Trouble with script execution
I am having a nproblem executing my handler.
The short of it is it is when I make a change to the script I have to
restart the server to get it noticed, and it does not always call the
same code.
The lng of it:
I have a package with a 'handler' function.
It starts...
package Apache::Script;
use strict;
use Apache2::Const qw(:common);
use Apache2::Connection;
[snip]
sub handler {
warn Apache::Script::handler $$ '.join(, , @_).';
my $r = shift;
[snip]
Many more lines like...
warn Apache::Script::handler;
And in the config file:
Location /Script
SetHandler perl-script
PerlResponseHandler Apache::Script
/Location
Repeatedly loading the URL I get different results almost every time.
With the first 'warn' statement producing oyutput almst every iteration
and occasionally the later warn statements not being executed, and often
with no output.
Making changes t the script (adding debugging 'warn' statements) are
only reliably (ish) noticed if I restart the server. There is some
unreliability in my code (bugs) I am trying to track down but it is
confounded by the fact I am not sure what mod_perl is doing.
There seems to be a time element. After restarting the server
everything goes well for a while (minutes) but soon behaviour changes
and I am back to only some of the code executing (with no oither changes
but the passing of time).
I thought mod_perl would reload code that changed. Is this wrong?
Worik
--
The only true evil is turning people into things
Granny Weatherwax
worik.stan...@gmail.com 021-1680650, (03) 4821804
Aotearoa (New Zealand)
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Re: Trouble with script execution
No, you have to restart the server for code changes to be noticed.
On May 18, 2014 6:48 PM, Worik Stanton worik.stan...@gmail.com wrote:
I am having a nproblem executing my handler.
The short of it is it is when I make a change to the script I have to
restart the server to get it noticed, and it does not always call the
same code.
The lng of it:
I have a package with a 'handler' function.
It starts...
package Apache::Script;
use strict;
use Apache2::Const qw(:common);
use Apache2::Connection;
[snip]
sub handler {
warn Apache::Script::handler $$ '.join(, , @_).';
my $r = shift;
[snip]
Many more lines like...
warn Apache::Script::handler;
And in the config file:
Location /Script
SetHandler perl-script
PerlResponseHandler Apache::Script
/Location
Repeatedly loading the URL I get different results almost every time.
With the first 'warn' statement producing oyutput almst every iteration
and occasionally the later warn statements not being executed, and often
with no output.
Making changes t the script (adding debugging 'warn' statements) are
only reliably (ish) noticed if I restart the server. There is some
unreliability in my code (bugs) I am trying to track down but it is
confounded by the fact I am not sure what mod_perl is doing.
There seems to be a time element. After restarting the server
everything goes well for a while (minutes) but soon behaviour changes
and I am back to only some of the code executing (with no oither changes
but the passing of time).
I thought mod_perl would reload code that changed. Is this wrong?
Worik
--
The only true evil is turning people into things
Granny Weatherwax
worik.stan...@gmail.com 021-1680650, (03) 4821804
Aotearoa (New Zealand)
What about debugging?
Is there a way to get useful debugging info? I am getting messages like: failed to resolve handler `Apache::AdMachine::MyHandler;' Which says something is wrong, but offers no clue. If I have a bug like: my $z = ; # Clearly wrong I get a useful error message. So when I see: failed to resolve handler `Apache::AdMachine::MyHandler;' I am a bit lost Worik -- The only true evil is turning people into things Granny Weatherwax worik.stan...@gmail.com 021-1680650, (03) 4821804 Aotearoa (New Zealand) signature.asc Description: OpenPGP digital signature
Re: Trouble with script execution
On 19/05/14 11:34, John Dunlap wrote: No, you have to restart the server for code changes to be noticed. Does that mean I have to restart my server for every change to a script? Worik -- The only true evil is turning people into things Granny Weatherwax worik.stan...@gmail.com 021-1680650, (03) 4821804 Aotearoa (New Zealand) signature.asc Description: OpenPGP digital signature
Re: What about debugging?
On 19/05/14 12:03, Worik Stanton wrote: Is there a way to get useful debugging info? I am getting messages like: failed to resolve handler `Apache::AdMachine::MyHandler;' Excuse my sillieness. `Apache::AdMachine::MyHandler;' had a ';' on the end. The error message was very sensible, and I was unobservant, Sorry to waste your time. Worik -- The only true evil is turning people into things Granny Weatherwax worik.stan...@gmail.com 021-1680650, (03) 4821804 Aotearoa (New Zealand) signature.asc Description: OpenPGP digital signature
Re: Trouble with script execution
Yep you need to restart to see your changes. Believe it or not, that's one of the *nice* things about mod_perl. Instead of compiling the code during each execution as PERL does when executed as a purely interpreted language , mod_perl causes each Apache child process to compile the code during it's first request/execution and then caches that compiled version of that code. You will need to restart the web server to clear that cache and force your changes to take effect. This is probably why you're getting inconsistent results after code changes, your seeing some requests that are handled by new child processes that are compiling the latest version of your code and some requests that are being handled by old child processes which are still serving previous versions that they've complied and cached. It may seem inconvenient for you, but this type of caching is a *necessity* when running PERL on any sort of real website that gets an appreciable amount of traffic for performance reasons. There are methods you can employ that tell Apache to automatically reload when it sees code change, pretty easy to find if you dig around the Internet.Although I wouldn't use this in a production system. On 5/18/2014 8:04 PM, Worik Stanton wrote: On 19/05/14 11:34, John Dunlap wrote: No, you have to restart the server for code changes to be noticed. Does that mean I have to restart my server for every change to a script? Worik
Re: API Docs
* André Warnier a...@ice-sa.com wrote: Date: Sat, 17 May 2014 11:59:24 +0200 From: André Warnier a...@ice-sa.com To: mod_perl list modperl@perl.apache.org Subject: Re: API Docs User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) Worik Stanton wrote: On 16/05/14 21:09, André Warnier wrote: Maybe you should start here : https://perl.apache.org/docs/2.0/user/handlers/intro.html#What_are_Handlers_ Thank you. That is very useful Welcome. One thing which you cannot complain about apparently, is the number of answers you're getting. mod_perl advocacy seems alive and well. Don't hesitate to ask if you have further questions. ... I think it was because list mail was being held up somewhere, and people thought nobody had replied. It was interesting to see the variety of responses to the question. :-) I have certainly learnt something from them. Regards, Jie
Re: Trouble with script execution
On 19/05/14 12:13, Brad Van Sickle wrote: Yep you need to restart to see your changes. I am sure I read somewhere that mod_perl monitors scripts and reloads them if the modification date changes. But oh well. It definitely notices sometimes. cheers Worik -- The only true evil is turning people into things Granny Weatherwax worik.stan...@gmail.com 021-1680650, (03) 4821804 Aotearoa (New Zealand) signature.asc Description: OpenPGP digital signature
Re: Trouble with script execution
That hasn't been my experience. I always need to restart the server. One of the challenges with that is that objects can persist in memory between requests because the perl runtime persists between requests. If the script changes, how do you apply those changes to objects instances which already exist in memory? It is not a simple problem and it exists in other languages(java) as well. Entire companies(ZeroTurnaround) have been built around solving this kind of problem. The only reason that you can make changes in a language like php without a server restart is because php objects cannot persist between requests like they can in perl or Java and that approach has its own disadvantages. On May 18, 2014 9:47 PM, Worik Stanton worik.stan...@gmail.com wrote: On 19/05/14 12:13, Brad Van Sickle wrote: Yep you need to restart to see your changes. I am sure I read somewhere that mod_perl monitors scripts and reloads them if the modification date changes. But oh well. It definitely notices sometimes. cheers Worik -- The only true evil is turning people into things Granny Weatherwax worik.stan...@gmail.com 021-1680650, (03) 4821804 Aotearoa (New Zealand)
