de.ipcon.tools

Class G1FootprintHelper

java.lang.Object

java.lang.Thread

de.ipcon.tools.G1FootprintHelper

All Implemented Interfaces:

java.lang.Runnable

public class G1FootprintHelper
extends java.lang.Thread

This class was created upon the desperate need to have a minimum footprint for our software, but a few obstacles in the way: - incgc is going to be deprecated, if not removed, in Java 9 - string deduplication, which brings a tremendous reduction in heap size, is only available in g1gc - g1gc, for some reason, doesn't do a full gc on it's own, even if there's loads of free heap available which could be returned to the OS For the above reasons, this class will only work correctly if the following JVM options are set: - either no -XX:-DisableExplicitGC or no -XX:+DisableExplicitGC option is given (which would suppress our efforts here...) - -XX:+UseG1GC - -XX:+UseStringDeduplication (optional) The class will only do anything if at least the system property 'autogc.interval' is set to a non-zero value. The configuration is done via system properties, as follows: - autogc.interval interval in minutes checks are done - autogc.minInterval minimum interval in minutes a full gc can be done after the last one - autogc.maxFreeRatio free/total ratio which needs to be exceeded to trigger a full gc - autogc.minFreeHeap minimum available free memory to allow a full gc - autogc.warnThreshold issue a warning into the log if the full gc takes longer than this milliseconds

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Method Summary

Modifier and Type	Method and Description
static boolean	active()
static G1FootprintHelper	getInstance()
static void	main(java.lang.String[] args)
java.lang.String	memInfo()
void	run()
static void	suggestGC()

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getInstance

public static G1FootprintHelper getInstance()

active

public static boolean active()

suggestGC

public static void suggestGC()

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

memInfo

public java.lang.String memInfo()

main

public static void main(java.lang.String[] args)