New Post: Performance...

August 6, 2014, 6:36 am

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Thanks for posting that, UweKeim! Just to clarify, ClearScript's JScriptEngine class defaults to the JScript 5.7 feature set. Specifying WindowsScriptEngineFlags.EnableStandardsMode selects the JScript 5.8 feature set, which includes the JSON object.

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New Post: Parameter number conflict.

August 6, 2014, 6:40 am

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Perhaps something like this:

engine.AddHostObject("$", new DollarSignFunc((arg1, arg2) => {
    var name = arg1 asstring;
    if (name == null)
        new Window(f).AddEventHandler("Load", arg1);
    elseif (arg2 != null)
        new Window(f).AddEventHandler(name, arg2);
    else {
        // add code here
    }
}));

As long as the calling pattern can be inferred from the arguments, you can support as many as you need.

Cheers!

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New Post: Performance...

August 6, 2014, 7:03 am

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UweKeim/ClearScript -

Thank you for the detailed information. This will really help!

Jules

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New Post: Parameter number conflict.

August 6, 2014, 7:09 am

≫ Next: New Post: get js of function

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thanks it works

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New Post: get js of function

August 6, 2014, 10:19 am

≫ Next: New Post: implement uneval function

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is it possible to get the source of an js function via js?

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New Post: implement uneval function

August 6, 2014, 10:36 am

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how is it possible to implement an uneval function?

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New Post: get js of function

August 6, 2014, 12:43 pm

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Sure, take a look at Function.prototype.toString().

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New Post: implement uneval function

August 6, 2014, 12:46 pm

≫ Next: New Post: implement uneval function

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Perhaps you could start with JSON.stringify() and incorporate Function.prototype.toString()?

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New Post: implement uneval function

August 6, 2014, 1:58 pm

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i would like to implement it in c# as a function for js

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New Post: implement uneval function

August 7, 2014, 9:22 am

≫ Next: New Post: ecmascript 6

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Hi furesoft,

You can use DynamicObject.GetDynamicMemberNames() to enumerate the properties of a script object.

However, you'll have to invoke script functions to retrieve various information such as function source code, whether an object is a function, whether one object is the same as another (for cycle detection), etc. A full uneval() implementation without the script engine's help may not be possible.

Consider also that script invocations are expensive, whereas uneval() can be implemented fully in JavaScript without any hops across the host-script boundary.

Good luck!

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New Post: ecmascript 6

August 7, 2014, 11:41 am

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when is it possible to use ecmascript 6 implementation?

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New Post: ecmascript 6

August 7, 2014, 12:36 pm

≫ Next: New Post: Serializing a compiled script

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Hi furesoft,

We have no plan to explicitly enable Harmony support while it's in development. Presumably the V8 team will enable Harmony features by default sometime after the standard is finalized and V8's implementation of the standard is complete.

Thanks for your question!

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New Post: Serializing a compiled script

August 7, 2014, 8:27 pm

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Is it possible to serialize a compiled script? For instance do something like:

byte[] result = null;
using (var clearscriptV8 = new V8Runtime())
using (var stream = new MemoryStream())
{
    var compiled = clearscriptV8.Compile(jsCode);
    var formatter = new BinaryFormatter();
    formatter.Serialize(stream, compiled);
    stream.Flush();
    stream.Position = 0;
    result = stream.ToArray();
}

and then at some point later on deserialize it and call a function within the script?

V8Script compiledScript;

using (var stream = new MemoryStream(serializedScript))
{
    var formatter = new BinaryFormatter();
    stream.Seek(0, SeekOrigin.Begin);
    compiledScript = formatter.Deserialize(stream) as V8Script;
}

using (var engine = new V8ScriptEngine(V8ScriptEngineFlags.DisableGlobalMembers))
{
    engine.Evaluate(compiledScript);
    return engine.Script.MyMethod(new { Something=true }) as IEnumerable<Result>;
}

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New Post: Serializing a compiled script

August 8, 2014, 7:10 am

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Hello!

Unfortunately V8Script instances are not serializable. More information here.

Thanks!

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New Post: Serializing a compiled script

August 8, 2014, 7:20 am

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Is this something that can be changed in ClearScript or is it a limitation of V8?

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New Post: Serializing a compiled script

August 8, 2014, 7:44 am

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its a limitation of .net

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New Post: Serializing a compiled script

August 8, 2014, 8:35 am

≫ Next: New Post: Increasing memory during V8 usage

≪ Previous: New Post: Serializing a compiled script

Hi again,

V8 doesn't support serialization of compiled scripts, but it does have a somewhat similar feature that ClearScript currently doesn't leverage.

In V8, script compilation optionally produces a binary artifact that supports offline storage and can be used to speed up the recompilation of the same script. This data could be combined with the original script code to produce a single object that supports standard .NET serialization and can reconstitute the compiled script faster than normal compilation.

Support for this feature is on our long-term to-do list.

Cheers!

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New Post: Increasing memory during V8 usage

August 8, 2014, 8:45 am

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Hi,

i have a memory problem and i don't know if it is due to a wrong usage or a problem in the engine.
When I use the V8 engine a long time with many JS-calls from C#:

using (var compiledFunction = m_Engine.Compile(function))
{
    var result = m_Engine.Evaluate(compiledFunction);
    Log.Debug("Result of function '" + function + "': " + result);
}

(also tried: engine.Execute(function);)

and many calls from JS to C# through an object I attached to engine.Script

engine.Script["nameOfObject"] = theObject;

(also tried: engine.AddHostObject("nameOfObject", theObject);)

the memory usage is increasing constantly.
I used DebugDiag2 to see what could cause that problem. Most of the memory is allocated by v8_x64.dll

Module Name   v8_x64 
Allocation Count   466 allocation(s) 
Allocation Size   1.02 GBytes 

---

Function details

Function   v8_x64!v8::Testing::DeoptimizeAll+109ccd 
Source Line    
Allocation type   Virtual memory allocation(s) 
Allocation Count   460 allocation(s) 
Allocation Size   530.3 MBytes 
Leak Probability   84%

and here is a call stack sample

Call stack sample 3

Address   0x00000000`22000000 
Allocation Time   14:43:09 since tracking started 
Allocation Size   8.02 MBytes 

LeakTrack+229ef    
v8_x64!v8::Testing::DeoptimizeAll+109ccd    
v8_x64!v8::Testing::DeoptimizeAll+c6037    
v8_x64!v8::Testing::DeoptimizeAll+c65b7    
v8_x64!v8::Testing::DeoptimizeAll+c9eb8    
v8_x64!v8::Testing::DeoptimizeAll+248ff    
v8_x64!v8::Testing::DeoptimizeAll+88b5c    
v8_x64!v8::Testing::DeoptimizeAll+52fd8    
v8_x64!v8::Testing::DeoptimizeAll+53324    
v8_x64!v8::Testing::DeoptimizeAll+4ef50    
v8_x64!v8::Testing::DeoptimizeAll+1337c4    
v8_x64!v8::Testing::DeoptimizeAll+133a30    
v8_x64!v8::Testing::DeoptimizeAll+111885    
v8_x64!v8::Script::New+236    
v8_x64!v8::Script::New+31    
ClearScriptV8_64+5a8e    
0x7FE916BF3C1

Do you see something what I am doing wrong or do you have some hints what else I can try?

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New Post: Increasing memory during V8 usage

August 8, 2014, 1:06 pm

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Hello querdenker,

It doesn't look like you're doing anything wrong. Can you say any more about the sort of work your scripts are doing?

Some general suggestions:

Make sure you're using the latest version of ClearScript. A number of memory leaks have been fixed since the last point release.
Is it possible that your scripts are generating increasing amounts of data that is reachable from the global/root object?
Try to avoid script compilation as much as possible. Consider using compiled scripts or direct invocation of script functions to re-execute script code.
We've found that when it comes to garbage collection, V8 is lazy to an extent that can get it in trouble. Consider invoking the garbage collector explicitly via ScriptEngine.CollectGarbage(true). Use a schedule that makes sense for your application - periodically or based on idle state, maximum invocation count, etc.
If all else fails, consider disposing the script engine and spinning up a fresh instance once in a while - again, using a schedule that makes sense for you.

Good luck!

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New Post: Parallel / web workers

August 8, 2014, 1:59 pm

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Is there any support for parallelism or web workers in clearscript? I would like to do parallel processing within my javascript code instead of having .net facilitate it because of the overhead of creating the engine in each thread.

Do you have a roadmap you can share? If this isn't on it will you consider adding it?

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