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IDEA/Maven Troubleshooting

Idea Performance

If your Idea isn’t running smoothly or becomes unresponsive when you open multiple projects, try increasing memory like this:

Help → Edit Custom VM Options… and then set max. memory higher (-Xmx…). Don’t forget to restart Idea

Failing Maven Import in Idea

Check Log File

Help → Show log in … and then open idea.log.

Increase Memory

It happens frequently that Maven projects are marked red in IDEA after a Maven import and you have to retry the import multiple times. This often happen because there isn’t enough memory.

Instructions:

Go to File → Settings → Build, Execution, Deployment → Buid Tools → Maven → Importing → VM options for Importer and set -Xmx… higher.

Decrease Number of Parallel Jobs

If you physically don’t have enough memory. Consider reducing the number of jobs per CPU.

Instructions:

File → Settings → Build, Execution, Deployment → Buid Tools → Maven → Importing → Thread.

(default 1.5C = 1.5 jobs per CPU)

Failing mvn install

Out of Physical Memory

If the build keeps failing randomly, often because of failures in Gulp or NPM 1. In particular, if you see anything about exit code 137 2. Then, it’s probably because you ran out-of-memory. Check dmesg (Linux) for any message about out of memory. (If there is a large table listing memory usage per process it’s an OOM.)

Consider reducing the number of jobs per CPU to reduce memory usage (e.g. by using -T1C).

Exceeding the Alloted Memory

If you see OutOfMemoryErrors during the build, it’s often because too little memory is allotted to Maven. Consider increasing the memory limit by setting the environment variable MAVEN_OPTS.

For instance, by adding this in your ~/.profile (and restarting the terminal):

export MAVEN_OPTS="-Xmx1024m"

Alternatively, you can decrease the memory usage by decreasing the number of jobs as described in the previous section.

“Too many open files” During Maven Build

With the introduction of Java 11, far more files are opened at once during mvn build sometimes leading to the error “Too many open files”. Increase the the max. number of open files in such a case.

Increasing the limit on Linux:

Create /etc/security/limits.d/open_file_limit.conf with this content:

*                -       nofile          1000000

Log out and in again for this to become effective. Use ulimit -n to show the current limit.

Hint

Should you have trouble increasing the limit, you can try decreasing the number of parallel jobs running during the build using the -T flag. For instance, specify -T3 to run three jobs or specify -T0.5C to run 0.5 jobs per CPU core.

Footnotes

1

Because the out-of-memory killer on Linux sacrifices children first. Hence Gulp and NPM tend to be killed first. Other OSes behave differently and thus symptoms may differ (e.g. you may see memory allocation errors instead).

2

Exit statuses higher than 128 are usually 128 + SIGNAL_NUMBER (see kill -l). In this case 128 + 9 (SIGKILL) = 137.