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Marcel Reutegger commented on JCR-1213: --------------------------------------- Because getDocumentNumber() may be called from multiple concurrent threads. If the block is not synchronized, there is no guarantee that the docNumber and the reader are consistent. A JVM may update the docNumber and the reader out-of-order if the code is not synchronized. Likewise if no synchronization is present the JVM may operate on local memory that e.g. represents a stale docNumber. > UUIDDocId cache does not work properly because of weakReferences in > combination with new instance for combined indexreader > --------------------------------------------------------------------------------------------------------------------------- > > Key: JCR-1213 > URL: https://issues.apache.org/jira/browse/JCR-1213 > Project: Jackrabbit > Issue Type: Improvement > Components: query > Affects Versions: 1.3.3 > Reporter: Ard Schrijvers > Fix For: 1.4 > > > Queries that use ChildAxisQuery or DescendantSelfAxisQuery make use of > getParent() functions to know wether the parents are correct and if the > result is allowed. The getParent() is called recursively for every hit, and > can become very expensive. Hence, in DocId.UUIDDocId, the parents are cached. > Currently, docId.UUIDDocId's are cached by having a WeakRefence to the > CombinedIndexReader, but, this CombinedIndexReader is recreated all the time, > implying that a gc() is allowed to remove the 'expensive' cache. > A much better solution is to not have a weakReference to the > CombinedIndexReader, but to a reference of each indexreader segment. This > means, that in getParent(int n) in SearchIndex the return > return id.getDocumentNumber(this) needs to be replaced by return > id.getDocumentNumber(subReaders[i]); and something similar in > CachingMultiReader. > That is all. Obviously, when a node/property is added/removed/changed, some > parts of the cached DocId.UUIDDocId will be invalid, but mainly small indexes > are updated frequently, which obviously are less expensive to recompute. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.