RFR (L): 8024545: make develop and notproduct flag values available in product builds

[Christian Thalinger]

On Sep 11, 2013, at 5:34 PM, David Holmes <david.holmes at oracle.com> wrote:

> Hi Chris,
> 
> There seems to be an awful lot "infrastructure" work needed to make something that sounds simple happen. :( All the changes to the scoping and the set/get methods tends to obscure the core change. My only suggestion here is that the "set" methods could perhaps factor this:
> 
> +   if (is_constant_in_binary()) {
> +     fatal(err_msg("flag is constant: %s", _name));
> 
> into a check_writable() method so that it isn't duplicated so much.

Good point.  I made that change:

http://cr.openjdk.java.net/~twisti/8024545/webrev/src/share/vm/runtime/globals.cpp.udiff.html

> 
> I also wonder whether a ConstFlag sub/superclass would simplify this at all?

Maybe it would but then we need more infrastructure to read the additional entries.  Might be a wash.  SA only knows about offsets in structs and the flags array is statically defined.

> 
> That aside I'm curious why the minimal VM size change is only 22K when client is 32K?

The 32-bit product build also contains the server compiler.

-- Chris

> 
> Thanks,
> David
> 
> On 11/09/2013 10:56 AM, Christian Thalinger wrote:
>> http://cr.openjdk.java.net/~twisti/8024545/webrev/
>> 
>> 8024545: make develop and notproduct flag values available in product builds
>> Reviewed-by:
>> 
>> Right now the internal flag table only contains flags which are defined in a product build. This does not include develop and notproduct flags. Sometimes it is useful to have access to these values for post-mortem core file analysis or to read these values for compiler settings for a Java-based compiler.
>> 
>> This change enables develop and notproduct flag values to be read by the serviceability agent. The binary size is increased by 42k for a 64-bit product build and by 32k for a 32-bit product build.
>> 
>> Before:
>> 
>> $ java -cp /java/re/jdk/8/latest/binaries/linux-x64/lib/sa-jdi.jar sun.jvm.hotspot.CLHSDB 9399
>> Attaching to process 9399, please wait...
>> hsdb> flags -nd
>> InitialHeapSize = 495006528 5
>> MaxHeapSize = 7920943104 5
>> UseCompressedKlassPointers = true 5
>> UseCompressedOops = true 5
>> UseParallelGC = true 5
>> hsdb> flags InlineMathNatives
>> Couldn't find flag: InlineMathNatives
>> 
>> After:
>> 
>> $ java -cp $JAVA_HOME/lib/sa-jdi.jar sun.jvm.hotspot.CLHSDB 3726
>> Attaching to process 3726, please wait...
>> hsdb> flags -nd
>> InitialHeapSize = 495006528 5
>> MaxHeapSize = 7920943104 5
>> UseCompressedKlassPointers = true 5
>> UseCompressedOops = true 5
>> UseParallelGC = true 5
>> hsdb> flags InlineMathNatives
>> InlineMathNatives = true 0
>> 
>> This patch has one behavioral difference; when printing flags with e.g. PrintFlagsFinal in a debug build it prints "develop" for develop flags:
>> 
>>     uintx AdaptiveSizePolicyGCTimeLimitThreshold    = 5               {develop}
>> 
>> The output for product builds is unchanged.
>>