JMeter runs out of memory while trying to generate HTML report

Question

I need help, maybe someone had similar problem with JMeter report generation

I have JMeter script with SOAP API requests, which are placing a purchasing order. There are no issues during order creation time, but when all requests are finished and JMeter is trying to generate report I am getting an error:

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid8676.hprof ...
Heap dump file created [7011161840 bytes in 93.212 secs]
Uncaught Exception java.lang.OutOfMemoryError: Java heap space in thread Thread[StandardJMeterEngine,5,main]. See log file for details.

I used JConsole to monitor JMeter during execution and noticed that heap mostly was at 25% during test run and went up to 100% during report generation. Thanks in advance

Answer 1

The error clearly states that JMeter lacks Java Heap space in order to complete the report generation operation, it might be the case you executed a long-running test and your .jtl results file is very big so it doesn't fit into 7GB of heap. It normally indicates that a developer is not too familiar with memory management and cannot come up with a better solution than load everything into memory in one shot instead of doing it in batches/buffers so it might be a good idea to raise an issue in JMeter's Bugzilla

So just increase JVM heap size allocated to JMeter by manipulating -Xmx parameter, even if your system will start intensively using the swap file I believe you should be able to live with this.

Alternative option is generating tables/charts using JMeter Plugins Command Line Graph Plotting Tool , however this way you will get individual results rather than the fancy HTML dashboard

Answer 2

I've hit this issue numerous times when the results file from a test is very large. What you need to do is set the max heap size before generating the Dashboard report. What value you can set the max heap size depends on whether you're running on a 32-bit OS versus a 64-bit and how much RAM is available on the machine/VM. If the machine you're generating the report on doesn't have enough RAM available, then you can copy the results file to another machine which has more. For example, when I hit this issue on a test VM, I normally just copy the results file locally to my laptop which has 16GB and run the following command:

JVM_ARGS="-Xms3072m -Xmx12g" && export JVM_ARGS && jmeter -g resultsFile.jtl -o outputReport