Java Garbage Collection Logging

Internal

• Java Garbage Collection

Command Line Options

Java 8

https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html#BABFAFAE

Overview

In Java 8, GC logging is enabled with the -Xloggc:<file> (see below). The actual -XX values the JVM operates with are displayed at the top of the log file:

...
CommandLine flags: -XX:InitialHeapSize=268435456 -XX:MaxHeapSize=4294967296 -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
...

Options

-Xloggc:

-Xloggc:<file>

where <file> can be absolute or relative. In case of a relative path, it is relative to the current directory.

-XX:+PrintGC

-XX:+PrintGC

Enables printing of messages at every GC. By default, this option is disabled, but -Xloggc:<file> turns it on implicitly.

-XX:+PrintGCTimeStamps

-XX:+PrintGCTimeStamps

Enables printing of time stamps (time in seconds since the JVM started) at every GC. By default, this option is disabled. Time stamps recorded this way provide a chronology relative to the time the JVM started, but additional calculation is needed to translate the timestamps to normal timestamps; this is only possible if the JVM start time is also recorded. A better way to record timestamps is to use [[]].

-XX:+PrintGCDateStamps=

-XX:+PrintGCDateStamps

-verbose:gc

-XX:+PrintGCDetails

-XX:+PrintGCDateStamps

-XX:+UseGCLogFileRotation

-XX:NumberOfGCLogFiles=5

-XX:GCLogFileSize=3M