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POCan I seek a file from different threads independently using FileChannel?
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  1. POCan I seek a file from different threads independently using FileChannel?
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    copied!<p>I created a web application that works on FLV files.</p> <p>This application uses a library that I created for parsing content from flv files. This library uses FileChannel to seek a file.</p> <p>I'm experiencing a strange behavior now that I seek the same flv file from different threads. Let's say that <strong>Thread_1</strong> and <strong>Thread_2</strong> are both seeking <strong>movie.flv</strong> concurrently (my question comes after the example).</p> <p><strong>Thread_1</strong></p> <pre><code>// Thread_1 moves to position 200 to read something FileChannel chan1 = new FileInputStream("movie.flv").getFileChannel(); chan1.position(200); </code></pre> <p><strong>Thread_2</strong> (executing just after <strong>Thread_1</strong>)</p> <pre><code>// Thread_2 moves to position 600 to read something else FileChannel chan2 = new FileInputStream("movie.flv").getFileChannel(); chan2.position(600); </code></pre> <p>Finally <strong>Thread_1</strong> does:</p> <pre><code>ByteBuffer bb = ByteBuffer.allocate(40); chan1.read(bb); </code></pre> <p>Is <strong>Thread_1</strong> reading 40 bytes from position 200 or from position 600? More precisely, are <em>chan1</em> and <em>chan2</em> independent (=can seek independently) channels or not?</p> <p>From the <a href="http://docs.oracle.com/javase/6/docs/api/java/io/FileInputStream.html#getChannel%28%29" rel="nofollow">documentation</a> I read that the FileChannel is <strong>unique</strong>, so my bet (unfortunately) is that in the example <strong>Thread_1</strong> is going to read from position 600 :\</p> <p>In case, can you suggest a different approach for seeking a file independently from different threads?</p> <p>thanks!</p>
 

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