[openjms-developer] [ openjms-Bugs-1192265 ] Message lost in multi-processor environment

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Bugs item #1192265, was opened at 2005-04-29 18:22
Message generated for change (Comment added) made by tanderson
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Category: server
Group: v0.7.6.1

Status: Closed
Resolution: Fixed

Priority: 7
Submitted By: shyan (shyan)
Assigned to: Tim Anderson (tanderson)

Summary: Message lost in multi-processor environment

Initial Comment:
I found message lost sometime in multi-processor
envirement.
I test and simulate this situation and get the following
result.

Sometime messages get the same sequenceNumber.

so message handle have same sequenceNumber in
PMDVector and persistent storage(DB).
When cunsumer receive message,the message handle
removed from PMDVector.

Because MessageHandleComparator only compare
three attributes
(priority,acceptedtime,sequencedNumber) ,so if the
three attributes equal,the handle is equal.

Two elements(or more) is removed from PMDVector.

So some messages lost,but thoses message still exists
in database.

You can send two messages to server,and shutdown
server.
Then modify two record's acceptedtime and
sequenceedNumber to same value.
Start server and receive all message,you can only get
one message,and the lost message is still exist in db.

I have a solution to fix this problem.
Add messageid conditition in
MessageHandleComparator.compare method to avoid
compare confuse,because messageid is always unique.

The attache file is my patch.

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Comment By: Tim Anderson (tanderson)

Date: 2005-10-11 00:15

Message:
Logged In: YES
user_id=557161

Fixed in CVS. Fix will be available in 0.7.7-alpha-2

----------------------------------------------------------------------

Comment By: Tim Anderson (tanderson)
Date: 2005-10-11 00:07

Message:
Logged In: YES
user_id=557161

Good catch, but a better solution is to synchronize the sequence
no. generation in MessageMgr.java. Two messages should never
be assigned identical sequence numbers.

Also note that the object database is no longer supported in 0.7.7

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