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    <p>The problem is a class producer/consumer problem. Your code as it stands doesn't really make sense - you cannot use a single condition variable for waiting on both sides, (remember you call notify then wait - on the same condition, in the same context.) So anything can happen.</p> <p>You need to refactor your code to use two condition variables, one for the producer, one for the consumer, for example:</p> <p>EDIT: Updated with a pure c++11 implementation which should be correct.</p> <pre><code>#include &lt;atomic&gt; #include &lt;chrono&gt; #include &lt;condition_variable&gt; #include &lt;iostream&gt; #include &lt;mutex&gt; #include &lt;thread&gt; using namespace std; mutex mutex_; condition_variable con_, prd_; atomic_bool done_{false}, process_{false}; // possibly overkill, but hey-ho int counter = 0; // protected resource void consumer() { for (;;) { unique_lock&lt;mutex&gt; lock(mutex_); // acquire the mutex before waiting // this is the correct way to wait on the condition (as highlighted by @Dale) con_.wait(lock, []{ return process_.load() || done_.load(); }); if (!done_.load()) { cout &lt;&lt; counter &lt;&lt; endl; process_.store(false); // we're done with this item lock.unlock(); // release before notifying prd_.notify_one(); } else break; // we're done completely } } void producer() { unique_lock&lt;mutex&gt; lock(mutex_); for (int i = 0; i &lt; 10; ++i) { this_thread::sleep_for(chrono::milliseconds(500)); ++counter; process_.store(true); // indicate that there is data con_.notify_one(); // wait for the consumer to complete prd_.wait(lock, []{ return !process_.load(); }); } done_.store(true); // we're done lock.unlock(); // release before notifying con_.notify_one(); } int main(void) { thread c(consumer); producer(); c.join(); } </code></pre> <p>So now what happens is, the consumer waits on it's condition (and only the producer will call <code>notify()</code> on this), and the producer, once it has produced something calls this notify which will wake the client up. The client will then call <code>notify()</code> to wake the producer up.</p> <p>The above updated approach should not suffer the spurious wake up problem as I highlighted before. This negates the need for a <code>timed_wait</code>.</p>
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    1. COthanks for reply, but it did not work.
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    2. COthere is dedelock somehow code simply hangs after printing some values , however if i debug step by step things work fine.
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    3. CO@vivek - see the answer now..
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