CODEWITHSUNDEEP
phpcachingapc
blacktie24
blacktie24

Reputation: 5075

Question of PHP cache vs compile

from my understanding, if you use a PHP caching program like APC, eAccelerator, etc. then opcodes will be stored in memory for faster execution upon subsequent requests. My question is, why wouldn't it ALWAYS be better/faster to compile your scripts, assuming you're using a compiler like phc or even HPHP (although I know they have issues with dynamic constructs)? Why bother storing opcodes since they have to be re-read by the Zend Engine, which uses C functions to execute it, when you can just compile and skip that step?

Upvotes: 5

Views: 601

Answers (2)

Marc B
Marc B

Reputation: 360662

If PHP didn't have eval(), it probably would be possible to do a straight PHP->compiled binary translation with (relative) ease. But since PHP can itself dynamically build/execute scripts on the fly via eval(), it's not possible to do a full-on binary. Any binary would necessarily have to contain the entirety of PHP because the compiler would have no idea what your dynamic code could do. You'd go from a small 1 or 2k script into a massive multi-megabyte binary.

Upvotes: 1

Byron Whitlock
Byron Whitlock

Reputation: 53861

You cannot simply compile to c and have your php script execute the same way. HPHP does real compilation, but it doesn't support the whole superset of php features.

Other compilers actually just embed a php interpreter in the binary so you aren't really compiling the code anyway.

PHP is not meant to be compiled. opcode caching is very fast and good enough for 99% of applications out there. If you have facebook level of traffic, and you have already optimized your back end db, compilation might be the only way to increase performance.

PHP is not a thin layer to the std c library.

Upvotes: 2

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