Error in logs when ramp up period and/or number of threads is large

2
votes

I am doing a performance test using JMeter and I have the following configuration:

Threads: 100 Loop Count:1

If my Ramp-Up period is 100, not all users are being logged in (the test script involves logging in and doing a transaction); that is, only 91 threads are successfully logged in. Also, error messages are being printed out in the logs such as NullPointerException. But if my Ramp-Up period is 500, all of them are successfully logged in. I'm just confused. What is the reason behind this?

1
javajmeterperformance-testing

1 Answers

2
votes

Maybe an issue with Java Heap Space. check in jmeter.log file for OutOfMemoryError, which tells that JMeter does not have sufficient memory to perform its tasks.

Increase it, so that JMeter can accumulate more threads. (when you give more ramp-up time, number of threads running will be lower, so JMeter may not have any issue with dealing those threads.)

in jmeter.bat file:

default values:

set HEAP=-Xms512m -Xmx512m

increase heap space (to 1 GB or more based on available memory):

set HEAP=-Xms512m -Xmx1024m

Restart the JMeter and conduct the test.

if still, the issue persists, then It might be the reason that the server can not handle more than x number of parallel clients/threads at the same time, which is called the breaking point of the system.

Possible Reasons:

  1. Improper configuration of the server (minThreads, connectTimeOut etc.)
  2. lack of resources (CPU, Memory, Disk, Network etc). monitor server during the load test for these resources. Nmon tool for Unis based server & PerfMon for Windows based servers.

Possible Solutions:

  1. Tweak the server configuration to match your needs.
  2. Scale in or scale out to add additional resources.