RFR(S): 6952105 TEST_BUG: testcase failure, not very often, com/sun/jdi/SuspendThreadTest.java

[shanliang]

I am looking at the old file:
 143         while (bkptCount < maxBkpts) {
 144             prevBkptCount = bkptCount;

suppose the following execution sequence:
1)   when Line 143 was called by Thread1, we had bkptCount == maxBkpts - 1;
 
2) bkptCount++ was executed by thread2;

3) Line 144 was called by thread1,

in this case it was sure that the line
    152                 failure("failure: test hung");
would be called.

It is good to add:
    synchronized (bkptSignal)
in the fix, but we need to put Line 143 and 144 into synchronization too.

To deal with a spurious wakeup, we might do like this:
        long stopTime = System.currentTimeMillis() + 5000;
        do {
            try {
                bkptSignal.wait(100);
            } catch (InterruptedException e){}
        } while(prevBkptCount == bkptCount && System.currentTimeMillis() 
< stopTime);

Shanliang

David Holmes wrote:
> On 18/02/2014 11:03 PM, Staffan Larsen wrote:
>>
>> On 18 feb 2014, at 13:09, David Holmes <david.holmes at oracle.com> wrote:
>>
>>> Hi Staffan,
>>>
>>> If you get a spurious wakeup from wait():
>>>
>>> 151             try {
>>> 152                 synchronized (bkptSignal) {
>>> 153                     bkptSignal.wait(5000);
>>> 154                 }
>>> 155             } catch (InterruptedException ee) {
>>> 156             }
>>> 157             if (prevBkptCount == bkptCount) {
>>> 158                 failure("failure: test hung");
>>>
>>> you could report failure. But that is far less likely than the 
>>> current problem using sleep.
>>
>> Right. Adding “continue;” inside the catch(InterruptedException) 
>> block should guard against that.
>
> No, a spurious wakeup is not an interrupt - the wait() will simply 
> return.
>
> David
>>
>> /Staffan
>>
>>>
>>> David
>>>
>>> On 18/02/2014 8:19 PM, Staffan Larsen wrote:
>>>> Still looking for Reviewer for this change.
>>>>
>>>> Thanks,
>>>> /Staffan
>>>>
>>>> On 11 feb 2014, at 15:12, Staffan Larsen 
>>>> <staffan.larsen at oracle.com> wrote:
>>>>
>>>>> Updated the test to use proper synchronization and notification 
>>>>> between threads. Should be more stable and much faster.
>>>>>
>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-6952105
>>>>> webrev: http://cr.openjdk.java.net/~sla/6952105/webrev.00/
>>>>>
>>>>> Thanks,
>>>>> /Staffan
>>>>
>>