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

[sangheon.kim]

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
>>
>