Gary Helmling created HBASE-16788:
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Summary: Race in compacted file deletion between HStore close()
and closeAndArchiveCompactedFiles()
Key: HBASE-16788
URL: https://issues.apache.org/jira/browse/HBASE-16788
Project: HBase
Issue Type: Bug
Components: regionserver
Affects Versions: 1.3.0
Reporter: Gary Helmling
Assignee: Gary Helmling
Priority: Blocker
HBASE-13082 changed the way that compacted files are archived from being done
inline on compaction completion to an async cleanup by the
CompactedHFilesDischarger chore. It looks like the changes to HStore to
support this introduced a race condition in the compacted HFile archiving.
In the following sequence, we can wind up with two separate threads trying to
archive the same HFiles, causing a regionserver abort:
# compaction completes normally and the compacted files are added to
{{compactedfiles}} in HStore's DefaultStoreFileManager
# *threadA*: CompactedHFilesDischargeHandler runs in a RS executor service,
calling closeAndArchiveCompactedFiles()
## obtains HStore readlock
## gets a copy of compactedfiles
## releases readlock
# *threadB*: calls HStore.close() as part of region close
## obtains HStore writelock
## calls DefaultStoreFileManager.clearCompactedfiles(), getting a copy of same
compactedfiles
# *threadA*: calls HStore.removeCompactedfiles(compactedfiles)
## archives files in {compactedfiles} in HRegionFileSystem.removeStoreFiles()
## call HStore.clearCompactedFiles()
## waits on write lock
# *threadB*: continues with close()
## calls removeCompactedfiles(compactedfiles)
## calls HRegionFIleSystem.removeStoreFiles() ->
HFileArchiver.archiveStoreFiles()
## receives FileNotFoundException because the files have already been archived
by threadA
## throws IOException
# RS aborts
I think the combination of fetching the compactedfiles list and removing the
files needs to be covered by locking. Options I see are:
* Modify HStore.closeAndArchiveCompactedFiles(): use writelock instead of
readlock and move the call to removeCompactedfiles() inside the lock. This
means the read operations will be blocked while the files are being archived,
which is bad.
* Synchronize closeAndArchiveCompactedFiles() and modify close() to call it
instead of calling removeCompactedfiles() directly
* Add a separate lock for compacted files removal and use in
closeAndArchiveCompactedFiles() and close()
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