caching problem?

[to...@virusbtn.com]

In trying to develop a simple perl script, I have run into some kind of 
caching problem which is making development an absolute nightmare.

The problem arises when I am using a subroutine. Whilst developing the 
subroutine, I (obviously) make errors in the code! I try the script out in 
the browser and get an error message, as you would expect. So then I 
revert the code back to what it was when it was working... try it in the 
browser again just to check, and I get an error message once again... 
strange, I just reverted the code back to what it was when I knew it was 
working.!

Sometimes, if I click refresh several times, it may suddenly decide to 
start working again. I can force it to work properly again by renaming the 
subroutine! Another way I can force it to start working again is to 
restart apache!

When the code is in such a state that I know for a fact it should be 
working, and the browser gives me an error... I can run the script 
successfully from the command line!!!

anyone ever had this (or a similar) problem????!!

-- 
Tom David Kirkpatrick
Virus Bulletin Web Developer, Virus Bulletin

Tel: +44 1235 555139
Web: www.virusbtn.com

Re: caching problem?

[Perrin Harkins <pe...@elem.com>]

On Tue, 2005-04-26 at 17:40 +0100, tom.kirkpatrick@virusbtn.com wrote:
> Sometimes, if I click refresh several times, it may suddenly decide to 
> start working again. I can force it to work properly again by renaming the 
> subroutine! Another way I can force it to start working again is to 
> restart apache!

Modules don't get reloaded automatically unless you use something like
Apache::Reload.  Apache::Registry scripts do get reloaded.  You haven't
told us anything about how you are developing (Registry?  Perl handlers?
Mason?) or even which version of mod_perl you have, so it's hard to give
you specific advice.  There is a lot of documentation on transitioning
from CGI programming to mod_perl in the on-line docs:
http://perl.apache.org/

- Perrin

Re: caching problem?

[Tom Schindl <to...@gmx.at>]

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tom.kirkpatrick@virusbtn.com schrieb:
| In trying to develop a simple perl script, I have run into some kind of
| caching problem which is making development an absolute nightmare.
|
| The problem arises when I am using a subroutine. Whilst developing the
| subroutine, I (obviously) make errors in the code! I try the script
out in
| the browser and get an error message, as you would expect. So then I
| revert the code back to what it was when it was working... try it in the
| browser again just to check, and I get an error message once again...
| strange, I just reverted the code back to what it was when I knew it was
| working.!
|
| Sometimes, if I click refresh several times, it may suddenly decide to
| start working again. I can force it to work properly again by renaming
the
| subroutine! Another way I can force it to start working again is to
| restart apache!
|
| When the code is in such a state that I know for a fact it should be
| working, and the browser gives me an error... I can run the script
| successfully from the command line!!!
|
| anyone ever had this (or a similar) problem????!!
|

That's not a problem its more a feature of mod-perl. Don't forget the
code you write gets compiled only once per-apache-process/thread.

The following happens:

apache_ctl restart
1. request
	=> handled by apache-child 1
	=> (no code loaded) compile code (code_1)
	=> execute code
	=> produces an error
revoke changes
2. request
	=> handled by apache-child 1
	=> execute code
	=> produces an error

3. request
	=> handled by apache-child 2
	=> (no code loaded) compile code (code_1)
	=> execute code
	=> successful

In short child1 and child2 have different versions of code and won't
recompile until you say them to do so.

2 ways out:
- -----------
- - always restart apache when files changed
- - use Apache::Reload/Apache2::Reload

Tom
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