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    <p>The problem is that both threads are hitting the upper and lower bounds (50 and 0 respectively) at the same time. Both examples below highlight the deadlock.</p> <p>Scenario 1</p> <ol> <li>request(29) - freePages=21</li> <li>request(30) - under 0 so waits</li> <li>release(30) - over 50 so waits : deadlock</li> </ol> <p>Scenario 2</p> <ol> <li>request(29) - freePages=21</li> <li>release(30) - over 50 so waits</li> <li>request(30) - under 0 so waits : deadlock</li> </ol> <p>I am not sure what the exact requirements are for the homework problem but you need to revisit the release and request methods. I see two viable solutions:</p> <ol> <li>Change the release method so that it only releases up to MAX_FREE but will still return</li> <li>Change the release method so that it can release a subset of the amount requested, notifyAll, reenter the wait so it can release the remaining amount.</li> </ol> <p>Also, you are kind of using the ExecutionService wrong. The ExecutionService is what creates the Threads so there is no reason for you to create the threads like you are doing.</p> <pre><code>Thread t1 = new Thread(new MemAllocRequester(memoryAllocator)); Thread t2 = new Thread(new MemAllocReleaser(memoryAllocator)); </code></pre> <p>The threads you are creating will actually never be 'started' as Threads. It is still working for you because the ExecutionService threads will call your Thread.run() which will call MemAlloc*.run(). i.e. your t1 and t2 threads just pass the run() call along and provide no value.</p> <p>Your MemAllocRequester and MemAllocReleaser are Runnables so just pass those into the ExecutionService directly.</p> <pre><code>executor.submit(new MemAllocRequester(memoryAllocator)); executor.submit(new MemAllocReleaser(memoryAllocator)); </code></pre>
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    1. POTwo threads deadlocking but can't see why, lock released with notifyAll()
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    1. USLance Johnson
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    1. COGreat thanks for your help, it makes sense now. Also appreciate the exec service help!
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      1. USuser1089599
 

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