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copied!<p>I can't be completely sure what the problem is since I have no clue what the <code>ShowSensorData()</code> function (method?) is doing, but there are some multithreading issues with the code that you have included.</p> <ol> <li><code>mUpdate</code> should be protected by a mutex if it is accessed by more than one thread.</li> <li>The <code>run()</code> method looks like it will lock the mutex and never release it if <code>mStop</code> is true.</li> </ol> <p>You should consider using <a href="http://en.wikipedia.org/wiki/RAII" rel="nofollow noreferrer">RAII</a> practices to grab and release the mutex. I don't know if you are using Qt mutexes or not but you should look into using <a href="http://doc.trolltech.com/4.5/qmutexlocker.html" rel="nofollow noreferrer">QMutexLocker</a> to lock and unlock your mutexes.</p> <p>I would consider changing your <code>SensorProtocol</code> class to use the condition variable and a flag or some sort of event (not sure what Qt has to offer here) to handle the update inside of a method associated with the object instance. Something like:</p> <pre><code>/*static*/ void SensorProtocol::updateSensorProtocol() { SensorProtocol *inst = SensorProtocol::getInstance(); inst->update(); } </code></pre> <p>Then make sure that the <code>update()</code> method grabs the mutex before reading or writing any of the members that are shared between the reader and display.</p> <p>A more complete approach would be to separate your UI display, the sensors, and their linkage using a <a href="http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller" rel="nofollow noreferrer">Model-View-Controller</a> architecture. Refactoring the solution into an MVC architecture would probably simplify things quite a bit. Not to mention that it makes applications like this a lot less error-prone. Take a look at the <a href="http://doc.trolltech.com/4.5/qabstractitemview.html" rel="nofollow noreferrer">QAbstractItemView</a> and <a href="http://doc.trolltech.com/4.5/qabstractitemdelegate.html" rel="nofollow noreferrer">QAbstractItemDelegate</a> classes for an idea on how this can be implemented. From what I remember, there is a tutorial about implementing MVC using Qt somewhere... it's been quite a few years since I have played with Qt though.</p>

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