JVM Z (GC)

2024-07-03

Enabling Z Garbage Collector (ZGC) in JVM

The Z Garbage Collector (ZGC) is a low-latency garbage collector introduced in JDK 11. It aims to minimize pause times regardless of heap size, making it suitable for large memory applications.

Steps to Enable Z Garbage Collector

  1. JVM Version: ZGC is available starting from JDK 11. Ensure you are using at least this version.

  2. Command-Line Option: To enable ZGC, use the -XX:+UseZGC option. Start your Java application with the following command:

    java -XX:+UseZGC -jar your-application.jar

  3. Heap Size Specifications: Similar to G1, you may wish to specify the initial and maximum heap sizes using -Xms and -Xmx. Example:

    java -Xms512m -Xmx8g -XX:+UseZGC -jar your-application.jar

  4. Tuning Parameters: ZGC has several tuning options to further optimize performance:

    • -XX:ZCollectionInterval=<n>: Set the interval for concurrent collections (in milliseconds).
    • -XX:ZFragmentationLimit=<n>: Define the limit for memory fragmentation.
    • -XX:ZUncommitDelay=<n>: Set the delay before uncommitting memory.

  5. Monitoring and Logging: To monitor ZGC performance, you can enable logging using:

    -Xlog:gc*

Example Command

Here’s how you might initialize your application with ZGC enabled and include tuning options:

java -Xms1g -Xmx16g -XX:+UseZGC -XX:ZCollectionInterval=100 -Xlog:gc* -jar your-application.jar

This command demonstrates how to set specific heap sizes and logging while using ZGC.