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From Tuukka Mustonen <>
Subject High CPU utilization in JMeter 3.x with HttpClient 4 leads to freeze
Date Wed, 01 Feb 2017 07:21:01 GMT

After upgrading to JMeter 3.0 or 3.1 I experience high CPU usage that
renders JMeter unusable. CPU usage ramps quickly up and after having
~100-200 concurrent users or so (in ~30 seconds), it hits 100% on my
i7-4600. Shortly after, whole JMeter freezes and I have to kill it.

On 2.13 everything goes smoothly (with default settings). CPU usage stays
at ~30% even with 500 users.

The experience is similar on both Windows 10 and Linux (Ubuntu 14.04 LTS
guest in Virtualbox).

The problems I saw in JMeter 3:

- Permission denied: connect
- After a while it runs out of heap space

For "Permission denied: connect" I tried to set
(in a few places to make sure it would really be in use) and tried to run
JMeter as administrator (in Win). No effect.

I also tried increasing heap size, but that didn't help either. And I think
memory size is not the root cause here - rather the result.

I am normally connected to VPN but I also tried disabling it. No effect.

I tried disabling with and without IPv6 enabled in Windows network
connection settings. No effect.

I am running a few extra JMeter plugins. Tried cutting my test scenario to
minimum. No effect.

I am running anti-virus software that I cannot disable, due to this being
forced by IT department. However, it's not a problem with 2.13 so I assume
it shouldn't be a problem here either.

FINALLY, once I set HTTP request implementation from Apache HttpClient 4 to
HttpClient 3.1 or JAVA, the problem vanishes - CPU stays where it did with
JMeter 2.13.

I'm running Oracle JVM 8 (update 121 on Win, update 111 on Linux).

Why does (the recommended) HttpClient 4 cause problems here? Is this a know
bug/issue? JMeter 3.x is running newer version compared to 2.13, but what
change in HttpClient 4 might cause the problems described?

Any ideas?


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