Thread safety in WO (was Re: Picking up .wo changes)
Thread safety in WO (was Re: Picking up .wo changes)
- Subject: Thread safety in WO (was Re: Picking up .wo changes)
- From: Jonathan Rochkind <email@hidden>
- Date: Mon, 09 Jun 2003 11:42:32 -0500
At 08:07 AM 6/6/2003 -0700, Pierre Frisch wrote:
Concurrent request handling is the default behavior in WO 5.x and I would
not bank to much on the ability to disable it. I remember reading
somewhere that WO 5.x is always multithreaded and that you should never
make the single thread assumption.
Hm. It's true that WO 5.x is always multithreaded, in that more than
multiple threads will always exist at once. I do NOT think it's true that
WO 5.x handles requests concurrently by default. The documentation for
WOApplication.allowsConcurrentRequestHandling says "returns false by default."
The trick then, when you know that requests will not be handled
concurrently but that the app is multithreaded, is figuring out in what
circumstances more than one thread may be accessing any given piece of
code. And I'm not always sure. Various knowledgeable developers who I
respect have disagreed on this sort of thing on the list in the past.
For a piece of code that actually spans sessions, like an application-wide
cache of WOElement definitions, I would agree that to be on the safe side
you better write it in a thread-safe way, assuming the worst case in terms
of multiple threads wanting to access it at once.
--Jonathan
Something like this should do, should it not: (well, I have to load the
strings from somewhere too)
WOElement cachedTemplate;
public WOElement template()
{
if (cachedTemplate == null)
{
synchronized(cachedTemplate)
{
if (cachedTemplate == null)
cachedTemplate =
templateWithHTMLString(htmlString, wodString, languages);
}
}
return cachedTemplate;
}
This would address one level of cache. You probably would like to cache
the hit to the backing store when instantiating new components. You want
to implement that with Dictionaries based on component name and language.
I usually do a double level dictionary the first level is based on the
component name and the second on the language. When a search is
unsuccessful you probably want to tag it so as not to redo it.
Or perhaps I'll just forget about it all, and go back to PHP and MySQL
again...
At least there I can look at the source code, if I wonder about something.
If you don't care about performance, you don't need caching and all is
simple....
--anders
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.