Andrew Zhang wrote:
> Hello everybody,
>
> I noticed such tests in DatagramChannel, which is useful, but potentially
> unstable. Consider:
>
> public void testReadWrite_configureBlock() throws Exception {
> byte[] targetArray = new byte[2];
> // bind and connect
> this.channel1.socket().bind(localAddr2);
> this.channel1.connect(localAddr1);
> this.channel2.socket().bind(localAddr1);
> this.channel2.connect(localAddr2);
> ByteBuffer targetBuf = ByteBuffer.wrap(targetArray);
>
> new Thread() {
> public void run() {
> try {
> Thread.sleep(TIME_UNIT);
> channel1.configureBlocking(false); // Label 1
> channel1.close(); // Label 2
> } catch (Exception e) {
> //ignore
> }
> }
> }.start();
> try {
> this.channel1.read(targetBuf); // Label 3
> fail("should throw AsynchronousCloseException");
> } catch (AsynchronousCloseException e) {
> // ok
> }
> }
> This test assumes Label 3 code should execute before Label 1 and Label 2,
> which is right in most cases, because the code invokes "Thread.sleep
> (TIME_UNIT)".
>
> However, it's potentially unstable. It heavily depends on TIME_UNIT value,
> test environment (Hardware, OS ...)
Urgh. There are *very* few occasions when you need to use
Thread.sleep(); and 'thread synchronization' is definitely not one of them!
If you have order dependencies between two or more threads then use
wait/notify, or synchronized, and make them explicit.
There are any number of books on multi-threaded programming in Java.
> Indubitably, the test is very useful for testing
> "AsynchronousCloseException" of DatagramChannel.read(ByteBuffer) method.
>
> How shall we deal with such issue? Deleting such valuable tests is not a
> wise decision, while keeping them may cause build system fail.
>
> One solution I could image is TestNG. :) i.e. Use "@dev" or something to
> mark such tests, say, the tests are only for developing purpose.
>
> Any suggestions?
Fix it! :-)
Regards,
Tim
--
Tim Ellison ([EMAIL PROTECTED])
IBM Java technology centre, UK.
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