Subj : Re: Access violation in JavaScript-C 1.5 pre-release 5 2003-01-10
To   : Rob Swindell <jseng@synchro.net>
From : Brendan Eich <brendan@meer.net>
Date : Tue May 06 2003 04:12 pm


>If the JS engine doesn't use any global or static variables, and a separate
>runtime is used per thread, why would there be any "thread safety" issues?
>Sorry for questioning your answer, but I just don't understand what
>necessitates the requirement. :-)
>  
>

The deflated string cache.  Because of very old (older than 
JS_THREADSAFE) API commitments in the form of JS_GetStringBytes and its 
many clients, that cache is global.  Notice the lack of a cx or rt 
parameter to JS_GetStringBytes.

>If a separate runtime is used per thread, no JS_BeginRequest/EndRequest
>calls are required though, correct?
>  
>

Correct.  But you can't share objects among runtimes, and you waste more 
memory on average than if you could share.

So since you'll need JS_THREADSAFE anyway, why not use fewer (say, one) 
runtimes?

/be

.