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Posted to modperl@perl.apache.org by Tosh Cooey <to...@1200group.com> on 2010/01/26 23:27:45 UTC
302 Redirect not working as expected with PerlCleanupHandler and
Firefox under ModPerl::Registry
So this works almost perfectly... Almost because:
#!/usr/bin/perl
use strict;
use Apache2::Const(); # defines OK
use Apache2::Log(); # defines warn
use Apache2::RequestUtil(); # defines push_handlers
my $r = shift;
$r->push_handlers(PerlCleanupHandler => \&cleanup );
$r->headers_out->set(Location => 'http://...index.pl');
$r->status(Apache2::Const::REDIRECT);
return Apache2::Const::REDIRECT;
sub cleanup {
my ($r) = @_;
$r->warn("Starting cleanup");
foreach my $num (1..5) {
$r->warn("Number is $num");
sleep 2;
}
return Apache2::Const::OK;
}
######## test.pl
It seems if you take the above program and hit it with Firefox (3.5.7
and 3.6) it may take 10 seconds (5 x sleep 2) before Firefox does the
redirect. Safari 4.0.4 seems fine. curl works as well :)
I said "may" above because it's not consistent. If you launch Firefox
fresh and hit the above program it may redirect instantly, but then
subsequent hits will illustrate the delay. I'm also seeing varying
behaviour on a different server that has no Basic Auth, but always the
problem is there.
Can anyone else reproduce this?
Thank-you!
Tosh
mackenna@animalhead.com wrote:
> at(1) is a Unix command to start a process.
> Assuming you're on a Unix/Linux box, type "man at" to get the story.
>
> A cleanup handler is more pleasant than a prostate exam.
>
> You can spend your life waiting for others. Just write a
> routine called "cleanup" and have it do something like
> make a log entry.
>
> use Apache2::Const(); # defines OK
> use Apache2::Log(); # defines warn
> use Apache2::RequestUtil(); # defines push_handlers
> ...
> sub cleanup {
> my ($r) = @_;
> $r->warn("cleanup was here");
> return Apache2::Const::OK;
> }
> Then put a call like the one below in your ModPerl::Registry routine.
> If the log entry shows up in error_log, you're on your way...
>
> Good Luck,
> cmac
>
> P.S. Google doesn't index some sites well.
> Look at http://perl.apache.org/docs/2.0/
> particularly its API link.
>
>
> On Jan 25, 2010, at 5:49 PM, Tosh Cooey wrote:
>
>> Sorry, I couldn't figure out what at(1) meant (or maybe ap(1) which
>> you say below) is that an abbreviation for something?
>>
>> And Perrin saying "cleanup handler" is right up there with "prostate
>> exam" in my list of things to get into, both scare me!
>>
>> Of course at some point a man needs to do both...
>>
>> So... If this magic: $r->push_handlers(PerlCleanupHandler =>
>> \&cleanup); is available in ModPerl::Registry context then I will
>> attempt to force all my forks into early retirement and work the
>> problem out that way.
>>
>> Unfortunately Google doesn't return an easy answer, anybody know this
>> before I spend all day tomorrow in my struggle?
>>
>> Thank-you all again,
>>
>> Tosh
>>
>>
>> mackenna@animalhead.com wrote:
>>> You made no comment on the links I sent you earlier today.
>>> They had lots of good advice. Particularly the first one
>>> suggested not forking the Apache process, but using an
>>> ap(1) call to start a process to do the additional processing.
>>> OK, the ap(1) alternative was a bit light on details.
>>> How about the alternative offered by Perrin Hawkins in the
>>> same thread, of using a cleanup handler to do the follow-up
>>> processing rather than a forked process.
>>> From p. 107 of "mod_per2 User's Guide":
>>> $r->push_handlers(PerlCleanupHandler => \&cleanup);
>>>> print $in->redirect... # to redirect the browser
>>> Now cleanup (which receives $r as its operand) can do
>>> whatever slow stuff you need to, can probably use DBI
>>> without all the pain you have below, and can access the
>>> request to find out what to do.
>>> In some past context you may have learned how to get hold of
>>> a $r to use in these calls, and hopefully you're no longer
>>> scared of $r. But there does remain the question of whether
>>> a ModPerl::Registry module can do such calls.
>>> Hopefully someone who knows can chime in on this.
>>> If not, for me it would be worth the editing of getting the
>>> module out from under ModPerl::Registry and into the "native
>>> mode" of SetHandler modperl.
>>> Best of luck,
>>> cmac
>>> On Jan 25, 2010, at 1:54 PM, Tosh Cooey wrote:
>>>> Ok, then maybe I need to supply some code here to try and get
>>>> clarification:
>>>>
>>>> mailfile.pl
>>>> ###########
>>>> use strict;
>>>> ...
>>>> use POSIX;
>>>>
>>>> #gather needed modules and objects
>>>> my $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>> my $clientOBJ = new ...
>>>> my $userOBJ = new ...
>>>> # All OBJjects have a {DBH} property which is their DB handle
>>>> # I hear I have to disconnect these first, do I have to disconnect ALL?
>>>> $fileOBJ->{DBH}->disconnect;
>>>> $SIG{CHLD} = 'IGNORE';
>>>> my $pid;
>>>> if ($pid = fork) {
>>>> warn "Pid = $pid";
>>>> } elsif (defined $pid) {
>>>> close(STDOUT);
>>>> close(STDIN);
>>>> close(STDERR);
>>>>
>>>> # chdir to /, stops the process from preventing an unmount
>>>> chdir '/' or die "Can't chdir to /: $!";
>>>> # dump our STDIN and STDOUT handles
>>>> open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
>>>> open STDOUT, '>/dev/null' or die "Can't write to /dev/null: $!";
>>>> # redirect for logging
>>>> open STDERR, '>/tmp/stderr' or die "Can't write to /tmp/stderr:
>>>> $!";
>>>> # Prevent locking to apache process
>>>> setsid or die "Can't start a new session: $!";
>>>>
>>>> # Create file download link email
>>>> my $mailSTR = ...
>>>>
>>>> # Send the mail possibly to many people
>>>> foreach my $person (@people) {
>>>> open(MAIL, '|' . &cfg('sendmail_location') . ' -t');
>>>> print MAIL $mailSTR;
>>>> close(MAIL);
>>>> }
>>>>
>>>> # Need to recreate the DBI connection on the $fileOBJ I hear
>>>> $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>
>>>> # Do some SQL to update the $fileOBJ status based on mailout
>>>> $fileOBJ->sql....
>>>>
>>>> # create LOGGING Objects to log stuff
>>>> my $logOBJ = new ...
>>>> $logOBJ->sql...
>>>>
>>>> CORE::exit(0);
>>>> }
>>>>
>>>> print $in->redirect... # For the parent to redirect the browser
>>>>
>>>> # Done.
>>>>
>>>> Is there a glaring mistake in the above?
>>>>
>>>> The parent does no more DB stuff, it just sends a redirect.
>>>>
>>>> This runs under ModPerl::Registry.
>>>>
>>>> I'd like to get at least one thing working tonight, either the
>>>> forking or the DBI, I'll be happy!
>>>>
>>>> Tosh
>>>>
>>>>
>>>>
>>>> Perrin Harkins wrote:
>>>>> On Mon, Jan 25, 2010 at 3:48 PM, Tosh Cooey <to...@1200group.com>
>>>>> wrote:
>>>>>> Thanks Perrin, the forking, my child got a PID of 30033 and then
>>>>>> afterwards
>>>>>> when I checked the processes (ps) for 30033 I see:
>>>>>>
>>>>>> [apache2] <defunct>
>>>>>>
>>>>>> Is that what's supposed to happen?
>>>>> After you call exit? No. It should be gone. That's a zombie
>>>>> process.
>>>>>> That PM thread seems to indicate that I must disconnect every DBH,
>>>>>> not just
>>>>>> the ones that I will use.
>>>>> Either that, or you need to set InactiveDestroy on all of them in the
>>>>> child process. Otherwise, when the child exits, it messes up all of
>>>>> them for the parent.
>>>>>> Are you also suggesting the use of
>>>>>> Parallel::ForkManager for forks?
>>>>> No. The DBI stuff is the same with either.
>>>>> - Perrin
>>>>
>>>> --
>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>>
>> --
>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>
>
--
McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
Re: 302 Redirect not working as expected with PerlCleanupHandler
and Firefox under ModPerl::Registry
Posted by Tosh Cooey <to...@1200group.com>.
Would this problem be any different in a normal CGI context with the
program doing forks? I don't imagine it would be, which is why I see
the ultimate wisdom in spawning an external program to handle
long-running tasks, or just cron something.
Oh well, live and learn.
Tosh
William T wrote:
> Caveat Lector:
>
> Long Cleanups done inline on the Apache children can cause problems.
>
> If you get a situation where the CleanUp takes to long OR you get
> enough traffic to the page(s) which engage the CleanUp then you will
> encounter a tipping point, and soon after your website will be almost
> completely unavailable. This will occur because the Apache Children
> aren't processing requests fast enough to handle the rate at which the
> come in; because they are busy in CleanUp.
>
> The reason I bring this up is encountering the failure is usually a
> catastrophic event. The website is almost always entirely down, and
> workarounds can be hard to come by.
>
> This may or may not apply to you depending on your traffic
> characteristics and how long your cleanup takes, BUT it is something
> you should be aware of.
>
> -wjt
>
--
McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
Re: 302 Redirect not working as expected with PerlCleanupHandler and
Firefox under ModPerl::Registry
Posted by William T <di...@gmail.com>.
Caveat Lector:
Long Cleanups done inline on the Apache children can cause problems.
If you get a situation where the CleanUp takes to long OR you get
enough traffic to the page(s) which engage the CleanUp then you will
encounter a tipping point, and soon after your website will be almost
completely unavailable. This will occur because the Apache Children
aren't processing requests fast enough to handle the rate at which the
come in; because they are busy in CleanUp.
The reason I bring this up is encountering the failure is usually a
catastrophic event. The website is almost always entirely down, and
workarounds can be hard to come by.
This may or may not apply to you depending on your traffic
characteristics and how long your cleanup takes, BUT it is something
you should be aware of.
-wjt
Re: 302 Redirect not working as expected with PerlCleanupHandler and Firefox under ModPerl::Registry
Posted by ma...@animalhead.com.
Just wanted to note that since you've put the CONN_CLOSE in the
redirect code, it's not necessary (nor desirable) to put
> "KeepAlive Off" in apache2.conf
With the CONN_CLOSE call you turn KA off just when you need it to be
off.
So what's the bad news?
cmac
On Jan 27, 2010, at 5:08 AM, Tosh Cooey wrote:
> The good news is that Mr. Mackenna got it! If I set "KeepAlive
> Off" in apache2.conf then it all works fine. Below is a
> functioning long process thingy which works with "KeepAlive On" and
> Firefox. I just hope it works with MSIE ...
>
>
> #!/usr/bin/perl
>
> use strict;
> use Apache2::Const -compile => qw(:conn_keepalive);
> use Apache2::Log(); # defines warn
> use Apache2::RequestUtil(); # defines push_handlers
> use Apache2::Connection();
> use Apache2::RequestRec();
>
> my $r = shift;
> my $c = $r->connection();
> $c->keepalive(Apache2::Const::CONN_CLOSE);
> $r->push_handlers(PerlCleanupHandler => \&cleanup );
>
> $r->err_headers_out->set(Location => 'http://...index.pl');
> $r->status(Apache2::Const::REDIRECT);
> return Apache2::Const::REDIRECT;
>
> sub cleanup {
> my ($r) = @_;
> $r->warn("Starting cleanup");
> foreach my $num (1..5) {
> $r->warn("Number is $num");
> sleep 2;
> }
> return Apache2::Const::OK;
> }
> ####
>
> So, thanks again, and as for the warning from William T., well my
> spin-off processes are maybe 10s-10m long and not a driving
> feature, but I will have to keep my eye on them.
>
> Tosh
>
>
> mackenna@animalhead.com wrote:
>> The warning from William T. made me think to ask:
>> Does your site have "KeepAlive On" in httpd.conf?
>> (If not I can't think of anything to suggest...)
>> If so, try adding this as part of the redirect:
>> use Apache2::Connection();
>> use Apache2::RequestRec();
>> ...
>> my $c = $r->connection();
>> $c->keepalive(Apache2::Const::CONN_CLOSE);
>> This will keep your process (which is about to do a "long"
>> cleanup) from automatically getting the redirected request
>> from the browser.
>> Hopefully the root httpd will know that this "redirecting"
>> child has not finished the complete cycle, and will launch
>> other children if needed to process the redirected request
>> plus any other requests.
>> Of course William is right that if lots of requests are
>> arriving that need such cleanup, and the cleanup really does
>> take a long time on average, you are likely to pile up
>> more children than your household income (I'm sorry I meant
>> to say your server :-) can support.
>> Good Luck,
>> cmac
>> On Jan 26, 2010, at 2:27 PM, Tosh Cooey wrote:
>>> So this works almost perfectly... Almost because:
>>>
>>> #!/usr/bin/perl
>>>
>>> use strict;
>>> use Apache2::Const(); # defines OK
>>> use Apache2::Log(); # defines warn
>>> use Apache2::RequestUtil(); # defines push_handlers
>>>
>>> my $r = shift;
>>> $r->push_handlers(PerlCleanupHandler => \&cleanup );
>>>
>>> $r->headers_out->set(Location => 'http://...index.pl');
>>> $r->status(Apache2::Const::REDIRECT);
>>> return Apache2::Const::REDIRECT;
>>>
>>> sub cleanup {
>>> my ($r) = @_;
>>> $r->warn("Starting cleanup");
>>> foreach my $num (1..5) {
>>> $r->warn("Number is $num");
>>> sleep 2;
>>> }
>>> return Apache2::Const::OK;
>>> }
>>> ######## test.pl
>>>
>>>
>>> It seems if you take the above program and hit it with Firefox
>>> (3.5.7 and 3.6) it may take 10 seconds (5 x sleep 2) before
>>> Firefox does the redirect. Safari 4.0.4 seems fine. curl works
>>> as well :)
>>>
>>> I said "may" above because it's not consistent. If you launch
>>> Firefox fresh and hit the above program it may redirect
>>> instantly, but then subsequent hits will illustrate the delay.
>>> I'm also seeing varying behaviour on a different server that has
>>> no Basic Auth, but always the problem is there.
>>>
>>> Can anyone else reproduce this?
>>>
>>> Thank-you!
>>>
>>> Tosh
>>>
>>>
>>> mackenna@animalhead.com wrote:
>>>> at(1) is a Unix command to start a process.
>>>> Assuming you're on a Unix/Linux box, type "man at" to get the
>>>> story.
>>>> A cleanup handler is more pleasant than a prostate exam.
>>>> You can spend your life waiting for others. Just write a
>>>> routine called "cleanup" and have it do something like
>>>> make a log entry.
>>>> use Apache2::Const(); # defines OK
>>>> use Apache2::Log(); # defines warn
>>>> use Apache2::RequestUtil(); # defines push_handlers
>>>> ...
>>>> sub cleanup {
>>>> my ($r) = @_;
>>>> $r->warn("cleanup was here");
>>>> return Apache2::Const::OK;
>>>> }
>>>> Then put a call like the one below in your ModPerl::Registry
>>>> routine.
>>>> If the log entry shows up in error_log, you're on your way...
>>>> Good Luck,
>>>> cmac
>>>> P.S. Google doesn't index some sites well.
>>>> Look at http://perl.apache.org/docs/2.0/
>>>> particularly its API link.
>>>> On Jan 25, 2010, at 5:49 PM, Tosh Cooey wrote:
>>>>> Sorry, I couldn't figure out what at(1) meant (or maybe ap(1)
>>>>> which you say below) is that an abbreviation for something?
>>>>>
>>>>> And Perrin saying "cleanup handler" is right up there with
>>>>> "prostate exam" in my list of things to get into, both scare me!
>>>>>
>>>>> Of course at some point a man needs to do both...
>>>>>
>>>>> So... If this magic: $r->push_handlers(PerlCleanupHandler =>
>>>>> \&cleanup); is available in ModPerl::Registry context then I
>>>>> will attempt to force all my forks into early retirement and
>>>>> work the problem out that way.
>>>>>
>>>>> Unfortunately Google doesn't return an easy answer, anybody
>>>>> know this before I spend all day tomorrow in my struggle?
>>>>>
>>>>> Thank-you all again,
>>>>>
>>>>> Tosh
>>>>>
>>>>>
>>>>> mackenna@animalhead.com wrote:
>>>>>> You made no comment on the links I sent you earlier today.
>>>>>> They had lots of good advice. Particularly the first one
>>>>>> suggested not forking the Apache process, but using an
>>>>>> ap(1) call to start a process to do the additional processing.
>>>>>> OK, the ap(1) alternative was a bit light on details.
>>>>>> How about the alternative offered by Perrin Hawkins in the
>>>>>> same thread, of using a cleanup handler to do the follow-up
>>>>>> processing rather than a forked process.
>>>>>> From p. 107 of "mod_per2 User's Guide":
>>>>>> $r->push_handlers(PerlCleanupHandler => \&cleanup);
>>>>>>> print $in->redirect... # to redirect the browser
>>>>>> Now cleanup (which receives $r as its operand) can do
>>>>>> whatever slow stuff you need to, can probably use DBI
>>>>>> without all the pain you have below, and can access the
>>>>>> request to find out what to do.
>>>>>> In some past context you may have learned how to get hold of
>>>>>> a $r to use in these calls, and hopefully you're no longer
>>>>>> scared of $r. But there does remain the question of whether
>>>>>> a ModPerl::Registry module can do such calls.
>>>>>> Hopefully someone who knows can chime in on this.
>>>>>> If not, for me it would be worth the editing of getting the
>>>>>> module out from under ModPerl::Registry and into the "native
>>>>>> mode" of SetHandler modperl.
>>>>>> Best of luck,
>>>>>> cmac
>>>>>> On Jan 25, 2010, at 1:54 PM, Tosh Cooey wrote:
>>>>>>> Ok, then maybe I need to supply some code here to try and get
>>>>>>> clarification:
>>>>>>>
>>>>>>> mailfile.pl
>>>>>>> ###########
>>>>>>> use strict;
>>>>>>> ...
>>>>>>> use POSIX;
>>>>>>>
>>>>>>> #gather needed modules and objects
>>>>>>> my $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>>>> my $clientOBJ = new ...
>>>>>>> my $userOBJ = new ...
>>>>>>> # All OBJjects have a {DBH} property which is their DB handle
>>>>>>> # I hear I have to disconnect these first, do I have to
>>>>>>> disconnect ALL?
>>>>>>> $fileOBJ->{DBH}->disconnect;
>>>>>>> $SIG{CHLD} = 'IGNORE';
>>>>>>> my $pid;
>>>>>>> if ($pid = fork) {
>>>>>>> warn "Pid = $pid";
>>>>>>> } elsif (defined $pid) {
>>>>>>> close(STDOUT);
>>>>>>> close(STDIN);
>>>>>>> close(STDERR);
>>>>>>>
>>>>>>> # chdir to /, stops the process from preventing an unmount
>>>>>>> chdir '/' or die "Can't chdir to /: $!";
>>>>>>> # dump our STDIN and STDOUT handles
>>>>>>> open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
>>>>>>> open STDOUT, '>/dev/null' or die "Can't write to /dev/
>>>>>>> null: $!";
>>>>>>> # redirect for logging
>>>>>>> open STDERR, '>/tmp/stderr' or die "Can't write to /tmp/
>>>>>>> stderr: $!";
>>>>>>> # Prevent locking to apache process
>>>>>>> setsid or die "Can't start a new session: $!";
>>>>>>>
>>>>>>> # Create file download link email
>>>>>>> my $mailSTR = ...
>>>>>>>
>>>>>>> # Send the mail possibly to many people
>>>>>>> foreach my $person (@people) {
>>>>>>> open(MAIL, '|' . &cfg('sendmail_location') . ' -t');
>>>>>>> print MAIL $mailSTR;
>>>>>>> close(MAIL);
>>>>>>> }
>>>>>>>
>>>>>>> # Need to recreate the DBI connection on the $fileOBJ I hear
>>>>>>> $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>>>>
>>>>>>> # Do some SQL to update the $fileOBJ status based on mailout
>>>>>>> $fileOBJ->sql....
>>>>>>>
>>>>>>> # create LOGGING Objects to log stuff
>>>>>>> my $logOBJ = new ...
>>>>>>> $logOBJ->sql...
>>>>>>>
>>>>>>> CORE::exit(0);
>>>>>>> }
>>>>>>>
>>>>>>> print $in->redirect... # For the parent to redirect the browser
>>>>>>>
>>>>>>> # Done.
>>>>>>>
>>>>>>> Is there a glaring mistake in the above?
>>>>>>>
>>>>>>> The parent does no more DB stuff, it just sends a redirect.
>>>>>>>
>>>>>>> This runs under ModPerl::Registry.
>>>>>>>
>>>>>>> I'd like to get at least one thing working tonight, either
>>>>>>> the forking or the DBI, I'll be happy!
>>>>>>>
>>>>>>> Tosh
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Perrin Harkins wrote:
>>>>>>>> On Mon, Jan 25, 2010 at 3:48 PM, Tosh Cooey
>>>>>>>> <to...@1200group.com> wrote:
>>>>>>>>> Thanks Perrin, the forking, my child got a PID of 30033 and
>>>>>>>>> then afterwards
>>>>>>>>> when I checked the processes (ps) for 30033 I see:
>>>>>>>>>
>>>>>>>>> [apache2] <defunct>
>>>>>>>>>
>>>>>>>>> Is that what's supposed to happen?
>>>>>>>> After you call exit? No. It should be gone. That's a
>>>>>>>> zombie process.
>>>>>>>>> That PM thread seems to indicate that I must disconnect
>>>>>>>>> every DBH, not just
>>>>>>>>> the ones that I will use.
>>>>>>>> Either that, or you need to set InactiveDestroy on all of
>>>>>>>> them in the
>>>>>>>> child process. Otherwise, when the child exits, it messes
>>>>>>>> up all of
>>>>>>>> them for the parent.
>>>>>>>>> Are you also suggesting the use of
>>>>>>>>> Parallel::ForkManager for forks?
>>>>>>>> No. The DBI stuff is the same with either.
>>>>>>>> - Perrin
>>>>>>>
>>>>>>> --
>>>>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.
>>>>>>> 1200group.com/
>>>>>
>>>>> --
>>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.
>>>>> 1200group.com/
>>>
>>> --
>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.
>>> 1200group.com/
>
> --
> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
Re: 302 Redirect not working as expected with PerlCleanupHandler
and Firefox under ModPerl::Registry
Posted by Tosh Cooey <to...@1200group.com>.
The good news is that Mr. Mackenna got it! If I set "KeepAlive Off" in
apache2.conf then it all works fine. Below is a functioning long
process thingy which works with "KeepAlive On" and Firefox. I just hope
it works with MSIE ...
#!/usr/bin/perl
use strict;
use Apache2::Const -compile => qw(:conn_keepalive);
use Apache2::Log(); # defines warn
use Apache2::RequestUtil(); # defines push_handlers
use Apache2::Connection();
use Apache2::RequestRec();
my $r = shift;
my $c = $r->connection();
$c->keepalive(Apache2::Const::CONN_CLOSE);
$r->push_handlers(PerlCleanupHandler => \&cleanup );
$r->err_headers_out->set(Location => 'http://...index.pl');
$r->status(Apache2::Const::REDIRECT);
return Apache2::Const::REDIRECT;
sub cleanup {
my ($r) = @_;
$r->warn("Starting cleanup");
foreach my $num (1..5) {
$r->warn("Number is $num");
sleep 2;
}
return Apache2::Const::OK;
}
####
So, thanks again, and as for the warning from William T., well my
spin-off processes are maybe 10s-10m long and not a driving feature, but
I will have to keep my eye on them.
Tosh
mackenna@animalhead.com wrote:
> The warning from William T. made me think to ask:
>
> Does your site have "KeepAlive On" in httpd.conf?
> (If not I can't think of anything to suggest...)
>
> If so, try adding this as part of the redirect:
>
> use Apache2::Connection();
> use Apache2::RequestRec();
> ...
> my $c = $r->connection();
> $c->keepalive(Apache2::Const::CONN_CLOSE);
>
> This will keep your process (which is about to do a "long"
> cleanup) from automatically getting the redirected request
> from the browser.
>
> Hopefully the root httpd will know that this "redirecting"
> child has not finished the complete cycle, and will launch
> other children if needed to process the redirected request
> plus any other requests.
>
> Of course William is right that if lots of requests are
> arriving that need such cleanup, and the cleanup really does
> take a long time on average, you are likely to pile up
> more children than your household income (I'm sorry I meant
> to say your server :-) can support.
>
> Good Luck,
> cmac
>
>
> On Jan 26, 2010, at 2:27 PM, Tosh Cooey wrote:
>
>> So this works almost perfectly... Almost because:
>>
>> #!/usr/bin/perl
>>
>> use strict;
>> use Apache2::Const(); # defines OK
>> use Apache2::Log(); # defines warn
>> use Apache2::RequestUtil(); # defines push_handlers
>>
>> my $r = shift;
>> $r->push_handlers(PerlCleanupHandler => \&cleanup );
>>
>> $r->headers_out->set(Location => 'http://...index.pl');
>> $r->status(Apache2::Const::REDIRECT);
>> return Apache2::Const::REDIRECT;
>>
>> sub cleanup {
>> my ($r) = @_;
>> $r->warn("Starting cleanup");
>> foreach my $num (1..5) {
>> $r->warn("Number is $num");
>> sleep 2;
>> }
>> return Apache2::Const::OK;
>> }
>> ######## test.pl
>>
>>
>> It seems if you take the above program and hit it with Firefox (3.5.7
>> and 3.6) it may take 10 seconds (5 x sleep 2) before Firefox does the
>> redirect. Safari 4.0.4 seems fine. curl works as well :)
>>
>> I said "may" above because it's not consistent. If you launch Firefox
>> fresh and hit the above program it may redirect instantly, but then
>> subsequent hits will illustrate the delay. I'm also seeing varying
>> behaviour on a different server that has no Basic Auth, but always the
>> problem is there.
>>
>> Can anyone else reproduce this?
>>
>> Thank-you!
>>
>> Tosh
>>
>>
>> mackenna@animalhead.com wrote:
>>> at(1) is a Unix command to start a process.
>>> Assuming you're on a Unix/Linux box, type "man at" to get the story.
>>> A cleanup handler is more pleasant than a prostate exam.
>>> You can spend your life waiting for others. Just write a
>>> routine called "cleanup" and have it do something like
>>> make a log entry.
>>> use Apache2::Const(); # defines OK
>>> use Apache2::Log(); # defines warn
>>> use Apache2::RequestUtil(); # defines push_handlers
>>> ...
>>> sub cleanup {
>>> my ($r) = @_;
>>> $r->warn("cleanup was here");
>>> return Apache2::Const::OK;
>>> }
>>> Then put a call like the one below in your ModPerl::Registry routine.
>>> If the log entry shows up in error_log, you're on your way...
>>> Good Luck,
>>> cmac
>>> P.S. Google doesn't index some sites well.
>>> Look at http://perl.apache.org/docs/2.0/
>>> particularly its API link.
>>> On Jan 25, 2010, at 5:49 PM, Tosh Cooey wrote:
>>>> Sorry, I couldn't figure out what at(1) meant (or maybe ap(1) which
>>>> you say below) is that an abbreviation for something?
>>>>
>>>> And Perrin saying "cleanup handler" is right up there with "prostate
>>>> exam" in my list of things to get into, both scare me!
>>>>
>>>> Of course at some point a man needs to do both...
>>>>
>>>> So... If this magic: $r->push_handlers(PerlCleanupHandler =>
>>>> \&cleanup); is available in ModPerl::Registry context then I will
>>>> attempt to force all my forks into early retirement and work the
>>>> problem out that way.
>>>>
>>>> Unfortunately Google doesn't return an easy answer, anybody know
>>>> this before I spend all day tomorrow in my struggle?
>>>>
>>>> Thank-you all again,
>>>>
>>>> Tosh
>>>>
>>>>
>>>> mackenna@animalhead.com wrote:
>>>>> You made no comment on the links I sent you earlier today.
>>>>> They had lots of good advice. Particularly the first one
>>>>> suggested not forking the Apache process, but using an
>>>>> ap(1) call to start a process to do the additional processing.
>>>>> OK, the ap(1) alternative was a bit light on details.
>>>>> How about the alternative offered by Perrin Hawkins in the
>>>>> same thread, of using a cleanup handler to do the follow-up
>>>>> processing rather than a forked process.
>>>>> From p. 107 of "mod_per2 User's Guide":
>>>>> $r->push_handlers(PerlCleanupHandler => \&cleanup);
>>>>>> print $in->redirect... # to redirect the browser
>>>>> Now cleanup (which receives $r as its operand) can do
>>>>> whatever slow stuff you need to, can probably use DBI
>>>>> without all the pain you have below, and can access the
>>>>> request to find out what to do.
>>>>> In some past context you may have learned how to get hold of
>>>>> a $r to use in these calls, and hopefully you're no longer
>>>>> scared of $r. But there does remain the question of whether
>>>>> a ModPerl::Registry module can do such calls.
>>>>> Hopefully someone who knows can chime in on this.
>>>>> If not, for me it would be worth the editing of getting the
>>>>> module out from under ModPerl::Registry and into the "native
>>>>> mode" of SetHandler modperl.
>>>>> Best of luck,
>>>>> cmac
>>>>> On Jan 25, 2010, at 1:54 PM, Tosh Cooey wrote:
>>>>>> Ok, then maybe I need to supply some code here to try and get
>>>>>> clarification:
>>>>>>
>>>>>> mailfile.pl
>>>>>> ###########
>>>>>> use strict;
>>>>>> ...
>>>>>> use POSIX;
>>>>>>
>>>>>> #gather needed modules and objects
>>>>>> my $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>>> my $clientOBJ = new ...
>>>>>> my $userOBJ = new ...
>>>>>> # All OBJjects have a {DBH} property which is their DB handle
>>>>>> # I hear I have to disconnect these first, do I have to disconnect
>>>>>> ALL?
>>>>>> $fileOBJ->{DBH}->disconnect;
>>>>>> $SIG{CHLD} = 'IGNORE';
>>>>>> my $pid;
>>>>>> if ($pid = fork) {
>>>>>> warn "Pid = $pid";
>>>>>> } elsif (defined $pid) {
>>>>>> close(STDOUT);
>>>>>> close(STDIN);
>>>>>> close(STDERR);
>>>>>>
>>>>>> # chdir to /, stops the process from preventing an unmount
>>>>>> chdir '/' or die "Can't chdir to /: $!";
>>>>>> # dump our STDIN and STDOUT handles
>>>>>> open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
>>>>>> open STDOUT, '>/dev/null' or die "Can't write to /dev/null: $!";
>>>>>> # redirect for logging
>>>>>> open STDERR, '>/tmp/stderr' or die "Can't write to
>>>>>> /tmp/stderr: $!";
>>>>>> # Prevent locking to apache process
>>>>>> setsid or die "Can't start a new session: $!";
>>>>>>
>>>>>> # Create file download link email
>>>>>> my $mailSTR = ...
>>>>>>
>>>>>> # Send the mail possibly to many people
>>>>>> foreach my $person (@people) {
>>>>>> open(MAIL, '|' . &cfg('sendmail_location') . ' -t');
>>>>>> print MAIL $mailSTR;
>>>>>> close(MAIL);
>>>>>> }
>>>>>>
>>>>>> # Need to recreate the DBI connection on the $fileOBJ I hear
>>>>>> $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>>>
>>>>>> # Do some SQL to update the $fileOBJ status based on mailout
>>>>>> $fileOBJ->sql....
>>>>>>
>>>>>> # create LOGGING Objects to log stuff
>>>>>> my $logOBJ = new ...
>>>>>> $logOBJ->sql...
>>>>>>
>>>>>> CORE::exit(0);
>>>>>> }
>>>>>>
>>>>>> print $in->redirect... # For the parent to redirect the browser
>>>>>>
>>>>>> # Done.
>>>>>>
>>>>>> Is there a glaring mistake in the above?
>>>>>>
>>>>>> The parent does no more DB stuff, it just sends a redirect.
>>>>>>
>>>>>> This runs under ModPerl::Registry.
>>>>>>
>>>>>> I'd like to get at least one thing working tonight, either the
>>>>>> forking or the DBI, I'll be happy!
>>>>>>
>>>>>> Tosh
>>>>>>
>>>>>>
>>>>>>
>>>>>> Perrin Harkins wrote:
>>>>>>> On Mon, Jan 25, 2010 at 3:48 PM, Tosh Cooey <to...@1200group.com>
>>>>>>> wrote:
>>>>>>>> Thanks Perrin, the forking, my child got a PID of 30033 and then
>>>>>>>> afterwards
>>>>>>>> when I checked the processes (ps) for 30033 I see:
>>>>>>>>
>>>>>>>> [apache2] <defunct>
>>>>>>>>
>>>>>>>> Is that what's supposed to happen?
>>>>>>> After you call exit? No. It should be gone. That's a zombie
>>>>>>> process.
>>>>>>>> That PM thread seems to indicate that I must disconnect every
>>>>>>>> DBH, not just
>>>>>>>> the ones that I will use.
>>>>>>> Either that, or you need to set InactiveDestroy on all of them in
>>>>>>> the
>>>>>>> child process. Otherwise, when the child exits, it messes up all of
>>>>>>> them for the parent.
>>>>>>>> Are you also suggesting the use of
>>>>>>>> Parallel::ForkManager for forks?
>>>>>>> No. The DBI stuff is the same with either.
>>>>>>> - Perrin
>>>>>>
>>>>>> --
>>>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>>>>
>>>> --
>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>>
>> --
>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>
>
--
McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
Re: 302 Redirect not working as expected with PerlCleanupHandler and Firefox under ModPerl::Registry
Posted by ma...@animalhead.com.
The warning from William T. made me think to ask:
Does your site have "KeepAlive On" in httpd.conf?
(If not I can't think of anything to suggest...)
If so, try adding this as part of the redirect:
use Apache2::Connection();
use Apache2::RequestRec();
...
my $c = $r->connection();
$c->keepalive(Apache2::Const::CONN_CLOSE);
This will keep your process (which is about to do a "long"
cleanup) from automatically getting the redirected request
from the browser.
Hopefully the root httpd will know that this "redirecting"
child has not finished the complete cycle, and will launch
other children if needed to process the redirected request
plus any other requests.
Of course William is right that if lots of requests are
arriving that need such cleanup, and the cleanup really does
take a long time on average, you are likely to pile up
more children than your household income (I'm sorry I meant
to say your server :-) can support.
Good Luck,
cmac
On Jan 26, 2010, at 2:27 PM, Tosh Cooey wrote:
> So this works almost perfectly... Almost because:
>
> #!/usr/bin/perl
>
> use strict;
> use Apache2::Const(); # defines OK
> use Apache2::Log(); # defines warn
> use Apache2::RequestUtil(); # defines push_handlers
>
> my $r = shift;
> $r->push_handlers(PerlCleanupHandler => \&cleanup );
>
> $r->headers_out->set(Location => 'http://...index.pl');
> $r->status(Apache2::Const::REDIRECT);
> return Apache2::Const::REDIRECT;
>
> sub cleanup {
> my ($r) = @_;
> $r->warn("Starting cleanup");
> foreach my $num (1..5) {
> $r->warn("Number is $num");
> sleep 2;
> }
> return Apache2::Const::OK;
> }
> ######## test.pl
>
>
> It seems if you take the above program and hit it with Firefox
> (3.5.7 and 3.6) it may take 10 seconds (5 x sleep 2) before Firefox
> does the redirect. Safari 4.0.4 seems fine. curl works as well :)
>
> I said "may" above because it's not consistent. If you launch
> Firefox fresh and hit the above program it may redirect instantly,
> but then subsequent hits will illustrate the delay. I'm also
> seeing varying behaviour on a different server that has no Basic
> Auth, but always the problem is there.
>
> Can anyone else reproduce this?
>
> Thank-you!
>
> Tosh
>
>
> mackenna@animalhead.com wrote:
>> at(1) is a Unix command to start a process.
>> Assuming you're on a Unix/Linux box, type "man at" to get the story.
>> A cleanup handler is more pleasant than a prostate exam.
>> You can spend your life waiting for others. Just write a
>> routine called "cleanup" and have it do something like
>> make a log entry.
>> use Apache2::Const(); # defines OK
>> use Apache2::Log(); # defines warn
>> use Apache2::RequestUtil(); # defines push_handlers
>> ...
>> sub cleanup {
>> my ($r) = @_;
>> $r->warn("cleanup was here");
>> return Apache2::Const::OK;
>> }
>> Then put a call like the one below in your ModPerl::Registry routine.
>> If the log entry shows up in error_log, you're on your way...
>> Good Luck,
>> cmac
>> P.S. Google doesn't index some sites well.
>> Look at http://perl.apache.org/docs/2.0/
>> particularly its API link.
>> On Jan 25, 2010, at 5:49 PM, Tosh Cooey wrote:
>>> Sorry, I couldn't figure out what at(1) meant (or maybe ap(1)
>>> which you say below) is that an abbreviation for something?
>>>
>>> And Perrin saying "cleanup handler" is right up there with
>>> "prostate exam" in my list of things to get into, both scare me!
>>>
>>> Of course at some point a man needs to do both...
>>>
>>> So... If this magic: $r->push_handlers(PerlCleanupHandler =>
>>> \&cleanup); is available in ModPerl::Registry context then I will
>>> attempt to force all my forks into early retirement and work the
>>> problem out that way.
>>>
>>> Unfortunately Google doesn't return an easy answer, anybody know
>>> this before I spend all day tomorrow in my struggle?
>>>
>>> Thank-you all again,
>>>
>>> Tosh
>>>
>>>
>>> mackenna@animalhead.com wrote:
>>>> You made no comment on the links I sent you earlier today.
>>>> They had lots of good advice. Particularly the first one
>>>> suggested not forking the Apache process, but using an
>>>> ap(1) call to start a process to do the additional processing.
>>>> OK, the ap(1) alternative was a bit light on details.
>>>> How about the alternative offered by Perrin Hawkins in the
>>>> same thread, of using a cleanup handler to do the follow-up
>>>> processing rather than a forked process.
>>>> From p. 107 of "mod_per2 User's Guide":
>>>> $r->push_handlers(PerlCleanupHandler => \&cleanup);
>>>>> print $in->redirect... # to redirect the browser
>>>> Now cleanup (which receives $r as its operand) can do
>>>> whatever slow stuff you need to, can probably use DBI
>>>> without all the pain you have below, and can access the
>>>> request to find out what to do.
>>>> In some past context you may have learned how to get hold of
>>>> a $r to use in these calls, and hopefully you're no longer
>>>> scared of $r. But there does remain the question of whether
>>>> a ModPerl::Registry module can do such calls.
>>>> Hopefully someone who knows can chime in on this.
>>>> If not, for me it would be worth the editing of getting the
>>>> module out from under ModPerl::Registry and into the "native
>>>> mode" of SetHandler modperl.
>>>> Best of luck,
>>>> cmac
>>>> On Jan 25, 2010, at 1:54 PM, Tosh Cooey wrote:
>>>>> Ok, then maybe I need to supply some code here to try and get
>>>>> clarification:
>>>>>
>>>>> mailfile.pl
>>>>> ###########
>>>>> use strict;
>>>>> ...
>>>>> use POSIX;
>>>>>
>>>>> #gather needed modules and objects
>>>>> my $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>> my $clientOBJ = new ...
>>>>> my $userOBJ = new ...
>>>>> # All OBJjects have a {DBH} property which is their DB handle
>>>>> # I hear I have to disconnect these first, do I have to
>>>>> disconnect ALL?
>>>>> $fileOBJ->{DBH}->disconnect;
>>>>> $SIG{CHLD} = 'IGNORE';
>>>>> my $pid;
>>>>> if ($pid = fork) {
>>>>> warn "Pid = $pid";
>>>>> } elsif (defined $pid) {
>>>>> close(STDOUT);
>>>>> close(STDIN);
>>>>> close(STDERR);
>>>>>
>>>>> # chdir to /, stops the process from preventing an unmount
>>>>> chdir '/' or die "Can't chdir to /: $!";
>>>>> # dump our STDIN and STDOUT handles
>>>>> open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
>>>>> open STDOUT, '>/dev/null' or die "Can't write to /dev/null:
>>>>> $!";
>>>>> # redirect for logging
>>>>> open STDERR, '>/tmp/stderr' or die "Can't write to /tmp/
>>>>> stderr: $!";
>>>>> # Prevent locking to apache process
>>>>> setsid or die "Can't start a new session: $!";
>>>>>
>>>>> # Create file download link email
>>>>> my $mailSTR = ...
>>>>>
>>>>> # Send the mail possibly to many people
>>>>> foreach my $person (@people) {
>>>>> open(MAIL, '|' . &cfg('sendmail_location') . ' -t');
>>>>> print MAIL $mailSTR;
>>>>> close(MAIL);
>>>>> }
>>>>>
>>>>> # Need to recreate the DBI connection on the $fileOBJ I hear
>>>>> $fileOBJ = new MyOBJS::FILE($in->param('id'));
>>>>>
>>>>> # Do some SQL to update the $fileOBJ status based on mailout
>>>>> $fileOBJ->sql....
>>>>>
>>>>> # create LOGGING Objects to log stuff
>>>>> my $logOBJ = new ...
>>>>> $logOBJ->sql...
>>>>>
>>>>> CORE::exit(0);
>>>>> }
>>>>>
>>>>> print $in->redirect... # For the parent to redirect the browser
>>>>>
>>>>> # Done.
>>>>>
>>>>> Is there a glaring mistake in the above?
>>>>>
>>>>> The parent does no more DB stuff, it just sends a redirect.
>>>>>
>>>>> This runs under ModPerl::Registry.
>>>>>
>>>>> I'd like to get at least one thing working tonight, either the
>>>>> forking or the DBI, I'll be happy!
>>>>>
>>>>> Tosh
>>>>>
>>>>>
>>>>>
>>>>> Perrin Harkins wrote:
>>>>>> On Mon, Jan 25, 2010 at 3:48 PM, Tosh Cooey
>>>>>> <to...@1200group.com> wrote:
>>>>>>> Thanks Perrin, the forking, my child got a PID of 30033 and
>>>>>>> then afterwards
>>>>>>> when I checked the processes (ps) for 30033 I see:
>>>>>>>
>>>>>>> [apache2] <defunct>
>>>>>>>
>>>>>>> Is that what's supposed to happen?
>>>>>> After you call exit? No. It should be gone. That's a zombie
>>>>>> process.
>>>>>>> That PM thread seems to indicate that I must disconnect every
>>>>>>> DBH, not just
>>>>>>> the ones that I will use.
>>>>>> Either that, or you need to set InactiveDestroy on all of them
>>>>>> in the
>>>>>> child process. Otherwise, when the child exits, it messes up
>>>>>> all of
>>>>>> them for the parent.
>>>>>>> Are you also suggesting the use of
>>>>>>> Parallel::ForkManager for forks?
>>>>>> No. The DBI stuff is the same with either.
>>>>>> - Perrin
>>>>>
>>>>> --
>>>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.
>>>>> 1200group.com/
>>>
>>> --
>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.
>>> 1200group.com/
>
> --
> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/