Subj : Re: Performance Advice on Maintaining Many Contexts
To   : Peter Kyme
From : Brendan Eich
Date : Wed Mar 02 2005 05:22 pm

Peter Kyme wrote:
> My problem involves a system containing a large number (> 100) of
> objects, each of which has an associated Spidermonkey context.
> 
> The objects execute a small javascript repeatedly, iterating until
> termination. This javascript is user defined, and so may contain
> arbitrary local variables,


Do you really mean local as in function-local, or just top-level vars 
private to the script?  If the latter, you need a global object per 
script to hold those global vars, but not a context per script unless 
you are executing scripts concurrently.


> which was my motivation for creating a
> context per object (no multithreading is involved).


A JSContext is the state you need to execute concurrently, so if you 
have only one thread, you need no more than one JSContext.

Why did you make a context per object?


> This appears to work well, but I've encountered a nasty performance
> issue at cleanup time. Running the program through once, without doing
> any memory cleanup takes ~1.2s. If I then add code to destroy the JS
> contexts before exits, the program take ~17s to execute.


What version of the engine are you using?

/be

.