Re: Java version used by Jpl (Prolog to Java)

On 20/03/2014, at 16:56, Paulo Moura <[email protected]> wrote:

> 
> On 20/03/2014, at 16:15, Jan Wielemaker <[email protected]> wrote:
> 
>> On 03/20/2014 04:01 PM, Paulo Moura wrote:
>>> 
>>> On 19/03/2014, at 00:03, Sergio Castro <[email protected]> wrote:
>>> 
>>>> I have just realized that the Java version used by JPL (Prolog side) is not the one configured by default.
>>>> 
>>>> My installed Java version is 7, as verified with:
>>>> 
>>>> $ java -version
>>>> java version "1.7.0_51"
>>>> Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
>>>> Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)
>>>> 
>>>> Also, the JAVA_HOME environment var is properly set.
>>>> 
>>>> However, if I execute this query in swi:
>>>> 
>>>> ?- jpl_call( class([java,lang],['System']), 'getProperty', ['java.version'], V).
>>>> V = '1.6.0_65'.
>>>> 
>>>> 
>>>> I see that it is using Java 6 instead of 7. How could I fix it so it will use the default java installation ?
>>> 
>>> I can reproduce the problem with SWI-Prolog 7.1.10. But the strange thing is that in the "packages/jpl/config.log" file I have:
>>> 
>>> JAR='/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/jar'
>>> JAVA='/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/java'
>>> JAVAC='/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/javac'
>>> JAVACFLAGS='-source 1.4 -target 1.4'
>>> JAVADOC='/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/javadoc'
>>> JAVALIBS='-Wl,-framework,JavaVM'
>>> JAVA_HOME='/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home'
>>> JAVA_LIBRARY_PATH=''
>>> JAVA_PRELOAD=''
>>> JPLCFLAGS='-I'\''/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/include'\'' -I'\''/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/include/darwin'\'''
>>> 
>>> Nevertheless, I also get:
>>> 
>>> ?- jpl:jpl_call('java.lang.System',getProperty,['java.version'],_G1413)
>>> V = '1.6.0_65'.
>>> 
>>> So, it seems that JPL is built using Java 7 but at runtime it starts (the Apple provided and installed under /System) Java 6.
>> 
>> I guess the final VM is decided by what is linked to libjpl.dylib.
> 
> It seems so.
> 
>> You can find that using
>> 
>> 	otool -L libjpl.dylib
> 
> $ otool -L libjpl.dylib
> libjpl.dylib:
> 	/System/Library/Frameworks/JavaVM.framework/Versions/A/JavaVM (compatibility version 1.0.0, current version 1.0.0)
> 	/Users/pmoura/lib/swipl-7.1.10/lib/x86_64-darwin13.1.0/libswipl.dylib (compatibility version 0.0.0, current version 7.1.10)
> 	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)
> 	/opt/local/lib/libgcc/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
> 
>> You can change that using
>> 
>> 	install_name_tool -change old new libjpl.dylib
>> 
>> Hope this helps (otherwise you need a real Apple guru).
> 
> I tried it but I didn't find any libjvm.dylib library on the Java 7 installation. It may go by a different name. Tried to link instead to libjava.dylib but it didn't work.

Found it at lib/server:

/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/jre/lib/server/libjvm.dylib

Doing as you suggested works:

$ install_name_tool -change /System/Library/Frameworks/JavaVM.framework/Versions/A/JavaVM /Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/jre/lib/server/libjvm.dylib libjpl.dylib

?- jpl:jpl_call('java.lang.System',getProperty,['java.version'],_).
V = '1.7.0_51'.

Also got it working with the current beta of Java 8:

$ install_name_tool -change /System/Library/Frameworks/JavaVM.framework/Versions/A/JavaVM /Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home/jre/lib/server/libjvm.dylib libjpl.dylib

Cheers,

Paulo

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Paulo Moura
Logtalk developer

Email: <mailto:[email protected]>
Web:   <http://logtalk.org/>
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