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https://issues.apache.org/jira/browse/AMQ-5300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14343163#comment-14343163
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Artem Karpenko commented on AMQ-5300:
-------------------------------------
Since this is resolved and specifically mentiones LevelDB, I've opened another
issue for Replicated LevelDB: AMQ-5618
> Inifinite loop when attempting to replay levelDB logs to rebuild index
> ----------------------------------------------------------------------
>
> Key: AMQ-5300
> URL: https://issues.apache.org/jira/browse/AMQ-5300
> Project: ActiveMQ
> Issue Type: Bug
> Components: activemq-leveldb-store
> Affects Versions: 5.9.1, 5.10.0
> Environment: Linux
> Reporter: Vu Le
> Assignee: Gary Tully
> Fix For: 5.11.0
>
>
> While searching for a workaround for issue AMQ-5284, I came across this issue.
> To work around the serialization issue (AMQ-5284), I deleted the index
> snapshots from the LevelDB datastore. This will replay the logs to regenerate
> the index. However, if a log rotation has already occurred, you will get an
> infinite loop upon restart.
> Here are the steps to reproduce what I am seeing:
> Configure ActiveMQ 5.10.0 to use a LevelDB data store with the log size of
> about 1MB.
> {code}
> <persistenceAdapter>
> <levelDB directory="${activemq.data}/leveldb" logSize="1000000" />
> </persistenceAdapter>
> {code}
> Then I started up the broker and published 10,000 persistent messages to a
> queue, causing the log files to rotate (twice in my case). I see the
> following files in the data store folder:
> {code}
> -rw-rw-r--. 1 user users 1000071 Jul 30 11:15 0000000000000000.log
> -rw-rw-r--. 1 user users 1000009 Jul 30 11:16 00000000000f4287.log
> drwxrwxr-x. 2 user users 4096 Jul 30 11:16 00000000001e84d0.index
> -rw-rw-r--. 1 user users 1000000 Jul 30 11:17 00000000001e84d0.log
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 dirty.index
> -rw-rw-r--. 1 user users 0 Jul 30 11:11 lock
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 plist.index
> -rw-rw-r--. 1 user users 24 Jul 30 11:11 store-version.txt
> {code}
> I then consume 5,000 messages, which causes the first log to be deleted since
> it is no longer being referenced. I see the following log statements:
> {code}
> 2014-07-30 11:29:14,960 | DEBUG | Log no longer referenced: 0 |
> org.apache.activemq.leveldb.LevelDBClient | Thread-2
> 2014-07-30 11:29:14,967 | DEBUG | Deleting log at 0 |
> org.apache.activemq.leveldb.LevelDBClient | Thread-2
> {code}
> And I see the remaining files in the data store folder (notice the
> 0000000000000000.log is gone):
> {code}
> -rw-rw-r--. 1 user users 1000009 Jul 30 11:16 00000000000f4287.log
> -rw-rw-r--. 1 user users 1000011 Jul 30 11:29 00000000001e84d0.log
> drwxrwxr-x. 2 user users 4096 Jul 30 11:29 00000000002dc71b.index
> -rw-rw-r--. 1 user users 1000000 Jul 30 11:29 00000000002dc71b.log
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 dirty.index
> -rw-rw-r--. 1 user users 0 Jul 30 11:11 lock
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 plist.index
> -rw-rw-r--. 1 user users 24 Jul 30 11:11 store-version.txt
> {code}
> At this point, I shut down the broker and here is the listing of what's left
> in the data store:
> {code}
> -rw-rw-r--. 1 user users 1000009 Jul 30 11:16 00000000000f4287.log
> -rw-rw-r--. 1 user users 1000011 Jul 30 11:29 00000000001e84d0.log
> -rw-rw-r--. 1 user users 1000000 Jul 30 11:29 00000000002dc71b.log
> drwxrwxr-x. 2 user users 4096 Jul 30 11:36 0000000000301737.index
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 dirty.index
> drwxrwxr-x. 2 user users 4096 Jul 30 11:11 plist.index
> -rw-rw-r--. 1 user users 24 Jul 30 11:11 store-version.txt
> {code}
> I then delete the index folder within the data store (in my case
> "0000000000301737.index"). I am doing this to force a replay of the logs to
> regenerate the index (due to the serialization issue I ran into).
> And finally, this is the message I am getting once I start the broker back up
> (infinite loop of this same message, and I have to shut down the broker):
> {code}
> 2014-07-30 11:40:27,415 | WARN | No reader available for position: 0,
> log_infos:
> {1000071=LogInfo(/home/user/apache-activemq-5.10.0/data/leveldb/00000000000f4287.log,1000071,1000009),
>
> 2000080=LogInfo(/home/user/apache-activemq-5.10.0/data/leveldb/00000000001e84d0.log,2000080,1000011),
>
> 3000091=LogInfo(/home/user/apache-activemq-5.10.0/data/leveldb/00000000002dc71b.log,3000091,0)}
> | org.apache.activemq.leveldb.RecordLog | main
> {code}
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