Re: Re: sysvsem extention question

From: Date: Fri, 24 Aug 2001 01:47:21 +0000
Subject: Re: Re: sysvsem extention question
Groups: php.dev php.general 
Request: Send a blank email to php-dev+get-64207@lists.php.net to get a copy of this message
> > Last, i don't see why the implementation as exists, requires 3 > > semaphores. I just looked over the code, and the reason for this is it specifically designed for a multi-process web environment. The most common method for semaphore initialization is in the parent process right before fork. There is no parent initializer for a php module author, and since each child has its own environment, there is no way to know when to initialize the semaphore. The way that Tom solved that problem was to create a "USAGE" semaphore which is used to insure that the semaphore is only initialized once. There must have been some sort of race condition because the purpose of the 3rd semaphore is a lock. This is actually a sharp way to handle the problem of no central way to initialize. -Jason

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