On Tue, Aug 28, 2012 at 7:39 AM, Matijn Woudt <tijnema@xxxxxxxxx> wrote:
> On Tue, Aug 28, 2012 at 3:49 AM, Adam Richardson <simpleshot@xxxxxxxxx> wrote:
>> On Mon, Aug 27, 2012 at 6:54 PM, Matijn Woudt <tijnema@xxxxxxxxx> wrote:
>>> On Mon, Aug 27, 2012 at 10:56 PM, Haluk Karamete
>>> <halukkaramete@xxxxxxxxx> wrote:
>
> First of all, I believe PHP is smart enough to not generate bytecode
> for functions that are not used in the current file. Think about the
> fact that you can write a function with errors, which will run fine
> until you call the function. (except for syntax errors).
I believe this is untrue. PHP generates the bytecode and then parses
the bytecode per request to generate the userland infrastructure,
including classes and functions, for the entire include file. During
the generation of bytecode, PHP doesn't know apriori which functions
will be called at runtime. I suspect if you asked for confirmation of
this on the internals list, they'd confirm this. In terms of errors,
there are certainly different stages that errors can occur, and what
you're referring to are runtime errors. Runtime errors don't
necessarily show up in every possible execution branch. That doesn't
mean that PHP didn't generate the code for the userland functionality.
> The speed difference between loading 5K file or 50K file (assuming
> continuous blocks) is extremely small. If you split this library, you
> would have PHP files that require you to load maybe 3 or 4 different
> files to have all their functions.
Here's where I believe we have a communication issue. I never spoke of
splitting up the library into 3 or 4, or any number of different
files. The opening post states that only 10% of the pages need the
library. I suggested that he only include the library in the 10% of
the pages that need the library. That said, it's possible I
misinterpreted him.
I will say that I do disagree with your analysis that difference
between loading a 5K or 50K php file is extremely small. So I just put
this to the test.
I created a 5K file and a 50K file, both of which have the form:
function hello1(){
echo "hello again";
}
function hello2(){
echo "hello again";
}
etc.
I have XDegub installed, have APC running, warmed the caches, and then
test a few times. There results all hover around the following:
Including the 5K requires around 50 microseconds. Including the 50K
requires around 180 microseconds. The point is that there is a
significant difference due to the work PHP has to do behind the
scenes, even when functions (or classes, etc. are unused.) And,
relevant to the dialog for this current thread, avoiding including an
unused 50K PHP on 90% of the pages (the pages that don't need the
library) will lead to a real difference.
Adam
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