)
at
com.sun.jmx.mbeanserver.JmxMBeanServer.getAttribute(JmxMBeanServer.java:678)
at
com.sun.jmx.remote.security.MBeanServerAccessController.getAttribute(MBeanServerAccessController.java:320)
at
javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1443)
at
javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
at
javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1307)
at java.security.AccessController.doPrivileged(Native Method)
at
javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1406)
at
javax.management.remote.rmi.RMIConnectionImpl.getAttribute(RMIConnectionImpl.java:637)
at sun.reflect.GeneratedMethodAccessor21.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:323)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at
sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
at
sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
at
sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$241(TCPTransport.java:683)
at
sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$$Lambda$1/183345253.run(Unknown
Source)
at java.security.AccessController.doPrivileged(Native Method)
at
sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{noformat}
The lock protects from concurrent access through the two synchronized methods
WrappingCompactionStrategy.getEstimatedRemainingTasks and
WrappingCompactionStrategy.getNextBackgroundTask.
The lock is not just hold for a short time but for several minutes. We think
that this combined with suboptimal values for {{memtable_flush_writers}} and
{{concurrent_compactors}} caused our nodes to exhaust their heap and die after
running incremental repair.
There also seems to be no other way to reduce the number of SSTables as a user
except than waiting for the compactions to eventually finish which looks like
it can take days.
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