Nashorn in the future (English)

Nashorn intheFuture

Oracle Corporation JapanFusion Middleware Business UnitNISHIKAWA, Akihiro8, April, 2015

Copyright©2015, Oracleand/oritsaffiliates.Allrightsreserved.|


SafeHarborStatementThefollowingisintendedtooutlineourgeneralproductdirection.Itisintendedforinformationpurposesonly,andmaynotbeincorporatedintoanycontract.Itisnotacommitmenttodeliveranymaterial,code,orfunctionality,andshouldnotberelieduponinmakingpurchasingdecisions.Thedevelopment,release,andtimingofanyfeaturesorfunctionalitydescribedforOracle’sproductsremainsatthesolediscretionofOracle.

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Agenda

What'sNashorn?

8u20

8u40

Inthefuture...

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4

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What’sNashorn?

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Nashorn

• ReplacementforRhino– Forimprovingsecurityandperformance

• ProofofConceptforInvokeDynamic (JSR-292)

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JavaScriptEngineintroducedinJava8 (JEP174)


Nashorn

• ECMAScript-262Edition5.1

• javax.script (JSR223)API

• InteractionbetweenJavaandJavaScript

• Commandlinetool:jjs

JavaScriptEngineintroducedinJava8 (JEP174)

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Getstarted!• jjs– HelloWorld– LambdaExpression,Stream

• Scripting– Usertheoptionof“-scripting”– CallWebAPI

• JavaFX– Usertheoptionof“–fx”–WebView

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Lambda ExpressioninNashorn// Javaarray.stream().sorted(Comparator.naturalOrder()).forEach( t -> sortedArray.add(t) );

// Nashornarray.stream().sorted(Comparator.naturalOrder()).forEach(function(t) sortedArray.add(t));

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CallfromJava(1/3)ScriptEngineManager manager =

new ScriptEngineManager();ScriptEngine engine =

manager.getEngineByName("nashorn");// Evaluationengine.eval("print('hello world')"); // hello worldengine.eval(new FileReader(“hello.js”)); // hello.js

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CallfromJava(2/3)

engine.eval("function hello(name){print('Hello, ' + name); }");

Invocable inv=(Invocable)engine;

// Hello, TaroObject obj= inv.invokeFunction("hello","Taro");

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InvokeJavaScriptfunction


CallfromJava(3/3)

engine.eval("function run(){print('run() called');

}");Invocable inv =(Invocable)engine;Runnable r=inv.getInterface(Runnable.class);Thread th=new Threads(r);th.start();th.join();

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ImplementinterfacewithScriptfunction


8u20

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8u20

• Focusedonsecurityimprovementandenhancementofunderlyingplatform– JIT– JDK

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ReleasedinAugust,2014


Replace“const”with“var”

• Default:false

• Itmightretireinthefuturesince8u40supportsconst.

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--const-as-var=true|false


ForbidaccessJavaPackagesandClassesfromJavaScript

• Default:false

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--no-java=true|false (-nj)


ForbidusingsyntaxagainstECMAScriptstandard

• AbletouseAPIExtensionsuchasJava.type• Disabledwhenusing-scripting

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--no-syntax-extensions (-nse)


#sourceURL and @sourceURL

• Fordebuging use– //# sourceURL=myScript.js– @sourceURL=myScript.js

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JDK-8032068:implement@sourceURL and#sourceURL directives


ClassCache

• Originallycompilationisrequiredevenifinvokingprevioususedscript.• Since8u20,previousevaluatedscriptisstoredincacheforreuse.

• Example– fromJavaengine.eval(new URLReader(myScriptURL));– fromJavaScriptload(url);

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JDK-8021350:Sharescriptclassesbetweenthreads/globals withincontext


8u40

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8u40

• Performanceimprovement–Optimistictyping(JEP196)– CodePersistence(JEP194)

• Security– ClassFilter(JEP202)

• PartialsupportforECMAScript6– Lexical-scopedvariablesandconstantdefinition(JEP203)

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ImplementedJEP


JEP196:OptimisticTyping

• Typeinferenceatcompilation(notatruntime)– Assumespecifictypeusedatoperationandmanipulationofarrayindex– Iftypeinferenceiswrong,fallbackandrecompilewithmorepessimisticassumption

• --optimistic-types=true|false (-ot)– Default:false

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ForgeneratingbytecodelikeJava

int long

double

Object


JEP196:OptimisticTyping

• nashorn.typeInfo.maxFiles–Maximum#offilestocachetypeinformation– if0 issettothisproperty,cachingisdisabled.

• nashorn.typeInfo.cacheDir– Directorywherefilesstoringcachedtypeinformationexist.•Windows: ${java.io.tmpdir}¥com.oracle.java.NashornTypeInfo• LinuxandSolaris: ~/.cache/com.oracle.java.NashornTypeInfo•MacOSX: ~/Library/Caches/com.oracle.java.NashornTypeInfo

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Cachingresultoftypeinference


JEP194:CodePersistence

• Cachecodeforre-usewithinthesameprocess.• Thishelpssmallermemoryusageandshorterstartuptime.

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Performanceimprovementwithcachingcode



• --class-cache-size=50 (-ccs)– Classcachesizeperglobalscope– Default:50

• --persistent-code-cache=true|false (-pcc)– Specifieswhetherornotoptimistictypeinformationaswellascompiledscriptsarepersistedtodisk– Default:false

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Performanceimprovementwithcachingcode



• Whereiscodecachestored?– Default:WheninvokingJavaScript,directorynamednashorn_code_cache iscreatedandcacheddataarestored.– Directorynameisconfigurable.• nashorn.persistent.code.cache

• Filestoredcacheddatacontainsnotonlyclassbytecodebutalsovariousmetadata.

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Optimistictypeinformationisalsocachedtodisk


Lazycompilation

• Compilemethodsondemand• Default:true– Before8u40,defaultsettingwasfalse duetoexperimentaloption.

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--lazy-compilation=true|false


JEP202:ClassFilter

• JEP202:Nashorn ClassFilterhttps://bugs.openjdk.java.net/browse/JDK-8043717

• Impementation isrequiredinJavaapplicationwhichusesJavaScript.– jdk.nashorn.api.scripting.ClassFilter

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ForbidaccessingJavaclassesfromJavaScript


ClassFilter

// restrcting access to java.io.Fileimport jdk.nashorn.api.scripting.ClassFilter;

class MyFilter implements ClassFilter {@Overridepublic boolean exposeToScripts(String s) {

if (s.compareTo("java.io.File") == 0) return false;return true;

}}

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Implementationexample


PartialsupportforECMAScript6

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JEP203:Lexically-scopedvariableandconstantdeclarations

• --language=es5|es6– Default:es5– --language=es6 ismandatorywhenusingconst andlet

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Supportforkeyword“let”and“const”


// letlet a=2;

function f(x) {// a=2if(x) {

let a=42;}// a is still equal to 2

}

// varvar a=2;

function f(x) {// a is not undefinedif(x) {

var a=42;}// depending upon x, a is

equal to 42 or undefined}

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let andvar


// 1) Syntax errorfunction f(x) {

const b=1;// Unable to assignb = 99;

}

// 2) Scope #1function f(x) {

const b=1;var z=b+1; //z=2

}//b is undefinedvar y=b+1;

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// 3) Scope #2function f(x) {

const b=1;var z =b+1; //z=2

}//Able to declare bconst b = 10;

const

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ServerSideJavaScript

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ServersideJavaScript...• Node.jscompatibleframeworkrunningonJVM– Nodyn• Vert.x+Dyn.JS+Netty

– Trieme• byApigee

• ReactiveProgramming– RxJS– React.JS

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https://blogs.oracle.com/theaquarium/entry/project_avatar_updateAvatar...


Inthefuture...

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IntheFuture

• Improvewithsteadywork– Shorterwarmuptime– Enhancement/improvementofOptimisticTypingandCodePersistence

• Java9– Fullysuport forECMAScript6(Java9)– ParserAPIforNashorn (JEP236)– JavaFlightRecorder• JavaScriptProfiler• TagforNashorn

...etc37

Java8u60,9,and...


Improvewithsteadywork

• ImproveperformancewhenparsingJSON– PoorperformancewhenhandlingsmallJSONobjectsusingPropertyHashMap#findElement

• Re-writejdk.nashorn.internal.parser.JSONParser

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Forexample...


JavaFlightRecorder

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JEP236:ParserAPIforNashorn

• Objective– ParserAPIforrepresentingECMAScriptcodeasAST– Visitorpattern– Introducedtohideinternalimplementationpackage (jdk.nashorn.internal.ir)

• Notice– NotscriptlevelAPIbutJavaAPI

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PublicAPIforECMAScript AST


JEP236:ParserAPIforNashorn

• AvailableafterJDK9b55• JavaDoc– https://bugs.openjdk.java.net/browse/JDK-8048176

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jdk.nashorn.api.tree

Copyright©2015,Oracleand/oritsaffiliates.Allrightsreserved.|

Takeaway

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Keytakeaway• Manyfeaturesandimprovementhavebeenintroducedto8u20and8u40.

• Nashorn isbeingimproveddaybyday,ofcourse.

• Pleasegiveyourfeedbacktodevelopmentteam!

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Nashorn Project

• Nashorn MailingList– [email protected]

• Nashorn Wiki– https://wiki.openjdk.java.net/display/Nashorn/Main

• DEVELOPER_README– http://hg.openjdk.java.net/jdk8u/jdk8u-dev/nashorn/file/tip/docs/DEVELOPER_README

• Nashorn - JavaScriptfortheJVM– http://blogs.oracle.com/nashorn/

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http://openjdk.java.net/projects/nashorn/


SafeHarborStatementTheprecedingisintendedtooutlineourgeneralproductdirection.Itisintendedforinformationpurposesonly,andmaynotbeincorporatedintoanycontract.Itisnotacommitmenttodeliveranymaterial,code,orfunctionality,andshouldnotberelieduponinmakingpurchasingdecisions.Thedevelopment,release,andtimingofanyfeaturesorfunctionalitydescribedforOracle’sproductsremainsatthesolediscretionofOracle.

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Copyright©2015, Oracleand/oritsaffiliates.Allrightsreserved.| 46


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Nashorn in the future (English)