Nashorn MultiThread Programming

Question

Can you help me out if the following code will work in a multi-threaded application.

Here is my Java Script that will be evaluated by Nashorn

var Thread = Java.type("java.lang.Thread");
var referenceNumberValid = "0000";
var referenceNumberInvalid = "0001";

function validate (parameters) {
    var isValid = false;
    var statusCode;
    var referenceNumber = parameters.referenceNumber;
    var validateNumber = referenceNumber.substr(0, 7);
    var sum = 0;

    for (ctr = 0; ctr < validateNumber.length; ctr++) {
        sum += parseInt(validateNumber.substr(ctr, 1));
    }

    var checkDigit = sum % 10;
    isValid = parseInt(referenceNumber.substr(7, 1)) == checkDigit;
    statusCode = isValid ? referenceNumberValid : referenceNumberInvalid;

    print("Thread: " + Thread.currentThread().getId() + ", isValid: " + isValid + ", referenceNumber: " + referenceNumber + ", validateNumber: " + validateNumber + ", sum: " + sum + ", checkDigit: " + checkDigit + ", statusCode" + statusCode);

    return statusCode;
}

This is how I create my script engine

ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
engine.eval(myScript);

While Testing using Testng this works without any errors

@Test(dataProvider = "validReferenceNumbers", timeOut = 3000)
public final void testValidReferenceNumber(String referenceNumber) throws NoSuchMethodException, ScriptException {
    Map<String, String> parameters = new HashMap<>();
    parameters.put("referenceNumber", referenceNumber);   
    Invocable invocable = (Invocable) engine;
    Object result = invocable.invokeFunction("validate", parameters);       
    Assert.assertEquals(statusCode, "000");
}

@DataProvider(name = "validReferenceNumbers")
private Iterator<Object[]> validReferenceNumbers() throws FileNotFoundException {
    Iterator<Object[]> testData = null;  
    // please assume that will be initilized correctly 
    return testData;
}

Test Results1 - note that some data are repeated

Thread: 10, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 11, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 12, isValid: true, referenceNumber: 17028884, validateNumber: 1702888, sum: 34, checkDigit: 4, statusCode0000
Thread: 13, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 14, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 15, isValid: true, referenceNumber: 17098881, validateNumber: 1709888, sum: 41, checkDigit: 1, statusCode0000
Thread: 16, isValid: true, referenceNumber: 17098881, validateNumber: 1709888, sum: 41, checkDigit: 1, statusCode0000
Thread: 17, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 18, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 19, isValid: true, referenceNumber: 17058887, validateNumber: 1705888, sum: 37, checkDigit: 7, statusCode0000
Thread: 20, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 21, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 22, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 23, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 24, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 25, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 26, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 27, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 28, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 29, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 30, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 31, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 32, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 33, isValid: true, referenceNumber: 17058887, validateNumber: 1705888, sum: 37, checkDigit: 7, statusCode0000
Thread: 34, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 35, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 36, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 37, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 38, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 39, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 40, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 41, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 42, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 43, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 44, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 45, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 46, isValid: true, referenceNumber: 07034880, validateNumber: 0703488, sum: 30, checkDigit: 0, statusCode0000
Thread: 47, isValid: true, referenceNumber: 07034880, validateNumber: 0703488, sum: 30, checkDigit: 0, statusCode0000
Thread: 48, isValid: true, referenceNumber: 07009882, validateNumber: 0700988, sum: 32, checkDigit: 2, statusCode0000

But if I add "parallel=true" to the @DataProvider my scripts starts to fail

@Test(dataProvider = "validReferenceNumbers", timeOut = 3000)
public final void testValidReferenceNumber(String referenceNumber) throws NoSuchMethodException, ScriptException {
    Map<String, String> parameters = new HashMap<>();
    parameters.put("referenceNumber", referenceNumber);   
    Invocable invocable = (Invocable) engine;
    Object result = invocable.invokeFunction("validate", parameters);       
    Assert.assertEquals(statusCode, "000");
}

@DataProvider(name = "validReferenceNumbers", parallel=true)
private Iterator<Object[]> validReferenceNumbers() throws FileNotFoundException {
    Iterator<Object[]> testData = null;  
    // please assume that will be initilized correctly 
    return testData;
}

Test Results2 - note that some data are repeated to show that the same reference number could fail randomly during the test

Thread: 29, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 22, isValid: false, referenceNumber: 18058888, validateNumber: 1805888, sum: 1, checkDigit: 1, statusCode0001
Thread: 25, isValid: false, referenceNumber: 18058888, validateNumber: 1805888, sum: 1, checkDigit: 1, statusCode0001
Thread: 21, isValid: true, referenceNumber: 17098881, validateNumber: 1709888, sum: 41, checkDigit: 1, statusCode0000
Thread: 27, isValid: false, referenceNumber: 18028885, validateNumber: 1802888, sum: 1, checkDigit: 1, statusCode0001
Thread: 20, isValid: true, referenceNumber: 17098881, validateNumber: 1709888, sum: 41, checkDigit: 1, statusCode0000
Thread: 26, isValid: true, referenceNumber: 17058887, validateNumber: 1705888, sum: 37, checkDigit: 7, statusCode0000
Thread: 24, isValid: true, referenceNumber: 17028884, validateNumber: 1702888, sum: 34, checkDigit: 4, statusCode0000
Thread: 23, isValid: false, referenceNumber: 18028885, validateNumber: 1802888, sum: 1, checkDigit: 1, statusCode0001
Thread: 28, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 30, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 32, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 34, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 31, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 36, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 38, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 40, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 42, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 44, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 33, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 46, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 48, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 35, isValid: false, referenceNumber: 18058888, validateNumber: 1805888, sum: 30, checkDigit: 0, statusCode0001
Thread: 50, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 37, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 39, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 41, isValid: true, referenceNumber: 17058887, validateNumber: 1705888, sum: 37, checkDigit: 7, statusCode0000
Thread: 52, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 54, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 43, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 45, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 56, isValid: true, referenceNumber: 07009882, validateNumber: 0700988, sum: 32, checkDigit: 2, statusCode0000
Thread: 58, isValid: true, referenceNumber: 07034880, validateNumber: 0703488, sum: 30, checkDigit: 0, statusCode0000
Thread: 47, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 49, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 51, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 53, isValid: true, referenceNumber: 18028885, validateNumber: 1802888, sum: 35, checkDigit: 5, statusCode0000
Thread: 55, isValid: true, referenceNumber: 18058888, validateNumber: 1805888, sum: 38, checkDigit: 8, statusCode0000
Thread: 57, isValid: true, referenceNumber: 07034880, validateNumber: 0703488, sum: 30, checkDigit: 0, statusCode0000

Can anyone confirm if I can Initialize the ScriptEngine and allow it to be used in a multithreaded application. As you can see I use global script variables but those will not be modified during its execution. As our design revolves around a web service that calls this script internally.

P.S. In my understanding @DataProvider(parallel=true) is the proper way to test the multithreading, so If I am wrong please point it out.

Edit Can anyone tell me how I can modify my code/script so that I can initialize the ScriptEngine and allow it to be used in a multi-threaded application. As I do not want to parse the script files over and over again.

As I previously thought that if the script does not use global variables to keep state it would be OK, but apparently that is not enough.

Thanks

Nashorn is [not thread-safe](https://blogs.oracle.com/nashorn/entry/nashorn_multi_threading_and_mt). Is that what you are asking? — Sean Bright, Mar 15 '16 at 14:43
Hi, thanks for the comment. Actually what I am asking is what is the proper approach so that I can compile my script in and use it a multi-threaded application if it is even possible. As I previously thought that if I put all my data manipulation inside the function and not use global variables to keep state that would be enough. — Jefrey Valencia, Mar 15 '16 at 16:11

score 7 · Accepted Answer · edited May 23 '17 at 11:53

7

You can initialize a ScriptEngine and use it in a multithreaded application.

Instead of engine.eval(myScript); you'll want to create a CompiledScript instance that you can later evaluate into Bindings instances:

Compilable compilable = (Compilable) engine;
CompiledScript script = compilable.compile(myScript);

And instead of using your engine as an Invocable you'll need to create a Bindings instance for each thread/test, evaluate the compiled script into it, get the script object mirror that wraps the function, and then call the function:

@Test(dataProvider = "validReferenceNumbers", timeOut = 3000)
public final void testValidReferenceNumber(String referenceNumber) throws ScriptException {
    Map<String, String> parameters = new HashMap<>();
    parameters.put("referenceNumber", referenceNumber);
    Bindings bindings = engine.createBindings();
    script.eval(bindings);
    ScriptObjectMirror scriptObjectMirror = (ScriptObjectMirror) bindings.get("validate");
    Object result = scriptObjectMirror.call(null, parameters);
    /* insert result assertions here */
}

Sources:

edited May 23 '17 at 11:53

Community

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answered Mar 15 '16 at 19:57

mfulton26

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Hi Thanks for the answer this works for me. However, just one follow up question. What does the "this" parameter do in "scriptObjectMirror.call(this, parameters)" – Jefrey Valencia Mar 16 '16 at 04:24
@JefreyValencia, good question. After further investigation it looks like it becomes the `thiz` in `func.apply(thiz, args)` in JavaScript (see [Function.prototype.apply() - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply)). I've updated the code sample to use `null` instead. Thanks! – mfulton26 Mar 16 '16 at 13:36
@ mfulton26, Thanks again – Jefrey Valencia Mar 16 '16 at 23:15
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On a different note, calling CompiledScript.eval(Binding b) will apply changes to the bindings that are part of its contained ScriptEngine and not the ones that you pass as argument. Big difference there. – NishM Aug 20 '16 at 04:27
I tried doing exactly this and storing the ScriptObjectMIrror objects in a ThreadLocal object and it does not appear to be thread safe. This might be related to what @NishM mentioned above. Did anyone actually get this running in multiple threads? – Mr. Adobo Dec 06 '16 at 09:37
It's been awhile since I looked at this but I found the code I used to experiment, etc. I've created a gist for it at https://gist.github.com/mfulton26/8c18f8cc1055f7137c4caf6ab751e89e. From what I can tell, running the tests in parallel behaves correctly. – mfulton26 Dec 06 '16 at 13:42
@JesusAdoboLuzon My current setup is serving multiple threads. There is a ThreadLocal ScriptEngine with a ThreadLocal CompiledScripts cache. Bindings are copied and cached. Though i am not quite happy with the amount of objects created by this setup , jmeter tests are passing successfully for a million requests. ( 100 simultaneous threads). – NishM Dec 06 '16 at 19:09

Nashorn MultiThread Programming

1 Answers1