Increase Max Connections under Ubuntu? (Tsung concurrency test)

Question

I am testing NodeJs, especially the concurrency. I am using Tsung for this. Unfortunately Tsung seems not be able to spawn enough users. I'm only getting about 30K simultaneous connections although ~2GB RAM is still unused. (Check the charts)

The XML-Config File is the following:

<tsung loglevel="notice" version="1.0">
<!-- Client side setup -->
−
<clients>
<client host="localhost" use_controller_vm="false"/>
<client host="localhost" use_controller_vm="false"/>
</clients>
<!-- Server side setup -->
−
<servers>
<server host="localhost" port="8000" type="tcp"/>
</servers>
−
<!--
 to start os monitoring (cpu, network, memory). Use an erlang
  agent on the remote machine or SNMP. erlang is the default 
-->
−
<monitoring>
<monitor host="localhost" type="erlang"/>
</monitoring>
−
<load>
−    
<arrivalphase phase="1" duration="50" unit="minute">
<users interarrival="0.000000001" unit="second"/>
</arrivalphase>
</load>
−
<sessions>
−
<session name="nodeJS" probability="100" type="ts_http">
−
<for from="0" to="40" incr="1" var="counter">
−
<request>
<http url="http://localhost:8000/" version="1.1" method="GET"/>
</request>
<thinktime random="false" value="300"/>
</for>
</session>
</sessions>
</tsung>

So how to increase the users, so that all the RAM is used???

Fagin

Answer 1

I solved the problem!!! I just needed to increase the Port Range. With 4GB RAM i reach nearly the max possible Port Range. Exactly 61980 simultaneous connections. Great NodeJs!

Teddie

Any additional tips on making this happen? Do you end up using most of the RAM? What's the setup - I know there are issues on node only supporting 1GB RAM. – Candytuft

Answer 2

Depending on your CPU architecture, node might only support 1GB of RAM: http://code.google.com/p/v8/issues/detail?id=847

To work around this you can run multiple instances of node (and have them talk to each other if needed). Libraries like multi-node can help with this: https://github.com/kriszyp/multi-node

Otherwise you need to look into tuning your server for lots of long running connections - outside my expertise but there are lots of people thinking about this. Here's a thread from the nodejs Google Group about supporting 100k connections: https://groups.google.com/d/topic/nodejs/0Z34PH_R88o/discussion

Sunward