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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 20:50:25 GMT
On Wed, Feb 17, 2010 at 2:26 PM, Robert Hall <rfhall@berkeley.edu> wrote:
>
> On Feb 17, 2010, at 12:06 PM, Dan Denton wrote:
>
>> 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
>>>
>>
>> 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.
>>
>
> Dan, this sounds like an Apache httpd configuration issue.
>
> Check the values for the 'KeepAliveTimeout' and 'KeepAlive' directives,
> http://httpd.apache.org/docs/2.0/mod/core.html#keepalive
>
> I suggest using "KeepAlive  On" and "KeepAliveTimeout 1"; the latter is
> probably defaulted to 15.
>
> - Robert
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>
Thanks again Robert. My apache proxy has both directives already set,
and KeepAliveTimeout was indeed set to 15. I tried running the 400
session test across 4 slaves with KeepAliveTimout set to 1 and 30, and
the same result. A failure rate of approximately 20 percent.

Are there any other directives you suggest changing?

Thanks...

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