Alan Protasio created AMQ-7143:
----------------------------------
Summary: Temporary transaction file (PageFile) being opened and
closed many times, leading poor performance
Key: AMQ-7143
URL: https://issues.apache.org/jira/browse/AMQ-7143
Project: ActiveMQ
Issue Type: Improvement
Components: KahaDB
Affects Versions: 5.15.8
Reporter: Alan Protasio
Hi,
This is just an optimization when we have a transaction with many writes
(bigger than 10mb by default) and we create a temporary file.
The problem is when this transaction is committed, this temporary file is
opened and closed many times (number of writes inside the transaction), causing
poor performance (this is operation "freezes the world" during the checkpoint).
See:
[https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/page/PageFile.java#L1147]
[https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/page/PageFile.java#L203]
Note that is the recoveryFile is enabled, we open and close the temporary 3
times for each index write.
There is also a small bug that if the transaction is rolledBack, the temporary
file is left there forever, see:
[https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/page/Transaction.java#L686]
[https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/page/PageFile.java#L1200]
As the transaction is rolledback, no writes will be performed and so, the file
will never be deleted.
The proposed change, use the same "RandomAccessFile" object used in the
transaction and close if when all writes is done (so we stop opening and
closing it for each write, and only do it one time per transaction).
Thanks
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
