RFR: 8240222: [TESTBUG] gtest/jfr/test_networkUtilization.cpp failed when the number of tests is greater than or equal to 2

[Jia Huang]

Haha, I'm also trying to email hotspot-jfr-dev.
Thank you, David.

在 2020/3/9 13:03, David Holmes 写道:
> Hi Jia,
>
> I see this is getting no response so have cc'd hotspot-jfr-dev as they 
> should have a better idea of how this gtest can and cannot be used.
>
> Just because the GTest framework supports "REPEAT" it doesn't mean all 
> tests can, or should, be repeatable.
>
> Cheers,
> David
>
> On 29/02/2020 1:53 pm, Jia Huang wrote:
>> Hi David,
>>
>> 在 2020/2/28 21:16, David Holmes 写道:
>>> Hi Jia,
>>>
>>> On 28/02/2020 11:08 pm, Jia Huang wrote:
>>>> Hi all,
>>>>
>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8240222
>>>> Webrev: http://cr.openjdk.java.net/~jiahuang/8240222/webrev.00/
>>>>
>>>> gtest/jfr/test_networkUtilization.cpp failed when the number of 
>>>> tests is greater than or equal to 2.
>>>> As shown in the following code, the test failed because "traceid 
>>>> id" is a static local variable.
>>>> When the test runs a second time, "id" continues to grow, resulting 
>>>> in the return value of "i" being "_interfaces.end()".
>>>
>>> Interesting! I'm not at all familiar with the details of gtest and 
>>> how it actually runs things. But I would expect that we have many 
>>> tests that rely on starting from a cleanly initialized VM state, or 
>>> test state, and so can't simply be repeated (it would be like 
>>> editing an arbitrary test and putting the body of main into a 
>>> for-loop!).
>>
>> I'm sorry that my last description may be a little incomplete.
>> JfrTestNetworkUtilization is a group of tests,it includes four 
>> individual tests:
>>    --JfrTestNetworkUtilization.RequestFunctionBasic_test_vm
>>    --JfrTestNetworkUtilization.RequestFunctionMultiple_test_vm
>>    --JfrTestNetworkUtilization.InterfaceRemoved_test_vm
>>    --JfrTestNetworkUtilization.InterfaceReset_test_vm
>>
>> If you only run a individual test once, such as the following 
>> Testing, it still fails.
>> The reason for the failure, as I said last time, is also because of 
>> static local variables.
>> In the "RequestFunctionMultiple_test_vm" test, the sequence number of 
>> "eth0" is 2.
>> However, the initial value of the static local variable "id" is 0.
>>
>> Testting:
>>     --make run-test 
>> TEST=gtest:JfrTestNetworkUtilization.RequestFunctionMultiple_test_vm 
>> GTEST=REPEAT=1 CONF=release
>>     --make run-test 
>> TEST=gtest:JfrTestNetworkUtilization.InterfaceRemoved_test_vm 
>> GTEST=REPEAT=1 CONF=release
>>     --make run-test 
>> TEST=gtest:JfrTestNetworkUtilization.InterfaceReset_test_vm 
>> GTEST=REPEAT=1 CONF=release
>>
>>>
>>> So I'm not sure what the right way to fix this is:
>>> - don't use REPEAT?
>>> - declare the test as not repeatable somehow?
>>> - change the test to make it repeatable?
>>
>> In the doc/testing.md or doc/testing.html, Gtest keywords inclue 
>> "REPEAT",
>> so I think this means that all GTEST tests should be able to use the 
>> "REPEAT parameter.
>>
>>
>> Best regards,
>> Jia
>>
>>
>>>
>>> Cheers,
>>> David
>>>
>>>> ---------------------------------------------------------------------------- 
>>>>
>>>> test/hotspot/gtest/jfr/test_networkUtilization.cpp
>>>>
>>>> static const MockNetworkInterface& get_interface(traceid id) {
>>>>    std::list<MockNetworkInterface>::const_iterator i = 
>>>> _interfaces.begin();
>>>>    for (; i != _interfaces.end(); ++i) {
>>>>      if (i->id == id) {
>>>>        break;
>>>>      }
>>>>    }
>>>>    return *i;
>>>> }
>>>> ---------------------------------------------------------------------------- 
>>>>
>>>>
>>>>
>>>> Testing:
>>>>      - make run-test TEST=gtest:JfrTestNetworkUtilization 
>>>> GTEST=REPEAT=2 CONF=server-release
>>>>      - make run-test TEST=gtest:JfrTestNetworkUtilization 
>>>> GTEST=REPEAT=2 CONF=server-fastdebug
>>>>
>>>> Thanks a lot
>>>>
>>>> Best regards,
>>>> Jia
>>>>
>>