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I have been stress testing my PHP application hosted on Linux and using Apache. I am using Apache JMeter for stress test. During the test the normal response times are below 100 milliseconds. But during the test after few minutes the response times go high for the same HTTP requests than it comes down and after few minutes it again goes high. As high as 60K milliseconds.

I am a newbie in PHP and Apache. I am not sure from where to start look for the problem. Can anyone direct me on to how can I troubleshoot for this issue? The application is hosted on Amazon EC2.

First thing I am thinking about is may be garbage collection is the issue. Am I right?

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up vote 1 down vote accepted

If response times go as high as 60 seconds, you may be looking at a gross instance-wide problem. Run atop on the EC2 instance while you're running your jmeter test, and watch for problems such as memory exhaustion and high disk I/O.

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