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    <p>You're right that there's a race there. <code>FutureTask#done()</code> will be called <em>at most once</em>, so if the task has already been canceled before it was ever run via <code>RunnableFuture#run()</code>, you'll have missed the call to <code>FutureTask#done()</code>.</p> <p>Have you considered a simpler approach that always issues a symmetric set of paired calls to <code>ITaskStatusHandler#taskRunning()</code> and <code>ITaskStatusHandler#taskCompleted()</code>, like so?</p> <pre><code>@Override public void run() { statusHandler.TaskRunning(this); try { super.run(); finally { statusHandler.TaskCompleted(this); } } </code></pre> <p>Once <code>RunnableFuture#run()</code> is called, it's true that your task in running, or at least trying to be run. Once <code>FutureTask#run()</code> is done, your task is no longer running. It so happens that in the case of cancellation, the transition is (nearly) immediate.</p> <p>Trying to avoid calling <code>ITaskStatusHandler#taskRunning()</code> if the inner <code>Callable</code> or <code>Runnable</code> is never invoked by <code>FutureTask#run()</code> will require you to establish some shared structure between the <code>Callable</code> or <code>Runnable</code> and the <code>FutureTask</code>-derived type itself, so that when your inner function is first called you set some flag that the outer <code>FutureTask</code>-derived type can observe as a latch, indicating that yes, the function did start running <em>before</em> having been canceled. However, by then, you had to have committed to calling <code>ITaskStatusHandler#taskRunning()</code>, so the distinction isn't so useful.</p> <p>I've been struggling with a similar design problem lately, and wound up settling on the symmetric <em>before</em> and <em>after operations</em> in my overridden <code>FutureTask#run()</code> method.</p>
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    1. COI assume the call in the finally clause should be statusHandler.TaskCompleted(this); Is there any case where the run method would not be called but the done() method would ?
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    2. COThanks for catching the mistake. I fixed the call in the finally block. Yes, it's possible that done() can be called without run() having been called. See FutureTask#Sync#innerCancel(boolean). There, provided that the task has not finished running, which includes it never having started running, you can see that done() will be called. Note that done() will be called zero or one times for any FutureTask instance: zero if neither run() nor cancel() is never called, once otherwise.
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    3. COSeems though, if you submit it to an executor done() will be called if the task is cancelled before it is executed - although the executor doesn't know about that. The executor only knows about runnables/callables. So, run() will be called when it eventually becomes runnable in that case FutureTask#run() essentially does nothing though.
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