Package edu.wisc.ssec.mcidasv.util.gui

Class EventDispatchThreadHangMonitor

java.lang.Object

java.awt.EventQueue

edu.wisc.ssec.mcidasv.util.gui.EventDispatchThreadHangMonitor

public final class EventDispatchThreadHangMonitor
extends EventQueue

Monitors the AWT event dispatch thread for events that take longer than a certain time to be dispatched.

The principle is to record the time at which we start processing an event, and have another thread check frequently to see if we're still processing. If the other thread notices that we've been processing a single event for too long, it prints a stack trace showing what the event dispatch thread is doing, and continues to time it until it finally finishes.

This is useful in determining what code is causing your Java application's GUI to be unresponsive.

The original blog can be found here
Automatically detecting AWT event dispatch thread hangs

Author:

Elliott Hughes invalid input: '<'enh@jessies.org> Advice, bug fixes, and test cases from Alexander Potochkin and Oleg Sukhodolsky. https://swinghelper.dev.java.net/

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	EventDispatchThreadHangMonitor.DispatchInfo
private class	EventDispatchThreadHangMonitor.HangChecker
private static class	EventDispatchThreadHangMonitor.Tests

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	CHECK_INTERVAL_MS
private final LinkedList<EventDispatchThreadHangMonitor.DispatchInfo>	dispatches
private static int	hangCount
private boolean	haveShownSomeComponent
private static final EventDispatchThreadHangMonitor	INSTANCE
private static final org.slf4j.Logger	logger
private static final long	UNREASONABLE_DISPATCH_DURATION_MS

Constructor Summary

Constructors

Modifier	Constructor	Description
private	EventDispatchThreadHangMonitor()

Method Summary

Modifier and Type	Method	Description
private static void	checkForDeadlock()
protected void	dispatchEvent(AWTEvent event)	Overrides EventQueue.dispatchEvent to call our pre and post hooks either side of the system's event dispatch code.
private static int	getNewHangNumber()
static void	initMonitoring()	Sets up hang detection for the event dispatch thread.
private void	initTimer()	Sets up a timer to check for hangs frequently.
static void	main(String[] args)
private void	postDispatchEvent()	Stops tracking a dispatch.
private void	preDispatchEvent()	Starts tracking a dispatch.
private static String	stackTraceToString(StackTraceElement[] stackTrace)

Methods inherited from class java.awt.EventQueue

createSecondaryLoop, getCurrentEvent, getMostRecentEventTime, getNextEvent, invokeAndWait, invokeLater, isDispatchThread, peekEvent, peekEvent, pop, postEvent, push

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

logger

private static final org.slf4j.Logger logger

INSTANCE

private static final EventDispatchThreadHangMonitor INSTANCE

CHECK_INTERVAL_MS

private static final long CHECK_INTERVAL_MS

See Also:

• Constant Field Values

UNREASONABLE_DISPATCH_DURATION_MS

private static final long UNREASONABLE_DISPATCH_DURATION_MS

See Also:

• Constant Field Values

hangCount

private static int hangCount

haveShownSomeComponent

private boolean haveShownSomeComponent

dispatches

private final LinkedList<EventDispatchThreadHangMonitor.DispatchInfo> dispatches

Constructor Details

EventDispatchThreadHangMonitor

private EventDispatchThreadHangMonitor()

Method Details

initTimer

private void initTimer()

Sets up a timer to check for hangs frequently.

initMonitoring

public static void initMonitoring()

Sets up hang detection for the event dispatch thread.

dispatchEvent

protected void dispatchEvent(AWTEvent event)

Overrides EventQueue.dispatchEvent to call our pre and post hooks either side of the system's event dispatch code.

Overrides:

dispatchEvent in class EventQueue

preDispatchEvent

private void preDispatchEvent()

Starts tracking a dispatch.

postDispatchEvent

private void postDispatchEvent()

Stops tracking a dispatch.

checkForDeadlock

private static void checkForDeadlock()

stackTraceToString

private static String stackTraceToString(StackTraceElement[] stackTrace)

getNewHangNumber

private static int getNewHangNumber()

main

public static void main(String[] args)