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POUI thread sleeping even though postInvalidate() has been called to trigger onDraw()
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copied!<p>I have a problem with <code>postInvalidate</code> with my view. I have a thread called <code>MainFormViewRefresh</code> that wakes up periodically and only calls the <code>postInvalidate()</code> method for my view. This should wake the <code>main</code> UI thread and eventually call the view's <code>onDraw()</code> method and have it redrawn, but the main thread is just sleeping long times even when <code>postInvalidate()</code> is called.</p> <p>The UI thread is blocked on <code>MessageQueue#nativePollOnce</code> and it doesn't wake up from <code>postInvalidate()</code>. Why is it sleeping even when it has things to do? Is it missing my <code>postInvalidate()</code> calls? My understanding is that the <code>postInvalidate</code> should put an event in the queue and wake up the UI thread blocking on <code>nativePollOnce</code>. The CPU is only up to 50% because it is sleeping about half of the time.</p> <p>The picture illustrates the problem. Each spike of activity on MainFormViewRefresh ends with a call to <code>postInvalidate()</code>. The periods of inactivity in the main thread is time its spends blocked in <code>MessageQueue#nativePollOnce</code>. As can be seen, <code>postInvalidate()</code> is called several times without waking the main thread.</p> <p>The main period of activity on the <code>main</code> thread is <code>onDraw()</code> (blue).</p> <p><img src="https://i.stack.imgur.com/4vwid.jpg" alt="View of running threads"></p>

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