Marcel Reutegger created OAK-4697:
-------------------------------------
Summary: Optimize read of old node state
Key: OAK-4697
URL: https://issues.apache.org/jira/browse/OAK-4697
Project: Jackrabbit Oak
Issue Type: Improvement
Components: core, documentmk
Reporter: Marcel Reutegger
Assignee: Marcel Reutegger
Fix For: 1.6
Reading a node state with an old revision from a document can be expensive when
many changes happened on a property in the meantime.
A typical stack trace looks like this:
{noformat}
at
org.apache.jackrabbit.oak.plugins.document.NodeDocument.getPreviousDocument(NodeDocument.java:1337)
at
org.apache.jackrabbit.oak.plugins.document.PropertyHistory$1.apply(PropertyHistory.java:70)
at
org.apache.jackrabbit.oak.plugins.document.PropertyHistory$1.apply(PropertyHistory.java:63)
at com.google.common.collect.Iterators$8.transform(Iterators.java:794)
at
com.google.common.collect.TransformedIterator.next(TransformedIterator.java:48)
at com.google.common.collect.Iterators$7.computeNext(Iterators.java:646)
at
com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at
com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at
com.google.common.collect.Iterators$PeekingImpl.hasNext(Iterators.java:1139)
at
org.apache.jackrabbit.oak.plugins.document.PropertyHistory$2.refillQueue(PropertyHistory.java:121)
at
org.apache.jackrabbit.oak.plugins.document.PropertyHistory$2.computeNext(PropertyHistory.java:96)
at
org.apache.jackrabbit.oak.plugins.document.PropertyHistory$2.computeNext(PropertyHistory.java:88)
at
com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at
com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at
org.apache.jackrabbit.oak.plugins.document.ValueMap$1$3.nextIterator(ValueMap.java:105)
at
org.apache.jackrabbit.oak.plugins.document.util.MergeSortedIterators.fetchNextIterator(MergeSortedIterators.java:98)
at
org.apache.jackrabbit.oak.plugins.document.util.MergeSortedIterators.next(MergeSortedIterators.java:85)
at
com.google.common.collect.Iterators$PeekingImpl.peek(Iterators.java:1162)
at
org.apache.jackrabbit.oak.plugins.document.util.MergeSortedIterators.adjustFirst(MergeSortedIterators.java:117)
at
org.apache.jackrabbit.oak.plugins.document.util.MergeSortedIterators.next(MergeSortedIterators.java:78)
at
org.apache.jackrabbit.oak.plugins.document.NodeDocument.getLatestValue(NodeDocument.java:1972)
at
org.apache.jackrabbit.oak.plugins.document.NodeDocument.getNodeAtRevision(NodeDocument.java:990)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.readNode(DocumentNodeStore.java:1079)
{noformat}
The read operation goes through the property history until it finds the most
recent change. The old the read revision, the more changes are scanned.
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