Peter Pilsl wrote:
> I just cant get the following in my brain. I have a modules that is
> started with apache using the PerlModule-directive in httpd.conf.
>
> This module defines a global pointer on startup that should be the
> same in all sub-instances of httpd and really in the current
> apache-session all instances print out : $g_ptr : HASH(0x8458a30)
>
> This hashpointer is later filled with different values (dbhandles,
> filehandles ...) that should kept open over more calls.
>
> Now each session has the same pointer, but the content of the
> anonymous hash its pointing too is different in each instance !!
>
> thread 1:
> $g_ptr : HASH(0x8458a30)
> $g_ptr->{counter} : SCALAR(0x85aa62c)
>
> thread 2:
> $g_ptr : HASH(0x8458a30)
> $g_ptr->{counter} : SCALAR(0x85f5e2c)
>
> A even more strange example is an anonmous array that has the same
> adress, but different content too.
>
> The only explanation is that there is some mem-mapping for each
> httpd-instance, but I dont know much about this.
>
> My problem now is, that each httpd-instance opens a lot of db-handles
> and connections and I end up with system-errors 'to many files opened'
> or such things.
>
> Is there any way to share handles between all instances (I guess not,
> and I'm sure this mem-mapping has a deeper meaning too: if more than
> one instance access the same adress at the same time there would be
> lot of troubles and I'm even more sure that this has something to do
> with the copy-on-write feature of fork(), but I'm just not good in
> this things, so I'd like to have some comment to be sure that this is
> a principal problem and not a problem of my module)
Peter, in the future posts please consider the following:
1. in perl we don't have pointers, but references. I think you'll be more
understood if you talk using the Perl terminology, rather than C.
2. it helps to diagnose a problem when a *short* (a few lines) code
example is shown, rather than just describing the symptoms.
This should give you directions to understanding your problem and
solving it:
1. forked children share the same datastructure with a parent until they
get modified. When this happens a copy on write occurs and the child
process doesn't share the datastructure anymore. See:
http://perl.apache.org/guide/performance.html#Know_Your_Operating_System
2. apparently you have the same problem as 'too many connections'
problem, and therefore want to look at Apache::DBI for understanding the
problem and coming up with a similar solution for your problem.
_____________________________________________________________________
Stas Bekman JAm_pH -- Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide http://perl.apache.org/guide
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