While I have never looked at this particular application (Synapse), when
faced with this kind of issue (peculiar things happening under load), I
usually find that it is thread-safety related.  They can be the devil to
find, though your excellent effort should certainly point folks in the right
direction.

JRJ

-----Original Message-----
From: Gregory Van seghbroeck
[mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 06, 2007 3:47 AM
To: [email protected]
Subject: Synapse looses messages under high load


Dear All,

We have configured and extended synapse to work as a simple message 
forwarder. The incoming messages get forwarded in a round-robin way to 2 
external Tomcat-axis2 servers.
This works extremely well with a few messages (even if we use several 
simultaneous clients). But when we stress test our setup, we notice 
something peculiar. We have sent in a particular test run 1110 requests 
to synapse, but at the client we only got 878 responses back. Via 
monitoring and logging we noticed that our Tomcat-Axis2 servers  handled 
all the  incoming messages correctly, but somewhere between receiving 
the response in synapse and sending it to the clients 232 messages were 
lost.
Some more monitoring and logging showed us that the Synapse server 
machine receives all responses back from our Tomcat-Axis2 servers (this 
was done via a network sniffer). So something internally in Synapse 
causes the lost messages.
The debug-logs on the org.apache.axis2.transport classes showed a 
discrepancy between the content encoder (/[DEBUG] 06 nov 10:51:27.828 AM 
I/O reactor worker thread 2 
[org.apache.axis2.transport.nhttp.ClientHandler]HTTP connection 
[/157.193.215.56:9090]: Content encoder [chunk-coded; completed: true]/) 
en content decoder (/BUG] 06 nov 10:51:28.718 AM I/O reactor worker 
thread 2 [org.apache.axis2.transport.nhttp.ClientHandler]HTTP connection 
[/157.193.215.56:9090]: Content decoder [chunk-coded; completed: true]/) 
for both Tomcat-axis2 servers. We noticed 1110 of the content encoder 
entries and only 878 entries for the content decoder. These numbers fit 
to perfectly to be coincidence.

Is there anybody on this mailing-list that has an idee what may cause 
this problem and how to resolve it?

Many thanks,
Gregory


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