RFR (S): 8139801: Error message from validation check has wrong order on Windows

[Chris Plummer]

Hi Sangheon,

Thanks for doing this. A few comments/suggestions:

I don't think the #ifdef __WIN32__ should be needed. Although we are 
doing the fflush mainly to address issues we only currently see on 
win32, there's no reason why the fflush can't be done on all platforms. 
I think that will help keep the code cleaner.

In jni.cpp, is there a reason not to flush unconditionally (outside the 
if/else)?

Please make sure your commit comment references all 3 CRs this fix is 
addressing:

8139374 TlabSize.java argument test fails
8078328 AppCDS jtreg test result missing expected error message in stderr
8139801 Error message from validation check has wrong order on Windows

I'm not a "R"eviewer.

thanks,

Chris

On 10/20/15 3:03 PM, sangheon.kim wrote:
> Hi all,
>
> Initially I only tested validation error messages but later I noticed 
> that other error messages also have same problem on Windows. (thanks 
> to Chris Plummer for the discussion)
>
> When we fail to create VM, we end with 1) returning to the caller or 
> 2) call vm_abort().
> For the 1) case, all error messages have wrong order on Windows.
>
> eg) an error message on Windows. (this is NG)
> $ java -XX:VMOptionsFile=foo -XX:VMOptionsFile=bar
> Error: Could not create the Java Virtual Machine.
> Error: A fatal exception has occurred. Program will exit.
> Only one VM Options file is supported on the command line  <- this 
> should be printed first.
>
> We can see easily this wrong order on Windows but the problem is 
> there's no guarantee that 'stdout/stderr' will be flushed on that 
> situation.
>
> As a solution I added fflush(stdout) and fflush(stderr) for above two 
> cases.
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8139801
> Webrev: http://cr.openjdk.java.net/%7Esangheki/8139801/webrev.01/
> Testing: JPRT
>
> Thanks,
> Sangheon
>
>
> On 10/19/2015 01:00 PM, sangheon.kim wrote:
>> Hi all again,
>>
>> Let me cancel this patch as this kind of problem seems general on 
>> Windows.
>>
>> Thanks,
>> Sangheon
>>
>>
>> On 10/19/2015 08:56 AM, sangheon.kim wrote:
>>> Hi all,
>>>
>>> Can I get some reviews for this change of adding 'fflush()' on 
>>> validation message print?
>>>
>>> The order of 'validation error message' and 'vm exit message' is 
>>> wrong on Windows.
>>> - Windows is buffering the validation error message which is sent to 
>>> 'stderr'.
>>> - 'stderr' from 'jvm.dll' is flushed later than 'stderr' from the 
>>> caller of 'jvm.dll'.
>>>
>>> eg) Expected message order (all other platforms except Windows)
>>> $ java -XX:MinTLABSize=1 -version
>>> 1) MinTLABSize (1) must be greater than or equal to reserved area in 
>>> TLAB (16)
>>> 2) Error: Could not create the Java Virtual Machine. \n Error: A 
>>> fatal exception has occurred. Program will exit.
>>>
>>> On Windows:
>>> $ java -XX:MinTLABSize=1 -version
>>> 2) Error: Could not create the Java Virtual Machine. \n Error: A 
>>> fatal exception has occurred. Program will exit.
>>> 1) MinTLABSize (1) must be greater than or equal to reserved area in 
>>> TLAB (16)
>>>
>>> As a solution, I added 'fflush()' on print function of validation 
>>> check (CommandLineError::print).
>>> And any other functions that are printing to 'stderr' would have 
>>> similar fix for Windows.
>>>
>>> CR: https://bugs.openjdk.java.net/browse/JDK-8139801
>>> Webrev: http://cr.openjdk.java.net/~sangheki/8139801/webrev.00/
>>> Testing: JPRT
>>>
>>> Thanks,
>>> Sangheon
>>>
>>
>