Java Memory Usage

The Maximum Java Heap Size (Xmx) is the maximum amount of memory that Java application can uses. A lower Xmx value will cause a decrease in performance due to JVM has to force frequent garbage collections in order to free up space, also if the Xmx value is lower than the amount of live data, it might trigger OutOfMemoryError. Customers can configure Xmx via JVM options -Xmx to optimize their Java application performance, but quite a lot of Java users never explicitly specify the -Xmx option, so in those cases the default Xmx has been used. The default values for Xmx is based on the physical memory of the machine.

Deafult Memory Usage

From Java 11 the Xmx value is 25% of the available memory with a maximum of 25 GB. However, where there is 2 GB or less of physical memory, the value set is 50% of available memory with a minimum value of 16 MB and a maximum value of 512 MB.

Customized Memory Usage

Use these java command-line parameters to control the RAM use of application:

• Use -Xmx to specify the maximum heap size
• Use -Xms to specify the initial Java heap size
• Use -Xss to set the Java thread stack size