[webkit-dev] WTF::callOnMainThread() and re-entrancy

[Alexey Proskuryakov]

On 09.03.2010, at 11:23, Michael Nordman wrote:

> 1) We feel the need to change how Document::postTask() behaves,  
> because otherwise, the patch for <https://bugs.webkit.org/show_bug.cgi?id=34726 
> > doesn't work. We feel the need because it makes little sense for  
> it to have drastically different behavior depending on what thread  
> it's called from.
>
> It feels like a good change to make indeed, but I'm surprised that  
> it apparently went through review unmentioned and unquestioned. The  
> questions to ask are why exactly it was needed, and whether there  
> are other ways to fix bug 34726.
>
> This was discussed somewhat off list between dumi, dimich, and  
> myself (and whomever else dumi traded notes with). We were very  
> surprised that tasks scheduled via postTask() were not executed in  
> the same order as being scheduled.

Another way to fix just this aspect would be to piggy-back on existing  
task queue if it's non-empty, similar to what callOnMainThread() does.  
I'm not suggesting this, of course, as it still leaves us with a huge  
risk of race conditions and unexpected behaviors.

- WBR, Alexey Proskuryakov

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