Stefan Egli created OAK-5601:
--------------------------------
Summary: documentMk backgroundRead should handle missing journal
entries
Key: OAK-5601
URL: https://issues.apache.org/jira/browse/OAK-5601
Project: Jackrabbit Oak
Issue Type: Bug
Components: core
Affects Versions: 1.4.1
Reporter: Stefan Egli
Assignee: Stefan Egli
The following exception has been encountered:
{noformat}03.02.2017 02:39:08.068 *WARN* [DocumentNodeStore background read
thread (1)] org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore
Background operation failed: java.lang.IllegalStateException: M
issing external change for branch revision: b3-00000159f839b963-00000000
java.lang.IllegalStateException: Missing external change for branch revision:
b3-00000159f839b963-00000000
at
org.apache.jackrabbit.oak.plugins.document.JournalEntry$3$1.computeNext(JournalEntry.java:321)
at
org.apache.jackrabbit.oak.plugins.document.JournalEntry$3$1.computeNext(JournalEntry.java:309)
at
com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at
com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at
org.apache.jackrabbit.oak.plugins.document.JournalEntry.addTo(JournalEntry.java:287)
at
org.apache.jackrabbit.oak.plugins.document.JournalEntry.fillExternalChanges(JournalEntry.java:210)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.backgroundRead(DocumentNodeStore.java:1813)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.internalRunBackgroundReadOperations(DocumentNodeStore.java:1702)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.runBackgroundReadOperations(DocumentNodeStore.java:1687)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore$BackgroundReadOperation.execute(DocumentNodeStore.java:2633)
at
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore$NodeStoreTask.run(DocumentNodeStore.java:2592)
at java.lang.Thread.run(Thread.java:745)
{noformat}
That revision b3-00000159f839b963-00000000 corresponds to 1485928249699ns ==
2017-02-01T05:50:49+00:00, which means the revision that the backgroundRead is
trying to read here is 21 hours old.
The default journal GC maxAge is 6 hours though.
When it tries to read an old revision that is already deleted it [throws an
IllegalStateException|https://github.com/apache/jackrabbit-oak/blob/jackrabbit-oak-1.4.1/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/JournalEntry.java#L321].
That one is not caught properly, except in
[NodeStoreTask.run|https://github.com/apache/jackrabbit-oak/blob/jackrabbit-oak-1.4.1/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/DocumentNodeStore.java#L2593].
This means the backgroundRead has failed, with a warn, and will be retried 1
second later. Just that nothing has changed, the journal entry can still not be
found, so the same warning is issued.
Resulting in the situation that the backgroundRead will never recover.
That {{IllegalStateException}} should be caught [when calling
fillExternalChanges|https://github.com/apache/jackrabbit-oak/blob/jackrabbit-oak-1.4.1/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/DocumentNodeStore.java#L1814],
resulting in a fall-back to not reading from the journal but going the old
route.
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