[9] RFR(XXS): 8036091: compiler/membars/DekkerTest.java fails with -XX:CICompilerCount=1

[Albert]

Hi Roland,

thanks for your feedback.

Silently using 2 instead of 1 compiler thread when tiered is enabled and 
-XX:CICompilerCount=1
was the default behavior before JDK-8034775. I worked on JDK-8034775 and 
back than it occurred
to me that it is strange that the JVM silently 'overrules' an explicit 
command given by the user
(namely that he/she wants to use only 1 compiler thread).

Since the tests starts with -Xbatch and hence background compilation is 
disabled, I do not see how
more compiler threads can fail the test. Also, the original bug 
reproduces easily with more than 1
compiler thread.

Best,
Albert


On 03/03/2014 11:04 AM, Roland Westrelin wrote:
> Hi Albert,
>
>> Problem:
>> JDK-8034775 changed the minimum number of compiler threads for tiered compilation to 2, since each compiler (C1 and C2) requires a separate compiler thread. The test is started with -XX:CICompilerCount=1, which is illegal after JDK-8034775.
>>
>> Solution:
>> Remove -XX:CICompilerCount=1
> But then if we run with tiered off, C2 will have more than 1 compiler thread which is not what the test wants for some reason. Maybe if tiered is on CICompilerCount=1 should make the VM silently use 1 thread per compilers?
>
> Roland.