RFR [XS] 8207832 - ClhsdbCDSCore.java failed with "Couldn't find core file location"

[Ioi Lam]

On 8/15/18 6:14 PM, David Holmes wrote:
> Hi Ioi,
>
> On 15/08/2018 9:50 AM, Ioi Lam wrote:
>> Please review this simple fix.
>>
>>      https://bugs.openjdk.java.net/browse/JDK-8207832
>> http://cr.openjdk.java.net/~iklam/jdk12/8207832_ClhsdbCDSCore_file_location.v01/ 
>>
>>
>> On Linux, the core file location can be controlled via 
>> /proc/sys/kernel/core_pattern.
>> It could have various patterns such as
>>
>>     core
>>     core.%p
>>     core.%p.something
>>     /tmp/core
>>     /tmp/core.%p
>>     /tmp/core.%p.something
>
> It could also have numerous other % variables that the test probably 
> chokes on:
>
> https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
>
> I'm not sure the right fix here is not to just make the test more 
> resilient given the possible the pattern replacements.
>
Hi David,

If we want to handle all cases, we need to implement what kernel.txt 
says (if only I knew what "%g gid (in initial user namespace)" means). 
And it would be better to implement that in the VM, so it will benefit 
all readers of hs_err files, instead of doing that in this test to 
benefit this test only.

For now, I am content to just handle the %p case, as that's how our 
testing hosts are configured. Even for just %p it's hard to do it in the 
test, as you would need to find the child process's pid.

If you don't have any objection, I'' push the patch as is. Can I count 
you as a reviewer?

Thanks
- Ioi

> But doing the %p expansion doesn't seem to hurt.
>
> Thanks,
> David
>
>> I've tested the fix with all the above patterns, and the %p is correctly
>> replaced by the process ID.
>>
>> Note that the pattern can also be more complex, starting with a 
>> piping character ("|").
>> I have not touched that part of the code, since it doesn't seem to 
>> affect our internal
>> test infrastructure.
>>
>> I also instrumented ClhsdbCDSCore.java so we can more easily diagnose 
>> such problems
>> in the future.
>>
>> For more info, see 
>> https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
>>
>> I'll validate with hs tiers 1/2/3/4.
>>
>> Thanks
>> - Ioi
>>
>>