RFR [XS]: 8229370: make jdk/jfr/event/runtime/TestNetworkUtilizationEvent.java more stable

[Mikhailo Seledtsov]

On 8/27/19, 1:15 AM, Baesken, Matthias wrote:
> Hi  David,   thanks for  the info about
>
> https://bugs.openjdk.java.net/browse/JDK-8228990
>
>
> regarding your comment in the bug :
>
>> So it makes no sense. I finally found an example where the test passed and failed on the same machine.
> I've seen this too .
>
> Looks like  my change  only  increased  the probability of  incidental network traffic happening  on the real network interfaces .
>
> Should we exclude the test,  in the current state it might indeed be problematic .
>
> (otherwise we could make the test pass  on Linux  when just 1 network interface is found,  this might be a legitimate case isn’t it ?)
Based on David's analysis in the "JDK-8228990: [TESTBUG] JFR 
TestNetworkUtilizationEvent.java expects 2+ Network interfaces on Linux 
but finding 1", my opinion is to remove the check for number of 
interfaces all together. Or just check that there is 1 interface.

Misha
>
>
> Best regards, Matthias
>
>
>
>> -----Original Message-----
>> From: David Holmes<david.holmes at oracle.com>
>> Sent: Dienstag, 27. August 2019 09:56
>> To: Baesken, Matthias<matthias.baesken at sap.com>; 'hotspot-
>> dev at openjdk.java.net'<hotspot-dev at openjdk.java.net>; hotspot-jfr-
>> dev at openjdk.java.net
>> Subject: Re: RFR [XS]: 8229370: make
>> jdk/jfr/event/runtime/TestNetworkUtilizationEvent.java more stable
>>
>> Hi Matthias,
>>
>> On 27/08/2019 5:41 pm, Baesken, Matthias wrote:
>>> Hello, any reviews for this small change ?
>> I missed the initial request - sorry.
>>
>> Seems we have a double up of effort here as we also have JDK-8228990 for
>> the exact same problem that we see on some of our test machines.
>>
>> Our analysis suggests that this test often passes by accident due to
>> incidental activity on the real network interface when the logic
>> intended to generate that activity (the packet sent to 10.0.0.0:12345)
>> actually had no affect (unreachable address). If there is no incidental
>> network activity then the real network interface is not seen and so the
>> test fails.
>>
>> David
>>
>>> Thanks , Matthias
>>>
>>> From: Baesken, Matthias
>>> Sent: Montag, 12. August 2019 14:33
>>> To: 'hotspot-dev at openjdk.java.net'<hotspot-dev at openjdk.java.net>;
>> 'hotspot-jfr-dev at openjdk.java.net'<hotspot-jfr-dev at openjdk.java.net>
>>> Subject: RFR [XS]: 8229370: make
>> jdk/jfr/event/runtime/TestNetworkUtilizationEvent.java more stable
>>> Hello, please review this small test enhancement.
>>>
>>> We noticed that on some of our Linux machines  (SLES12 based)   the
>> TestNetworkUtilizationEvent.java test reported just 1 interface
>>> (the test  TestNetworkUtilizationEvent.java  expects more than 1 on Linux).
>>>
>>> Looking into the HS code , os_perf_linux.cpp collects the interfaces +
>> additional information about bytes read/written  (by looking at
>> /sys/class/net/eth<X>/statistics/<countername>   )
>>> and this info is given to JFR .
>>>
>>> However it seems to need (at least on some machines / setups) more
>> packet send operations / potential  retries to really  get counter updates
>> (and without updates in the counters,   no interfaces are found).
>>> So I adjusted the test accordingly.
>>>
>>>
>>> Bug/webrev :
>>>
>>> https://bugs.openjdk.java.net/browse/JDK-8229370
>>>
>>> http://cr.openjdk.java.net/~mbaesken/webrevs/8229370.0/
>>>
>>>
>>> Best regards, Matthias
>>>