／var／logmarcus chiu

Java - Garbage Collector Logging

Created on

Simple Java Program

public class Application {
 
    private static Map<String, String> stringContainer = new HashMap<>();
 
    public static void main(String[] args) {
        System.out.println("Start of program!");
        String stringWithPrefix = "stringWithPrefix";
 
        // Load Java Heap with 3 M java.lang.String instances
        for (int i = 0; i < 3000000; i++) {
            String newString = stringWithPrefix + i;
            stringContainer.put(newString, newString);
        }
        System.out.println("MAP size: " + stringContainer.size());
 
        // Explicit GC!
        System.gc();
 
        // Remove 2 M out of 3 M
        for (int i = 0; i < 2000000; i++) {
            String newString = stringWithPrefix + i;
            stringContainer.remove(newString);
        }
 
        // Explicit GC!
        System.gc(); 
 
        System.out.println("MAP size: " + stringContainer.size());
        System.out.println("End of program!");
    }
}

Run Simple Java Program With Simple GC Logging

Run Simple Java Program With Verbose GC Logging

Adding Date and Time Information

Logging to a File

Resources