Ignace Desimpel created CASSANDRA-14164:
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Summary: Calling StorageService.loadNewSSTables function results
in deadlock with compaction background task
Key: CASSANDRA-14164
URL: https://issues.apache.org/jira/browse/CASSANDRA-14164
Project: Cassandra
Issue Type: Bug
Components: Compaction, Tools
Environment: code
Reporter: Ignace Desimpel
Priority: Blocker
Fix For: 2.2.x, 3.0.x
Attachments: Stack1.txt
Tested on version 2.2.11 (but seems like trunck 3.x is still the same for the
related code path), using nodetool refresh for restoring a snapshot
Calling StorageService.loadNewSSTables function results in deadlock with
compaction background task.
because :
>From StorageService class , function public void loadNewSSTables(String
>ksName, String cfName) a call is made to ColumnFamilyStore class , function
>public static synchronized void loadNewSSTables(String ksName, String cfName)
>and then a call to Keyspace class, function public static Keyspace open(String
>keyspaceName)
getting to the function private static Keyspace open(String keyspaceName,
Schema schema, boolean loadSSTables)
finally trying to get a lock by synchronized (Keyspace.class)
So inside the ColumnFamilyStore class lock, there is an attempt to get the lock
on the Keyspace.class
Now at the same time I have the thread OptionalTasks executing the
ColumnFamilyStore.getBackgroundCompactionTaskSubmitter() task.
The thread task is also calling Keyspace.open function, already progressed as
far as getting the lock on Keyspace class.
But then the call also initializes the column families and thus is calling on
class ColumnFamilyStore the public static synchronized ColumnFamilyStore
createColumnFamilyStore ...
Result : the external call on loadNewSSTables blocks the internal compaction
background task.
So function 1 locks A and then B
And function 2 locks B and then A
leading to deadlock (due to incorrect order of locking objects)
Regards,
Ignace
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