Dear Jackrabbit Oak developers,
we are currently trying to hunt down a performance issue we are facing
at a customer site.
We strongly need your help on this so any comments would be greatly
appreciated.
We have a MongoDB as a backend of a Oak repository where we see hundreds
of expensive queries being executed during a rather simple operation.
It happens when we are saving a session in which we added a child node
to a node already containing a very large number of children.
This has not been the case with Jackrabbit Oak 1.4.8 and 1.4.26 but it
is an issue with 1.10.8 and 1.22.3.
Newer versions have not been tested yet but looking at the source we
believe that they will show that performance issue too.
What we know so far:
* The queries against the /MongoDocumentStore /are triggered via
/AbstractNodeState.equals/ (see stacktrace below)
* A TODO "inefficient unless there are very few child nodes" in that
method indicates poor performance but this has been there since a long
time and cannot explain the issue
* OAK-7401 introduced the class /ModifiedDocumentNodeState /class which
is not inheriting /ModifiedNodeState /or /AbstractDocumentNodeState
/(see class inheritance diagram)
*/AbstractDocumentNodeState#equals/ is checking against instances of
/ModifiedNodeState /and /AbstractDocumentNodeState /but not
/ModifiedDocumentNodeState/.
* /AbstractDocumentNodeState#equals/ triggers the "slow"
/AbstractNodeState#equals/ as a last resort
We definitely do not see the full picture yet but guessing from a
high-level perspective it looks like the introduction of
/ModifiedDocumentNodeState /broke the equals logic in class
/AbstractDocumentNodeState/.
Would you agree with that conclusion?
Is there anything further I can provide?
_/Stacktrace:/_
MongoDocumentStore.query(Collection<T>, String, String, String, long,
int) line: 609
MongoDocumentStore.query(Collection<T>, String, String, int) line: 598
DocumentNodeStore.readChildDocs(String, String, int) line: 1293
DocumentNodeStore.readChildren(AbstractDocumentNodeState, String, int)
line: 1233
DocumentNodeStore$7.call() line: 1185
DocumentNodeStore$7.call() line: 1182
LocalCache$LocalManualCache$1.load(Object) line: 4724
LocalCache$LoadingValueReference<K,V>.loadFuture(K, CacheLoader<? super
K,V>) line: 3522
LocalCache$Segment<K,V>.loadSync(K, int, LoadingValueReference<K,V>,
CacheLoader<? super K,V>) line: 2315
LocalCache$Segment<K,V>.lockedGetOrLoad(K, int, CacheLoader<? super
K,V>) line: 2278
LocalCache$Segment<K,V>.get(K, int, CacheLoader<? super K,V>) line: 2193
LocalCache<K,V>.get(K, CacheLoader<? super K,V>) line: 3932
LocalCache$LocalManualCache<K,V>.get(K, Callable<? extends V>) line: 4721
DocumentNodeStore.getChildren(AbstractDocumentNodeState, String, int)
line: 1182
DocumentNodeState.getChildNodeCount(long) line: 293
AbstractNodeState.equals(NodeState, NodeState) line: 375
DocumentNodeState(AbstractDocumentNodeState).equals(Object) line: 91
AbstractNodeState.equals(NodeState, NodeState) line: 384
DocumentNodeState(AbstractDocumentNodeState).equals(Object) line: 91
DocumentNodeStoreBranch$InMemory.setRoot(NodeState) line: 481
DocumentNodeStoreBranch.setRoot(NodeState) line: 111
DocumentRootBuilder.purge() line: 185
DocumentRootBuilder.merge(CommitHook, CommitInfo) line: 163
DocumentNodeStore.merge(NodeBuilder, CommitHook, CommitInfo) line: 1869
MutableRoot.commit(Map<String,Object>) line: 250
RepositoryImpl$1(SessionDelegate).commit(Root, String) line: 346
RepositoryImpl$1(SessionDelegate).save(String) line: 493
SessionImpl$8.performVoid() line: 424
RepositoryImpl$1(SessionDelegate).performVoid(SessionOperation<Void>)
line: 273
SessionImpl.save() line: 421
_/Class inheritance diagram:/_
Many thanks in advance for your help.
Best regards,
Alexander Lüders
--
Alexander Lüders, Entimo AG
Senior Software Engineer
Stralauer Platz 33-34 | 10243 Berlin | Germany
Tel +49(0)30 520 024 131
Fax +49(0)30 520 024 101
mailto:[email protected] |http://www.entimo.com
Vorstand: Marc Jantke (Vors.), Sven Prasse
Aufsichtratsvorsitzende: Erika Tannenbaum
Sitz der Gesellschaft: Berlin, Germany | Handelsregister: HRB
Berlin-Charlottenburg 85073
