Abe Ratnofsky created CASSANDRA-19427:
-----------------------------------------
Summary: Fix concurrent access of ClientWarn causing AIOBE for
SELECT WHERE IN queries with multiple coordinator-local partitions
Key: CASSANDRA-19427
URL: https://issues.apache.org/jira/browse/CASSANDRA-19427
Project: Cassandra
Issue Type: Bug
Components: Consistency/Coordination, Legacy/Local Write-Read Paths
Reporter: Abe Ratnofsky
Assignee: Abe Ratnofsky
On one of our clusters, we noticed rare but periodic
ArrayIndexOutOfBoundsExceptions:
{code:java}
message="Uncaught exception on thread Thread[ReadStage-3,5,main]"
exception="java.lang.RuntimeException: java.lang.ArrayIndexOutOfBoundsException
at
org.apache.cassandra.service.StorageProxy$DroppableRunnable.run(StorageProxy.java:2579)
at
java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at
org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$FutureTask.run(AbstractLocalAwareExecutorService.java:162)
at
org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$LocalSessionFutureTask.run(AbstractLocalAwareExecutorService.java:134)
at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:119)
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.ArrayIndexOutOfBoundsException"{code}
The error was in a Runnable, so the stacktrace didn't directly indicate where
the error was coming from. We enabled JFR to log the underlying exception that
was thrown:
{code:java}
message="Uncaught exception on thread Thread[ReadStage-2,5,main]"
exception="java.lang.RuntimeException:
java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 0
at
org.apache.cassandra.service.StorageProxy$DroppableRunnable.run(StorageProxy.java:2579)
at
java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at
org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$FutureTask.run(AbstractLocalAwareExecutorService.java:162)
at
org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$LocalSessionFutureTask.run(AbstractLocalAwareExecutorService.java:134)
at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:119)
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for
length 0
at java.base/java.util.ArrayList.add(ArrayList.java:487)
at java.base/java.util.ArrayList.add(ArrayList.java:499)
at org.apache.cassandra.service.ClientWarn$State.add(ClientWarn.java:84)
at org.apache.cassandra.service.ClientWarn$State.access$000(ClientWarn.java:77)
at org.apache.cassandra.service.ClientWarn.warn(ClientWarn.java:51)
at
org.apache.cassandra.db.ReadCommand$1MetricRecording.onClose(ReadCommand.java:596)
at
org.apache.cassandra.db.transform.BasePartitions.runOnClose(BasePartitions.java:70)
at org.apache.cassandra.db.transform.BaseIterator.close(BaseIterator.java:95)
at
org.apache.cassandra.service.StorageProxy$LocalReadRunnable.runMayThrow(StorageProxy.java:2260)
at
org.apache.cassandra.service.StorageProxy$DroppableRunnable.run(StorageProxy.java:2575)
... 6 more"{code}
An AIOBE on ArrayList.add(E) should only be possible when multiple threads
attempt to call the method at the same time.
This was seen while executing a SELECT WHERE IN query with multiple partition
keys. This exception could happen when multiple local reads are dispatched by
the coordinator in
org.apache.cassandra.service.reads.AbstractReadExecutor#makeRequests. In this
case, multiple local reads exceed the tombstone warning threshold, so multiple
tombstone warnings are added to the same ClientWarn.State reference.
Currently, org.apache.cassandra.service.ClientWarn.State#warnings is an
ArrayList, which isn't safe for concurrent modification, causing the AIOBE to
be thrown.
I have a patch available for this, and I'm preparing it now. The patch is
simple - it just changes org.apache.cassandra.service.ClientWarn.State#warnings
to a thread-safe CopyOnWriteArrayList. I also have a jvm-dtest that
demonstrates the issue but doesn't need to be merged - it shows how a SELECT
WHERE IN query with local reads that add client warnings can add to the same
ClientWarn.State from different threads. I'll push that in a separate branch
just for demonstration purposes.
This appears to have been an issue since at least 3.11, that was the earliest
release I checked.
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