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From Dan Denton <random.da...@gmail.com>
Subject Re: [users@httpd] JMeter Load Testing of Tomcat through Apache Proxy
Date Wed, 17 Feb 2010 20:06:36 GMT
On Mon, Feb 15, 2010 at 12:53 PM, Robert Hall <rfhall@berkeley.edu> wrote:
> Dan,
>
> On Feb 15, 2010, at 10:37 AM, Dan Denton wrote:
>
>> Hello all. I’m trying to load test a login page served by tomcat 6,
>> proxied through apache 2 with mod_proxy. I’m using JMeter 2.3.4 to
>> conduct the testing. My thread group consists of 500 sessions , and
>> the sample is a GET of a simple login page.
>>
>> JMeter returns errors for a varying percentage of the samples. The
>> errors returned are generally the following:
>>
>> at
>> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1037)
>> at
>> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1023)
>> at
>> org.apache.jmeter.threads.JMeterThread.process_sampler(JMeterThread.java:346)
>> at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:243)
>> at java.lang.Thread.run(Unknown Source)
>>
>> The issues I’m having are twofold. I’m having difficulty determining
>> if these errors are coming from JMeter or Tomcat, as they’re displayed
>> in the response window of JMeter. The developers think the error is
>> coming from JMeter given the last few lines of the trace above.
>
> The developers are correct.
>
>> Given that I'm not a programmer I should probably take their word for it,
>> but why would JMeter show this error as the response?
>
> The system you are running JMeter on isn't able to handle the load.
>
>> Second, I've tried tweaking my process counts (startservers, maxspare,
>> etc...) with no change in the outcome. I can mitigate the issue by
>> pointing JMeter directly to tomcat, but I need this product to go
>> through our apache proxy for SSL.
>>
>> Any help on this would be greatly appreciated.
>
> There must be some JMeter setting that will work otherwise you would be
> unable
> to access the webapp over SSL from the system that is hosting JMeter.
>
> Try reducing everything to a count of 1 in JMeter.
>
> If that doesn't work, there is a problem with the SSL config in JMeter;
> google "jmeter ssl".
>
> Otherwise, try spreading the load our across several JMeter instances
> installed on separate systems.
>
> - Robert
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>

Thanks for the reply Robert. I've set up JMeter 4 slaves, each with at
least two 2.8 Ghz procs and 2 GB of RAM, and still regardless of
whether it's 1 node simulating 400 sessions or 4 nodes each simulating
100, I still see these errors at 400 sessions or more. Also, when I
use multiple slaves to execute the test, the percentage of failures
when simulating 400 sessions is greater and the failures happen
earlier in the test.

This makes me think that this isn't just an issue with the systems
running JMeter, but I'm not sure. I've tried tweaking my SSL Session
Timeout as well, but with no effect. I did this because watching the
mod_status page on this apache instance, I can see the current session
count top out at about 330 every time, then subside. My guess was that
SSL sessions were somehow bottlenecking.

If anyone has any other suggestions, they would be greatly appreciated.

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