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/wizard/ProgressMonitorPart.java
protected ProgressIndicator fProgressIndicator;
    
    protected Control fCancelComponent;
    
    protected boolean fIsCanceled;
    
    protected IStatus blockedStatus;
    
    protected Listener fCancelListener = new Listener() {
        public void handleEvent(Event e) {
            setCanceled(true);
            if (fCancelComponent != null) {
				fCancelComponent.setEnabled(false);
			}
        }
    };
    /**
     * Creates a ProgressMonitorPart.
     * @param parent The SWT parent of the part.
     * @param layout The SWT grid bag layout used by the part. A client
     * can supply the layout to control how the progress monitor part
     * is layed out. If null is passed the part uses its default layout.
     */
    public ProgressMonitorPart(Composite parent, Layout layout) {
        this(parent, layout, SWT.DEFAULT);
    }
    /**
     * Creates a ProgressMonitorPart.
     * @param parent The SWT parent of the part.