GC closes my ServerSocket

[Chris Hegarty]

Looks fine to me. Thanks for adding the finally block.

-Chris.

On 13/06/2012 11:50, Weijun Wang wrote:
> Updated:
>
> http://cr.openjdk.java.net/~weijun/7176574/webrev.01/
>
> Thanks
> Max
>
> On 06/13/2012 05:52 PM, Chris Hegarty wrote:
>>
>>
>> On 13/06/2012 10:23, Weijun Wang wrote:
>>> Please anyone take a review:
>>>
>>> http://cr.openjdk.java.net/~weijun/7176574/webrev.00/
>>>
>>> By assigning to a local variable hopefully it stays alive on the stack
>>> during the whole method.
>>
>> If they don't then we have a real problem ;-)
>>
>>> Noreg-self.
>>>
>>> *Chris*: I didn't indented the whole test by wrapping them into a
>>> try-finally (or try-with-resources) block. The test runs in othervm and
>>> I guess the sockets will be closed anyway.
>>
>> Strictly speaking, after the construction of these ServerSocket instance
>> you should wrap the remainder of the code in a try finally to ensure
>> that close is called. Even with othervm mode when the vm is exiting
>> there is not guarantee that finalizers are run.
>>
>> I think it would be best to add a finally block here to reduce the
>> chances of strange/intermittent behavior as a result of running this
>> test. Either the test itself or excessive resource hogging on the
>> system. But if you are really against it, I can live with what you
>> have ;-)
>>
>> -Chris.
>>
>>>
>>> Thanks
>>> Max
>>>
>>> On 06/13/2012 05:08 PM, Chris Hegarty wrote:
>>>>
>>>>
>>>> On 13/06/2012 09:51, Alan Bateman wrote:
>>>>> On 13/06/2012 09:38, Weijun Wang wrote:
>>>>>> Hi All
>>>>>>
>>>>>> I have a test that basically looks like:
>>>>>>
>>>>>> int p = new ServerSocket(0).getLocalPort();
>>>>>> //....
>>>>>> new Socket("localhost", p);
>>>>>>
>>>>>> Recently it's failing on solaris-i586, and after some
>>>>>> investigation, I
>>>>>> realize that the ServerSocket object is GC'ed and auto-closed.
>>>>>>
>>>>>> (But why only recently?)
>>>>>>
>>>>>> So I change the first line to
>>>>>>
>>>>>> ServerSocket ss = new ServerSocket(0);
>>>>>> int p = ss.getLocalPort();
>>>>>>
>>>>>> and it's running fine.
>>>>>>
>>>>>> I want to know if the ServerSocket object still has a chance to be
>>>>>> closed. If yes, I'll add a
>>>>>>
>>>>>> ss.close();
>>>>>>
>>>>>> at the end to be safer.
>>>>>>
>>>>>> Thanks
>>>>>> Max
>>>>> HotSpot changes I assume, perhaps changes to the reference
>>>>> processing or
>>>>> default heap settings.
>>>>
>>>> Right, I assume there was some VM change that started this test to fail
>>>> recently, but clearly this is a test issue. It was just passing all
>>>> this
>>>> time by accident, and there is an inherent race between the test and
>>>> the
>>>> GC/finalizer thread.
>>>>
>>>> You should fix the test as you suggested. Also close the
>>>> serversocket in
>>>> a finally block ( or equivalent ). You should not rely on the finalizer
>>>> to close it out.
>>>>
>>>> -Chris.
>>>>
>>>>>
>>>>> -Alan