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

[Jia Huang]

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
>>