Re: Sharing readonly data between processes

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Thanks Perrin your answers are as I suspected.

Tom

Perrin Harkins wrote:
> Tom Schindl wrote:
> 
>> Loading/Parsing the XML before Apache forks its children and not 
>> modifying the data from this point on all apache/mp children will 
>> share the same data and it would not be copyied to each of them, 
>> copying only takes place when the data is modified. Is this true or 
>> have I got something wrong.
> 
> 
> It's mostly true, but an XML object is usually something complex which 
> may alter data in some way when you call methods to read it.  Even 
> reading a variable as a string when it had previously only been read as 
> a number causes a write in perl.  It doesn't unshare the entire thing 
> when that happens, but you do lose in 4K chunks (or whatever the page 
> size is on your OS).
> 
>> 2.
>> Is this also true when running e.g. under a thread mpm on mod_perl2, 
>> e.g. when you are on windows?
> 
> 
> No, there is no equivalent copy-on-write concept with threads on 
> Windows.  There you would have to declare it shared between threads, 
> which has catches with objects and may not be safe with this module. 
> Read the threads man pages for more.
> 
> - Perrin
> 
>