Rhino和对javax.script.ScriptEngine的并发访问
我通过Rhino和对javax.script.ScriptEngine的并发访问,java,javascript,rhino,Java,Javascript,Rhino,我通过javax.scriptAPI使用Rhino 1.6r2。我知道Rhino引擎声称“引擎实现在内部是线程安全的，脚本可以并发执行，尽管脚本在一个线程上执行的效果可能对其他线程上的脚本可见。” 我想知道的是，在什么样的确切条件下，一个脚本执行的效果对另一个脚本执行是可见的？在我的代码中，我有时会重复使用ScriptEngine对象，但每次执行时，我都会创建一个新的SimpleBindings，并将其传递给eval（String，Bindings）。有了这种安排，内部状态是否有可能从一个执行泄
javax.scriptScriptEngineSimpleBindingseval（String，Bindings）是的，JSR223没有指定脚本语言中的变量应该如何与给定的
绑定绑定。因此，实现者完全有可能选择在引擎实例中存储全局范围变量，并在评估脚本时重用它，即使给定不同的绑定
例如，JRuby的JSR223绑定有一种模式是以这种方式工作的
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleScriptContext;
public class Jsr223Binding {
private Jsr223Binding() throws ScriptException {
System.setProperty("org.jruby.embed.localvariable.behavior", "transient");
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("jruby");
ScriptContext ctx1 = new SimpleScriptContext();
ScriptContext ctx2 = new SimpleScriptContext();
engine.eval("$foo = 5\nputs $foo", ctx1);
engine.eval("puts $foo", ctx2);
}
public static void main(String[] args) throws ScriptException {
new Jsr223Binding();
}
}
script包是线程安全的，但如果您的脚本不是线程安全的，则可能会出现并发问题。
脚本中的全局变量对所有线程都可见。因此，避免在javascript函数中使用全局变量
我现在遇到了这个问题。我的javascript如下所示：
function run(){
regex = 0;
regex += 1;
return regex;
}
我在线程池中运行它（4）10000次，并打印结果
for (int i = 0; i <= 10000; i++){
executor.submit(new Runnable() {
@Override
public void run() {
try {
Double result = (Double) invocable.invokeFunction("run");
System.out.println(result);
} catch (Exception e) {}
}
});
}
我修改了答案，以表明如果在eval（）函数中指定上下文，rhino脚本引擎的执行是完全线程安全的。此示例同时从5个不同线程调用javascript函数100次：
package samplethread;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleScriptContext;
public class JSRunner {
private static final ScriptEngine engine;
private static final ScriptEngineManager manager;
private static final String script = "function fibonacci(num){\r\n" +
" var a = 1, b = 0, temp;\r\n" +
"\r\n" +
" while (num >= 0){\r\n" +
" temp = a;\r\n" +
" a = a + b;\r\n" +
" b = temp;\r\n" +
" num--;\r\n" +
" }\r\n" +
"\r\n" +
" return b;\r\n" +
"} \r\n" +
"var out = java.lang.System.out;\n" +
"n = 1;" +
"while( n <= 100 ) {" +
" out.println(java.lang.Thread.currentThread().getName() +':'+ 'FIB('+ n +') = ' + fibonacci(n));" +
" n++;" +
" if (java.lang.Thread.interrupted()) {" +
" out.println('JS: Interrupted::'+Date.now());" +
" break;" +
" }" +
"}\n";
static {
manager = new ScriptEngineManager();
engine = manager.getEngineByName("JavaScript");
}
public static void main(final String... args) throws Exception {
for(int i = 0;i<5;i++) {
try {
final Bindings b = engine.createBindings();
final SimpleScriptContext sc = new SimpleScriptContext();
sc.setBindings(b, ScriptContext.ENGINE_SCOPE);
execWithFuture(engine, script,sc);
}
catch(Exception e) {
e.printStackTrace();
}
}
}
private static void execWithFuture(final ScriptEngine engine, final String script,final ScriptContext sc) throws Exception {
System.out.println("Java: Submitting script eval to thread pool...");
ExecutorService single = Executors.newSingleThreadExecutor();
Callable<String> c = new Callable<String>() {
public String call() throws Exception {
String result = null;
try {
engine.eval(script,sc);
} catch (ScriptException e) {
result = e.getMessage();
}
return result;
}
};
single.submit(c);
single.shutdown();
System.out.println("Java: ...submitted.");
}
}
package-samplethread；
导入java.util.concurrent.Callable；
导入java.util.concurrent.ExecutorService；
导入java.util.concurrent.Executors；
导入java.util.concurrent.Future；
导入javax.script.Bindings；
导入javax.script.ScriptContext；
导入javax.script.ScriptEngine；
导入javax.script.ScriptEngineManager；
导入javax.script.ScriptException；
导入javax.script.SimpleScriptContext；
公共类JSRunner{
私有静态脚本引擎；
私有静态最终脚本引擎管理器；
private static final String script=“函数fibonacci（num）{\r\n”+
变量a=1，b=0，临时；\r\n“+
“\r\n”+
“while（num>=0）{\r\n”+
“temp=a；\r\n”+
“a=a+b；\r\n”+
“b=temp；\r\n”+
“num——；\r\n”+
“}\r\n”+
“\r\n”+
“返回b；\r\n”+
“}\r\n”+
“var out=java.lang.System.out；\n”+
“n=1；”+
“一会儿（n你是在绑定同一个对象吗？如果我绑定同一个对象进行多次执行，那么显然所有人都可以看到。但不，我没有这么做。那么你到底想弄清楚什么？如果你对不同的绑定对象使用不同的绑定，你还关心哪些状态？@wort-I是t暗示更多由脚本创建或修改的状态，而不是从Java传递到脚本中。如果我在脚本中声明一个全局变量，该变量的范围是什么？如果我修改某个内置全局变量会发生什么？这些是由javax.script API指定的，还是由引擎实现者指定的？这是您正在寻找的吗对于？您所说的根本不是真的。如果为同一脚本引擎实例创建单独的脚本上下文，并指定适当的范围（引擎范围），则不会出现此问题。
package samplethread;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleScriptContext;
public class JSRunner {
private static final ScriptEngine engine;
private static final ScriptEngineManager manager;
private static final String script = "function fibonacci(num){\r\n" +
" var a = 1, b = 0, temp;\r\n" +
"\r\n" +
" while (num >= 0){\r\n" +
" temp = a;\r\n" +
" a = a + b;\r\n" +
" b = temp;\r\n" +
" num--;\r\n" +
" }\r\n" +
"\r\n" +
" return b;\r\n" +
"} \r\n" +
"var out = java.lang.System.out;\n" +
"n = 1;" +
"while( n <= 100 ) {" +
" out.println(java.lang.Thread.currentThread().getName() +':'+ 'FIB('+ n +') = ' + fibonacci(n));" +
" n++;" +
" if (java.lang.Thread.interrupted()) {" +
" out.println('JS: Interrupted::'+Date.now());" +
" break;" +
" }" +
"}\n";
static {
manager = new ScriptEngineManager();
engine = manager.getEngineByName("JavaScript");
}
public static void main(final String... args) throws Exception {
for(int i = 0;i<5;i++) {
try {
final Bindings b = engine.createBindings();
final SimpleScriptContext sc = new SimpleScriptContext();
sc.setBindings(b, ScriptContext.ENGINE_SCOPE);
execWithFuture(engine, script,sc);
}
catch(Exception e) {
e.printStackTrace();
}
}
}
private static void execWithFuture(final ScriptEngine engine, final String script,final ScriptContext sc) throws Exception {
System.out.println("Java: Submitting script eval to thread pool...");
ExecutorService single = Executors.newSingleThreadExecutor();
Callable<String> c = new Callable<String>() {
public String call() throws Exception {
String result = null;
try {
engine.eval(script,sc);
} catch (ScriptException e) {
result = e.getMessage();
}
return result;
}
};
single.submit(c);
single.shutdown();
System.out.println("Java: ...submitted.");
}
}