RFR: JDK-8204994: SA might fail to attach to process with "Windbg Error: WaitForEvent failed"

[serguei.spitsyn at oracle.com]

Hi Alex,

Thank you for the update!
LGTM.

Thanks,
Serguei


On 5/29/20 13:35, Alex Menkov wrote:
> Hi Serguei,
>
> ok, I added the loop.
> webrev:
> http://cr.openjdk.java.net/~amenkov/jdk15/WinDbg_WaitForEvent/webrev.2/
>
> --alex
>
> On 05/28/2020 20:35, serguei.spitsyn at oracle.com wrote:
>> Hi Alex,
>>
>> It'd be nice to reduce noise from such intermittent issues and also 
>> get rid of such bugs in the future.
>> My gut feeling is that we just significantly reduced a probability of 
>> this failure in something
>> like an order of magnitude but it will still happens once in a month 
>> or a half of year.
>> This issue should go away completely with 3 or 4 iterations.
>> The price is not high as the 3rd iteration is going to be rare and 
>> the 4th should never happen.
>> Also, it would not increase complexity.
>>
>> But no pressure, you are to decide.
>> I'm just sharing my opinion.
>>
>> Thanks,
>> Serguei
>>
>>
>> On 5/28/20 17:04, Alex Menkov wrote:
>>> Hi Serguei,
>>>
>>> With my testing 2nd call always succeeded, but I was able to 
>>> reproduce the case only 3 times with my test runs.
>>> I can implement the loop, but number of retries is anyway an 
>>> arbitrary value.
>>>
>>> --alex
>>>
>>> On 05/28/2020 15:44, serguei.spitsyn at oracle.com wrote:
>>>> Hi Alex,
>>>>
>>>> It looks good in general.
>>>>
>>>> +static HRESULT WaitForEvent(IDebugControl *ptrIDebugControl) {
>>>> + // see JDK-8204994: sometimes WaitForEvent fails with 
>>>> E_ACCESSDENIED,
>>>> + // but succeeded on 2nd call.
>>>> + HRESULT hr = ptrIDebugControl->WaitForEvent(DEBUG_WAIT_DEFAULT, 
>>>> INFINITE);
>>>> + if (hr == E_ACCESSDENIED) {
>>>> + // yield current thread use of a processor (short delay).
>>>> + SwitchToThread();
>>>> + hr = ptrIDebugControl->WaitForEvent(DEBUG_WAIT_DEFAULT, INFINITE);
>>>> + }
>>>> + return hr;
>>>> +}
>>>>
>>>>
>>>> Can the ptrIDebugControl->WaitForEvent fail with E_ACCESSDENIED 
>>>> twice and succeed on third call?
>>>> Would it better to make it a loop with more retry attempts?
>>>>
>>>> Thanks,
>>>> Serguei
>>>>
>>>>
>>>> On 5/27/20 13:54, Alex Menkov wrote:
>>>>> Hi all,
>>>>>
>>>>> please review the fix for
>>>>> https://bugs.openjdk.java.net/browse/JDK-8204994
>>>>> webrev:
>>>>> http://cr.openjdk.java.net/~amenkov/jdk15/WinDbg_WaitForEvent/webrev/
>>>>>
>>>>> --alex
>>>>
>>