RFR : 8182672: Java 8u121 on Linux intermittently returns null for MAC address

[Seán Coffey]

Thanks to Christoph, Vyom and Mark for the reviews.

I've improved the testcase as per feedback. Hope this meets all requests :

http://cr.openjdk.java.net/~coffeys/webrev.8182672.jdk10.v2/webrev/

Regards,
Sean.

On 22/06/17 22:36, Langer, Christoph wrote:
> Hi Sean,
>
> I played with it a bit more and now really understand Vyoms observation. So, what he sees is not the original concurrency issue but he encounters a SocketException on some interface, where this is supposed to occur upon calling getHardwareAddress().
>
> So, to enable the testcase to run robustly on any platform, any hardware and any network configuration, I suggest to modify the test like this:
>
> 1. In main, enumerate all interfaces once
> 2. Iterate over all interfaces, exlude loopback and see if a single call to getHardwareAddress() won't yield null or an Exception.
> 3. For each interface where a valid mac address could be obtained once, start the executor threads to stress getHardwareAddress() in parallel, e.g. like 5 threads doing it 100 times in parallel. I would also suggest to use per thread counters instead of one global 'count' as we have right now.
>
> Furthermore, the test output could be improved a bit, e.g. when it comes to an exception, the thread name could be mentioned, too.
>
> Best regards
> Christoph
>
>> -----Original Message-----
>> From: net-dev [mailto:net-dev-bounces at openjdk.java.net] On Behalf Of
>> Seán Coffey
>> Sent: Donnerstag, 22. Juni 2017 20:17
>> To: Vyom Tewari <vyom.tewari at oracle.com>; net-dev <net-
>> dev at openjdk.java.net>
>> Subject: Re: RFR : 8182672: Java 8u121 on Linux intermittently returns null for
>> MAC address
>>
>> Hi Vyom,
>>
>> thanks for testing. Null is a valid value for some interfaces. I've
>> excluded the loopback interface from being testing. Perhaps there's
>> other issues at play here.  We know that getHardwareAddress() can throw
>> SocketException if I/O fails. For this particular scenario we're not
>> interested in that and perhaps that can be ignored.
>>
>> I'll take another look.
>>
>> regards,
>> Sean.
>>
>> On 22/06/2017 18:50, Vyom Tewari wrote:
>>> Hi Sean,
>>>
>>> with your patch as well your test case is failing on my
>>> laptop(Ubuntu16.04), when i tried to run  on jdk8 i am getting below
>>> error.
>>>
>>> java.net.SocketException: No such device (ioctl(SIOCGIFHWADDR) failed)
>>>      at java.net.NetworkInterface.getMacAddr0(Native Method)
>>>      at
>>>
>> java.net.NetworkInterface.getHardwareAddress(NetworkInterface.java:457
>> )
>>>      at com.java.test.GetMacAddress.run(GetMacAddress.java:66)
>>>      at
>>>
>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.jav
>> a:1142)
>>>      at
>>>
>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.ja
>> va:617)
>>>      at java.lang.Thread.run(Thread.java:745)
>>> java.net.SocketException: No such device (ioctl(SIOCGIFHWADDR) failed)
>>>      at java.net.NetworkInterface.getMacAddr0(Native Method)
>>>      at
>>>
>> java.net.NetworkInterface.getHardwareAddress(NetworkInterface.java:457
>> )
>>>      at com.java.test.GetMacAddress.run(GetMacAddress.java:66)
>>>      at
>>>
>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.jav
>> a:1142)
>>>      at
>>>
>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.ja
>> va:617)
>>>      at java.lang.Thread.run(Thread.java:745)
>>> Exception in thread "main" java.lang.RuntimeException: Failed
>>>      at com.java.test.GetMacAddress.main(GetMacAddress.java:96)
>>> mac id is null for interface cscotun0- Thread0
>>> Testing: cscotun0
>>> mac id is null for interface cscotun0- Thread3
>>> Testing: cscotun0
>>>
>>> Thanks,
>>>
>>> Vyom
>>>
>>>
>>> On Thursday 22 June 2017 09:59 PM, Seán Coffey wrote:
>>>> JDK 10 fix required to correct a race issue in NetworkInterface. I
>>>> don't believe the ifreq struct needs to be static in any case. New
>>>> auto unit testcase also. I propose to skip this fix for JDK 9 and fix
>>>> in an update release for that family. I also plan to port this to
>>>> jdk8u-dev.
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8182672
>>>> webrev :
>>>> http://cr.openjdk.java.net/~coffeys/webrev.8182672.jdk10/webrev/
>>>>
>>>> regards,
>>>> Sean.