Kai Xiang wrote: > Hello all: > > I'm new here and looking PHP these days, howerver , I'm confused by how it > works, and here is some questions I have. > Is there any old bird wanna help me out? > > 1. I heard there is a zend engine inside PHP playing the role as a virtual > machine, and PHP excution have 2 step, first compile to opcode and then > excute the opcode, > so is that means the php are compiled only once per file? or still need to > recompile when another request issued to the server? also I heard about the > caching extention about php, is it talking about caching the opcode? is't > caching the opcode or excute results? how it shares between the requests?
there are opcode caching mechanisms available (e.g. php.net/apc - which needs to be installed via 'pecl'**); however the standard php installation will not do any opcode caching (i.e. compilation to opcode is done at each request). ** pecl.php.net / pear.php.net > > 2. Is there some alternative choise except zend engineen, why need a zend > engine? for performance advantage or just easy for porting to different > platform? no, there is no plugin replacement for the zend engine and AFAIK the zend engine is not used in any other products apart from php ... maybe zend.com has an article on what exactly the zend engine is (I have never really bothered to find out myself :-). > > 3. Take linux apache for example, if compiled as a apache module, and using > prefork threading model, for example, if I have 100 process, is that > means I > have 100 copy of PHP library local data(I assume only one reentrant > excutable image) in each process? compare to a worker model, like 10 > process > and 10 threads in each one process, should it make a difference that we > only > have 10 copy of PHP library local data ? php is not threadsafe (well actually some php extensions are not thread safe ... it's an unknown quantity) the prefork worker module for apache2 is the only recommended way to go (if running as an apache module) you might want to look into the FastCGI SAPI if you need a speed boost ... I can't tell you anything about it because I have no experience with it as such. > > I'm not sure if this is the right place to talk about this, anyway, if you > know a better place, help me out :) this is the place - always best to ask here first; if what your asking is better aimed at the developers list someone here will point you in the right direction. > Thanks in advantage > > Regards > Kai > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
