VBScriptEngine.AddHostType memory/handle leak

[winkxoe]

It looks like a memory/handle leak was added sometime between versions 5.5.4 and 5.5.5 when calling AddHostTiype from an instance of VBScriptEngine. I think it also affects the JScriptEngine, but not the V8ScriptEngine.

[ClearScriptLib]

HI @winkxoe,

Can you provide more information? How are you detecting the leak? Do you know what objects are leaked?

Thanks!

[winkxoe]

I have a application that spins off a new thread every few seconds and runs a simple VB script using VBScriptEngine. After it's done running the script it disposes the VBScriptEngine. It also uses AddHostType to add a class that enables the script to log to the same log file as the rest of the application. We were using version 5.4.6 for a long time without any problems. I upgraded to 5.5.6 and the application would grow to over 9 GB of memory over a 24 hour period and slow the entire server down. Then I tried 5.6.0 and had the same problem. Then I did an awful lot of testing to try to isolate the problem. I went back an tried versions 5.5.3, 5.5.4, and 5.5.5. Versions 5.5.3 and 5.5.4 work fine. Right now we're running 5.5.4 without the application growing. It was also clear from my testing that it would not grow if I removed the AddHostType call for the logging class. I tested the V8ScriptEngine in a similar situation with the same AddHostType call for the logging class. The application didn't appear to grow with V8. It's probably not the best practice to create and dispose of so many instances of the engine. In this case it seems to work for what we need it for. I hope this helps! Thank you for supporting ClearScript! It's a wonderful tool! From: ClearScript Library [mailto:notifications@github.com] Sent: Thursday, September 19, 2019 9:44 AM To: microsoft/ClearScript Cc: Wineke, Steve; Mention Subject: Re: [microsoft/ClearScript] VBScriptEngine.AddHostType memory/handle leak (#135) HI @winkxoe <https://github.com/winkxoe> , Can you provide more information? How are you detecting the leak? Do you know what objects are leaked? Thanks! - You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#135?email_source=notifi cations&email_token=ANHE72GCJLCUZIH622S7243QKN6YHA5CNFSM4IYA4A42YY3PNVWW K3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD7DQLUY#issuecomment -533136851> , or mute the thread <https://github.com/notifications/unsubscribe-auth/ANHE72H5EIQGYN626UIBM VTQKN6YHANCNFSM4IYA4A4Q> .

[ClearScriptLib]

Hi @winkxoe,

A couple of questions:

1. Which AddHostType overload are you using?
2. Can you reproduce the leak simply by adding the AddHostType call? Or does it only happen if you call methods on the exposed type from script code?

Thanks!

[winkxoe]

I'm using AddHostType(string itemName, SystemType type); I didn't have to call any methods on the exposed type. I actually reduced the script to simply setting a string as shown in the example below and I saw the leak. Dim nextfile nextfile = "The very next file" From: ClearScript Library [mailto:notifications@github.com] Sent: Friday, September 20, 2019 8:19 AM To: microsoft/ClearScript Cc: Wineke, Steve; Mention Subject: Re: [microsoft/ClearScript] VBScriptEngine.AddHostType memory/handle leak (#135) Hi @winkxoe <https://github.com/winkxoe> , A couple of questions: 1. Which AddHostType <https://microsoft.github.io/ClearScript/Reference/html/Overload_Microso ft_ClearScript_ScriptEngine_AddHostType.htm> overload are you using? 2. Can you reproduce the leak simply by adding the AddHostType call? Or does it only happen if you call methods on the exposed type from script code? Thanks! - You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#135?email_source=notifi cations&email_token=ANHE72HH5Q7LCC4K55I4VMTQKS5R5A5CNFSM4IYA4A42YY3PNVWW K3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD7GQG7Y#issuecomment -533529471> , or mute the thread <https://github.com/notifications/unsubscribe-auth/ANHE72FJ5BQKJOOIEXLKS ADQKS5R5ANCNFSM4IYA4A4Q> .

[ClearScriptLib]

Hi @winkxoe,

Unfortunately we haven't been able to reproduce your issue so far with ClearScript 5.6.0. In a test program we construct a VBScriptEngine instance, expose the Console type, and execute a small script. After 100,000 iterations the program's private memory size is around 12 MB.

Can you create a minimal sample program that reproduces the issue?

Thanks!

[winkxoe]

Can you try this chunk of code? I noticed that if I removed either the AddHostType or the engine.Script["nextfile"] the leak seemed to go away. However both of them together and it grows fast. while (!stop) { string text = "Dim nextfile\n" + "nextfile = \"The very next file\""; using (var engine = new VBScriptEngine()) { engine.AddHostType("Logger", typeof(Console)); engine.Script["nextfile"] = ""; engine.Execute(@text); } } From: ClearScript Library [mailto:notifications@github.com] Sent: Friday, September 20, 2019 1:01 PM To: microsoft/ClearScript Cc: Wineke, Steve; Mention Subject: Re: [microsoft/ClearScript] VBScriptEngine.AddHostType memory/handle leak (#135) Hi @winkxoe <https://github.com/winkxoe> , Unfortunately we haven't been able to reproduce your issue so far with ClearScript 5.6.0. In a test program we construct a VBScriptEngine instance, expose the Console type, and execute a small script. After 100,000 iterations the program's private memory size is around 12 MB. Can you create a minimal sample program that reproduces the issue? Thanks! - You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#135?email_source=notifi cations&email_token=ANHE72F4GBXSNOFFNSUR6ATQKT6UDA5CNFSM4IYA4A42YY3PNVWW K3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD7HJVHY#issuecomment -533633695> , or mute the thread <https://github.com/notifications/unsubscribe-auth/ANHE72G25JJGUOS3EBVFN O3QKT6UDANCNFSM4IYA4A4Q> .

[ClearScriptLib]

@winkxoe,

Thanks for posting the sample code! We've reproduced the issue and will investigate.

Cheers!

[ClearScriptLib]

Hi @winkxoe,

This looks like a bug in COM Interop. We'll have a workaround in the next ClearScript release. In the meantime, you might be able to bypass the issue by replacing this:

engine.Script["nextfile"] = "";

with this:

engine.Script.nextfile = "";

Good luck!

[winkxoe]

Great! Thank you very much!

[ClearScriptLib]

Fixed in ClearScript 6.0.