Speed up Java on your desktop Linux

Even though you may have substantial amount of RAM and SSD any Java based IDE will still feel sluggish under Linux. There is a reasonably simple way of dealing with this issue — place the JDK onto ram-disk.

Ubuntu 16.04 or more recent

Ubuntu 14.o4+ alredy contains fully usable ramdisk located at /dev/shm/. The idea here would be to copy the JDK from it’s disk location onto /dev/shm/ whenever system starts since whatever was stored there goes away after shutdown.

Since we have systemd let’s utilize it to make things easier:

In some text editor create this content:

[Unit]
Description=JDK to RAMDISK
Requires=local-fs.target
After=local-fs.target

[Service]
Type=oneshot
ExecStart=/bin/cp -ru /usr/lib/jvm/java-8-openjdk-amd64/ /dev/shm/

[Install]
WantedBy=multi-user.target

Replace the path to JDK if it is different (and most likely it is) and save the file as jdk-ramdisk.service.

Now install the newly created oneshot service:

sudo cp -uv /path/to/jdk-ramdisk.service /lib/systemd/system/

sudo systemctl daemon-reload

sudo systemctl enable jdk-ramdisk.service

If you want to configure this JDK as default do this:

echo ‘export JAVA_HOME=/dev/shm/path/to/jdk’ | sudo tee -a /etc/environment

If it is for specific IDE like PHPStorm this will also do:

echo ‘export PHPSTORM_JDK=/dev/shm/path/to/jdk’ >> ~/.profile

Restart the machine and enjoy the speedup