Bug 296822 NullProgressMonitor is not thread safe for expected usage
NullProgressMonitor.setCanceled and isCanceled access the cancelled field, but there's no synchronization. The expected use is that setCanceled is called from a thread other than the one doing the work, which polls isCanceled(), so this needs to be thread safe. Could either make these two methods synchronized or make the field volatile. Should check other progress monitor implementations too.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/ProgressMonitorDialog.java
* most cases. If <code>fork</code> is set to <code>false</code>, the
	 * runnable will run in the UI thread and it is the runnable's
	 * responsibility to call <code>Display.readAndDispatch()</code> to ensure
	 * UI responsiveness.
	 */
	public void run(boolean fork, boolean cancelable,
			IRunnableWithProgress runnable) throws InvocationTargetException,
			InterruptedException {
		setCancelable(cancelable);
		try {
			aboutToRun();
			
			progressMonitor.forked = fork;
			ModalContext.run(runnable, fork, getProgressMonitor(), getShell()
					.getDisplay());
		} finally {
			finishedRun();
		}
	}
	/**
	 * Returns whether the dialog should be opened before the operation is run.
	 * Defaults to <code>true</code>
	 * 
	 * @return <code>true</code> to open the dialog before run,
	 *         <code>false</code> to only create the dialog, but not open it
	 * @since 3.0
	 */
	public boolean getOpenOnRun() {
		return openOnRun;
	}