[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - Re: Sweet life on the journal...

[clebert.suconic@jboss.com]

I was dealing with one of the most obscure bugs I had ever seen on my 20 years programming.  After I found it, as aways it was a dumb and obvious bug, but it was a little hard to find this one:

When the journal was creating a byte buffer, it was sending it to the JNI layer and it was immediately releasing the reference to the ByteBuffer. As the write was being done asynchronously, the ByteBuffer could be eventually released (GC) at the same time it was being written, what was creating gargabe on the journal.

Well.. at least that was a good exercise during my tests, so I'm pretty sure the journal is loading data properly and dealing with holes on transactions. I have written a few Stress Tests to catch this bug. I can't reproduce this on a Unit Test.

I will write a few more tests on Reload and incomplete transactions, and maybe make few other improvements on the journal. (Maybe improve the collections on the journal making it use less memory. I have a few ideas that I will input on the forums tomorrow).

BTW: Most of the information is on the WIKI already. I have made a few modifications on the code regarding Transactions counter to deal with holes and I will put that on the WIKI tomorrow. (I'm writing the counter per journal file, as reclaiming could legally get part of a transaction).

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