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Cc: George Schlossnagle <george@omniti.com>,
	Rasmus Lerdorf <rasmus@lerdorf.com>,
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Date: Tue, 9 Aug 2005 15:18:09 -0400
To: steve roussey <iamstever@gmail.com>
Subject: Re: [PHP-DEV] Moving to PHP5.1 and Apache 2.2 next year, need help
From: george@omniti.com (George Schlossnagle)


On Aug 9, 2005, at 3:12 PM, steve roussey wrote:

> On 8/8/05, Rasmus Lerdorf <rasmus@lerdorf.com> wrote:
>
>>> 3. Problems with thread-safety of modules
>>>
>>
>> You missed the most serious one.  Thread safety problems in random
>> libraries you link in and we have absolutely no control over those.
>>
>
> OK, I am confused. I always thought (an assumption with nothing to
> back it up, now that I think about it) that the core part of PHP was
> thread safe and that it was the third party libraries included from
> _extensions_ that were at issue.
>
> So if I used mysqli then it was at the mercy of the mysql library. So
> if the mysqli maintainer knew that that library was safe and their
> extension was safe then they could mark it as safe. All others would
> go through a single mutex, etc...
>
> But if PHP core uses a library and has no idea if it is safe or not
> (like glibc, though would run under such a system?) then I get your
> point. I hadn't considered it before. I suppose that is why MySQL
> statically links in such things that it knows works, not leaving
> anything to chance.

This can affect you even if you're not statically linked.   
Dynamically loaded libraries run in your address space and have the  
same ability to mess you up as statically linked libraries.   
Otherwise your understanding is spot-on.

Here there be dragons.

George