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

[David Holmes]

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!).

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?

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
>