Malte Ubl wrote:
Hi,
I'd really appreciate some help with a really weird mod_perl problem we
keep running into.
This is mod_perl version 1.29 using Apache::PerlRun
The application servers of our mod_perl site occasionally (once every
2-3 weeks) start spitting out these error messages:
[Sun Jul 3 14:58:01 2005] [error] Modification of a read-only value
attempted at
/usr/local/lib/perl5/site_perl/5.8.6/i686-linux/Apache/PerlRun.pm line
215.\n
At first only a couple Apache childs seem to be affected but after a
while the error comes on every single request, so the whole website
comes to a stall.
Can you reproduce the problem at will?
The problem only accurs if the central mainframe we are working against
is having a problem and we are doing a lot of error handling. However,
the problem does not alway occur if there is a problem with the
mainframe and all processing that actually does get started finishes
totally fine.
The relevant line in PerlRun.pm is
sub readscript {
my $pr = shift;
$pr->{'code'} = $pr->{r}->slurp_filename; # this is line 215
}
My understanding of the "Modfication of read-only..." error is that it
cant really occur on that line, since there are no literals being modified.
Any help or pointer in the right direction would be really appreciated.
If the solution is to move away from Apache::PerlRun to something else
that would be alright, too. We'd like to avoid it though, because we are
satisfied with the speed and don't want to repeat the whole testing phase.
Quite often the error line is reported incorrectly. You can always add
something like:
#line 215
$pr->{'code'} = $pr->{r}->slurp_filename;
That's a special directive telling perl that the next line number is 215,
so you will know for sure that this is the line it's talking about.
Once you figure out the exact line, you need to figure out where the error
is coming from? You could use Devel::Peek to see what variable is
readonly. e.g.:
use Devel::Peek;
my $x = 5;
Dump $x;
For example $$ is readonly, so you get:
perl -MDevel::Peek -le 'Dump $$'
SV = IV(0x805d9b0) at 0x805b7cc
REFCNT = 1
FLAGS = (IOK,READONLY,pIOK)
IV = 16911
You can see the readonly flag set.
--
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