RFR[10] 8190984 : tools/launcher/TestXcheckJNIWarnings.java WARNING was found in the output

[mandy chung]

How do we pick the value 50?  The JNI local refs are deleted in some 
cases and it's unclear how 50 is computed.  What if new properties are 
added in the future?

Mandy

On 12/12/17 4:00 PM, David Holmes wrote:
> Reviewed! :)
>
> Thanks Brent!
>
> I guess I can push these both now.
>
> David
>
> On 13/12/2017 9:38 AM, Brent Christian wrote:
>> Hi,
>>
>> Please review this small change to the System.initProperties() native 
>> method.
>>
>> The tools/launcher/TestXcheckJNIWarnings.java has begun to fail due 
>> to this warning being issued:
>>
>> WARNING: JNI local refs: 41, exceeds capacity: 40
>>          at java.lang.System.initProperties(java.base/Native Method)
>>          at java.lang.System.initPhase1(java.base/System.java:1943)
>>
>> This has only been seen on solaris-sparc with LANG=C.  In fact, the 
>> warning can also be seen with a simple HelloWorld program, run with 
>> -Xcheck:jni.  This started happening as of JDK-8043224 ("-Xcheck:jni 
>> improvements to exception checking and excessive local refs").
>>
>> The following change should be made to prevent the warning:
>>
>> diff -r ed1bb7743b3e src/java.base/share/native/libjava/System.c
>> --- a/src/java.base/share/native/libjava/System.c    Tue Dec 12 
>> 19:05:02 2017 +0100
>> +++ b/src/java.base/share/native/libjava/System.c    Tue Dec 12 
>> 15:21:03 2017 -0800
>> @@ -186,6 +186,9 @@
>>       jobject ret = NULL;
>>       jstring jVMVal = NULL;
>>
>> +    if ((*env)->EnsureLocalCapacity(env, 50) < 0) {
>> +        return NULL;
>> +    }
>>       sprops = GetJavaProperties(env);
>>       CHECK_NULL_RETURN(sprops, NULL);
>>
>>
>> Of note: an additional change is needed, to EnsureLocalCapacity itself:
>>
>> 8193222 : EnsureLocalCapacity() should maintain capacity requests 
>> through multiple calls
>>
>> That fix has already been proposed and reviewed.
>> These two fixes should be pushed together via hs, which David has 
>> kindly offered to do, pending code review approval of my change here.
>>
>> Thanks,
>> -Brent
>>