Posted by Erwin Moller on 12/06/06 16:59

CptDondo wrote:

> I am working on an embedded system. The entire configuration for the
> system is stored in an XML file, which is pretty long.
>
> It takes about 3 seconds to open the file using domxml_open_file.
>
> Breaking the file into smaller files is not possible; a single XML file
> is a part of the design requirement.
>
> Right now we're opening and freeing the file every time any data is
> requested from the file, which is quite often. This means that the user
> ends up waiting about 5 seconds total before the page is generated.
>
> It would be nice if we could open the file once per session, and keep
> the file open throughout the session, rereading only when the file on
> disk changes.
>
> Is this possible?

Hi Yan,

Yes, this is possible, but I seriously doubt it will increase performance.
Say you have a 1 MB file.
You store it into the session like $_SESSION["hugestructure"] = <yourfile>.

When the script end, the session is serialized and written to a sessionfile
in some sessiondirectory.

Next time that session is needed, the whole file must be read back into
memory in $_SESSION["hugestructure"], even if you don't use it.

I expect the overhead of serializing the file and safing it to disk takes
even longer than just opening it when needed.

Personally I would rethink the design of the application. Do you really need
such a huge file so often? Which information is used? Can you translate the
file to a few tables in a database and just query what you need when you
need it?

If this is no option for you, you might try a 'shared memory' approach in
PHP.
Here is more info:
http://nl3.php.net/manual/en/ref.shmop.php

I never did such a thing, so my advise ends here. :-)

Best of luck.
Regards,
Erwin Moller

>
> Thanks,
>
> --Yan

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