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From Hiranya Jayathilaka <>
Subject HTTP Core Performance and Reactor Buffer Size
Date Thu, 21 Nov 2013 20:08:50 GMT
Hi Devs,

I just found out that the performance of the Synapse Pass Through transport is highly sensitive
to the RcvBufferSize of the IO reactors (especially when mediating very large messages). Here
are some test results. In this case, I'm simply passing through a 1M message through Synapse
to a backend server, which simply echoes it back to the client. Notice how the execution time
of the scenario varies with the RcvBufferSize of the IO reactors.

RcvBufferSize (in bytes)                  Scenario Execution Time (in seconds)
8192 (Synapse default)                    25.9
16384                                                   0.4
32768                                                   0.2

Is this behavior normal? If so does it make sense to change the Synapse default buffer size
to something larger (e.g. 16k)?

Interestingly I see this difference in behavior on Linux only. I cannot see a significant
change in behavior on Mac. 

Appreciate your thoughts on this.


Hiranya Jayathilaka
Mayhem Lab/RACE Lab;
Dept. of Computer Science, UCSB;
E-mail:;  Mobile: +1 (805) 895-7443

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