[jboss-jira] [JBoss JIRA] (JGRP-2065) RoundTrip: latency is high compared to RoundTripTcp/RoundTripServer

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-2065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13239938#comment-13239938 ] 

Bela Ban commented on JGRP-2065:
--------------------------------

Investigate behavior for 1, 10 and 100 sender threads

> RoundTrip: latency is high compared to RoundTripTcp/RoundTripServer
> -------------------------------------------------------------------
>
>                 Key: JGRP-2065
>                 URL: https://issues.jboss.org/browse/JGRP-2065
>             Project: JGroups
>          Issue Type: Task
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 4.0
>
>
> {{RoundTrip}} is a simple test between 2 members measuring round-trip latency. The sender continually sends a message, the receiver receives it and sends the response, and the sender unblocks when the response is received. Then the sender sends the next message. 
> The time for the request is then logged at the sender and a min/avg/max value is computed (probably changed to histograms later).
> {{RoundTrip}} uses a JGroups channel, configured with {{-props}}, e.g. {{-props ~/tcp.xml}}.
> {{RoundTripTcp}} does the same, but uses direct TCP sockets (no JGroups) for communication.
> {{RoundTripServer}} uses the client-server classes of JGroups for communication, but no channel is used.
> Round trip times (both processes on the same box, a Mac mini):
> * {{RoundTrip}} (with {{tcp.xml}} shipped with JGroups): *110 us*
> * {{RoundTripTcp}}: *46 us*
> * {{RoundTripServer}}: *49 us*
> Note that the client/server classes used by {{RoundTripServer}} are also used by the TCP transport (configured in {{tcp.xml}}. 
> {{RoundTripServer}} is ~6% slower than {{RoundTripTcp}}, but that can be attributed to the additional work the former has to do (e.g. connection reaping etc). This is something we can focus on later.
> The big difference are the 110 us for {{RoundTrip}}. The goal is to find out what causes this and eliminate it. Since {{RoundTrip}} and {{RoundTripServer}} use the same underlying client/server classes in JGroups, let's compare these 2.
> Tasks:
> * Remove all protocols other than TCP in the running stack: (e.g. {{probe.sh remove-protocol=MFC}}). I already did this and the diff was negligible, but let's run this again
> * Try various bundlers (e.g. NoBundler)
> * Reduce threads in the threadpools, possibly disable (regular and OOB) thread pools (replace with DirectExecutor)
> * The default is 1 sender thread, but try with multiple threads
> * Measure perf between sending a message (in the bundler) and receiving it



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