[webkit-dev] WebKit bug in Dashboard widget?

Timothy Hatcher timothy at hatcher.name
Sun Jul 10 18:09:23 PDT 2005

First I would like to point out this mailing list if for discussions  
about WebKit internal development. There is webkitsdk- 
dev at lists.apple.com for discussions about development of applications/ 
widgets using WebKit. You might have more exposure there.

Simply locking around WebKit's WebView wont solve this problem. The  
reason is you don't know what other Cocoa classes or System APIs  
WebKit uses that aren't thread safe. Most Cocoa classes are publicly  
listed as not thread safe.

There is a list of thread safe classes and other information here:


You might want to rethink your design, calling WebKit from only the  
main thread. This will save you many headaches. Most of WebKit's API  
is non-blocking and callback/delegate based, so threads really aren't  

— Timothy Hatcher » colloquy.info

On Jul 10, 2005, at 7:51 PM, Ben Kazez wrote:

> In fact, I am calling WebKit APIs from multiple threads, which  
> wasn't a good idea on my part. This is my first experience with  
> multiple threads, and I'm enjoying it but am still quite a novice.  
> My only WebKit call is to [WebView - 
> stringByEvaluatingJavaScriptFromString:], so I've changed it to
>     [_webViewLock lock];
>     [_webView  
> stringByEvaluatingJavaScriptFromString:endHandlerJavaScript];
>     [_webViewLock unlock];
> where _webViewLock is an instance variable in the Dashboard plugin  
> object. However, the crash still happens -- some elements too tall,  
> others too short, elements disappearing until you mouse over them,  
> and then EXC_BAD_ACCESS. Should my locking code above have worked?  
> (I can move this discussion to Cocoa-dev if it becomes off-topic  
> for this list.)
> Thank you very much for your help.

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