RFR 8035395: sun/management/jmxremote/startstop/JMXStartStopTest.java fails intermittently: Port already in use

[Jaroslav Bachorik]

Hi Shanliang,

On 20.2.2014 19:20, shanliang wrote:
> Jaroslav,
>
> The failed tests were:
>     1, 7, 8, 9
>
> but the tests using this port (port2: 50235) were
>     1, 3, 4, 6, 7, 8, 9
>
> and tests 2,4,6 were passed.
>
> so I think that the problem might be that the port was not fully
> released when a test was trying to use it, even the port was closed by
> the previous test.

I don't think this is the case.

Firstly, test 1 fails. There are no previous tests possibly holding on 
to the required port. So the port must have been taken by some foreign 
process. The port number being from the ephemeral range doesn't help 
either, quite contrary.

Secondly, a port can not be partially bound - either a process binds to 
a port or not. Also, when a process exits all the bound ports must be 
released. Since we are waiting for the exit code of the launched test 
application before proceeding all the ports used by that application 
must be released before the main test routine can continue.

>
> Your solution is to create a Server socket on a free port, then release
> it when a test needs it. I suspect whether we will fall into same issue
> here: the port would not be fully released when using it?

No. SocketServer.close() is called synchronously right before the port 
is going to be used. This call unbinds the socket and returns. At the 
moment of the return the port is free. I've run the tests locally and 
via JPRT and they are all passing.

Thanks,

-JB-

>
> Shanliang
>
> Jaroslav Bachorik wrote:
>> Please, review this test fix.
>>
>> Issue : https://bugs.openjdk.java.net/browse/JDK-8035395
>> Webrev: http://cr.openjdk.java.net/~jbachorik/8035395/webrev.00
>>
>> Currently, the test is using two fixed ports to start JMX connector
>> and RMI registry when necessary. It can not deal with situations when
>> the ports are not available. The patch is adding the ability to obtain
>> ports from the ephemeral range and use them instead of the hardcoded
>> ones. It also tries to minimize the chance of another process stealing
>> the ports by holding the corresponding SocketServers open till right
>> before the port is actually needed.
>>
>> Thanks,
>>
>> -JB-
>