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    <p>If the queue wraps around, it is possible that byte arrays get reused and overwritten before having been read by consumers. In short, you'd need to have a <code>commitGet</code> method to make sure that producers wait for consumers before overwriting an array with new data.</p> <p>However, my suggestion is that you rely on <a href="http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/BlockingQueue.html" rel="nofollow">java.util.concurrent.BlockingQueue</a> having a second queue to return them from consumers back to the producer, and on <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/ByteBuffer.html" rel="nofollow">java.nio.ByteByffer</a> to keep track of lengths. The producer would do as follows:</p> <pre><code>ByteBuffer buffer = bufferQueue.poll(); // instead of your put() buffer.put(source); // fill buffer from source MappedByteBuffer buffer.flip(); // set length to the amount written dataQueue.offer(buffer); // instead of commitPut() </code></pre> <p>The consumer would:</p> <pre><code>ByteBuffer buffer = dataQueue.poll(); // instead of your get() buffer.get(...); // use data buffer.clear(); // reset length bufferQueue.offer(buffer); // this is the missing commitGet() </code></pre> <p>You should initially insert <code>capacity</code> elements in <code>freeQueue</code>. Note however that this will still copy data once from the <code>source</code> buffer into temporary buffers in the queues, as your original code already did.</p> <p>If you really don't want to copy data (and are sure that the source does not change until all consumers have read it!), your better option is to use a single blocking queue and insert buffers obtained with <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/ByteBuffer.html#slice%28%29" rel="nofollow">ByteBuffer.slice()</a> from your source buffer for each chunk of data to be handed down to consumers. These will then be garbage collected, but should take much less memory than the byte arrays themselves.</p>
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    1. COthanks for helping out. Why I am trying to reuse byte arrays - before I was using simple ArrayBlockingQeueu with Bitmaps. I have producer that was filling the qeueu and consumer (drawer) consuming bitmaps. This was working, at least I thought, until I tried it on some "funny" low budget android tablet where GC is kicking in all the time for even smallest allocations (in total I am using 10MB out of 48 allowed, so not even close to understand why GC is so aggresive on this tablet). For this reason I decided to try with fixed allocated byte array, reusing it and not giving GC reason start.
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    2. COI see. Using a second queue to return empty arrays should do it safely.
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    3. COI am still trying to wrap my head arround your two queue concept... Can you please explain it again? If I have producer "reader" which wants to read bytes from a MappedByteBuffer directly to "readers" queue (to avoid byte copying) and wait when queue is full, and consumer "drawer" which consumes bytes from the readers queue. Because byte arrays are fixed length (to accomodate largest bitmap) I still need to keep track of "byte lengths" for each queue slot.
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