Trying to detect client dropping connection before CGI process is

Trying to detect client dropping connection before CGI process is

am 22.10.2009 00:18:15 von Fi Dot

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Dear All,





I seem to be completely stuck with trying to detect client dropping
connection, no matter how hard I try.



I start with a simple Perl script running as a standard CGI app:



#!/usr/bin/perl



use strict;



Log("$$: starting process");



$SIG{PIPE} =3D sub { Log("$$: PIPE!!"); };

$SIG{TERM} =3D sub { Log("$$: TERM!!"); };

$SIG{HUP} =3D sub { Log("$$: HUP"); };

$SIG{INT} =3D sub { Log("$$: INT"); };



Log("$$: Processing request");



print "\n\n";



for(1 .. 10)

{

Log("$$: Sleep $_ ");

sleep(1);

}



print "Content\n";



Log("$$: Done");





I also have tried the following modification of the script for mod_perl:





#!/usr/bin/perl



use strict;



use Apache2::RequestRec;

use Apache2::Connection;



Log("$$: starting process");



$SIG{PIPE} =3D sub { Log("$$: PIPE!!"); };

$SIG{TERM} =3D sub { Log("$$: TERM!!"); };

$SIG{HUP} =3D sub { Log("$$: HUP"); };

$SIG{INT} =3D sub { Log("$$: INT"); };



local our $Conn =3D Apache2::RequestRec->connection();



Log("$$: Processing request");



print "\n\n";



for(1 .. 10)

{

Log("$$: Sleep $_, aborted:", $Conn->aborted());

sleep(1);

}



print "Content\n";



Log("$$: Done");





and another modification for mod_fcgid (same idea with trying to intercept
signals and both with and w/o trying to use Apache2::Connection).



Log() function just outputs messages to a log file, that i am tail -f 'ing.





I make a request using curl,



curl http://localhost/script.pl



and also have tried LWP::UserAgent.



The way I test it is run the request process (either curl or a simple .pl
with a request made via LWP::UserAgent), and Control-C at some point (while
watching 'Sleep XX' messages appear in the log file).



In all three cases with both LWP and curl i see the same behavior - no
indication of a client dropping the connection (even with aborted() method
of mod_perl) whatsoever, no signals, no messages about client dropping
connection appearing in error.log of the server (LogLevel is set to 'info')=
,
etc. The CGI process in CGI case doesn't get terminated and / or killed; it
continues to loop and sleep until 10 seconds pass.





From what I have been able to find, I tried:



* Looks like adding print STDOUT in the loop should cause PIPE signal
('broken pipe'), I tried adding 'print STDOUT " "' right before sleep() cal=
l
in the loop with no luck.

* Trying to see if the same print before sleep() would return failure
('print STDOUT " " or Log("Print failed!")', w/o any luck

* In mod_perl tests, trying to use Apache2::RequestRec->print() instead of
print.

* LogLevel info should be giving me messages about clients dropping
connections in error.log. I am not seeing any.





In addition, I clearly recall solving the same problem under mod_perl and
Apache using $Conn->aborted() method, and it worked (but that was a
different version of Apache 2 and mod_perl, unfortunately, I donâ€=99t =
have that
env right now to compareâ€=A6).



I have tried this on 2 versions of Apache and mod_perl,



* Ubuntu + apache 2.2.8 / mod_perl 2.0.3:



root@vmubuntu ~/api # apache2 -V

Server version: Apache/2.2.8 (Ubuntu)

Server built: Feb 2 2008 04:03:01

Server's Module Magic Number: 20051115:11

Server loaded: APR 1.2.11, APR-Util 1.2.12

Compiled using: APR 1.2.11, APR-Util 1.2.12

Architecture: 32-bit

Server MPM: Prefork

threaded: no

forked: yes (variable process count)

Server compiled with....

-D APACHE_MPM_DIR=3D"server/mpm/prefork"

-D APR_HAS_SENDFILE

-D APR_HAS_MMAP

-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)

-D APR_USE_SYSVSEM_SERIALIZE

-D APR_USE_PTHREAD_SERIALIZE

-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT

-D APR_HAS_OTHER_CHILD

-D AP_HAVE_RELIABLE_PIPED_LOGS

-D DYNAMIC_MODULE_LIMIT=3D128

-D HTTPD_ROOT=3D""

-D SUEXEC_BIN=3D"/usr/lib/apache2/suexec"

-D DEFAULT_PIDLOG=3D"/var/run/apache2.pid"

-D DEFAULT_SCOREBOARD=3D"logs/apache_runtime_status"

-D DEFAULT_LOCKFILE=3D"/var/run/apache2/accept.lock"

-D DEFAULT_ERRORLOG=3D"logs/error_log"

-D AP_TYPES_CONFIG_FILE=3D"/etc/apache2/mime.types"

-D SERVER_CONFIG_FILE=3D"/etc/apache2/apache2.conf"



* Gentoo + apache 2.2.11 + mod_perl 2.0.4:



newcore tmp # apache2 -V

Server version: Apache/2.2.11 (Unix)

Server built: Oct 21 2009 16:42:25

Server's Module Magic Number: 20051115:21

Server loaded: APR 1.2.8, APR-Util 1.2.8

Compiled using: APR 1.2.8, APR-Util 1.2.8

Architecture: 32-bit

Server MPM: Prefork

threaded: no

forked: yes (variable process count)

Server compiled with....

-D APACHE_MPM_DIR=3D"server/mpm/prefork"

-D APR_HAS_SENDFILE

-D APR_HAS_MMAP

-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)

-D APR_USE_SYSVSEM_SERIALIZE

-D APR_USE_PTHREAD_SERIALIZE

-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT

-D APR_HAS_OTHER_CHILD

-D AP_HAVE_RELIABLE_PIPED_LOGS

-D DYNAMIC_MODULE_LIMIT=3D128

-D HTTPD_ROOT=3D"/usr"

-D SUEXEC_BIN=3D"/usr/sbin/suexec"

-D DEFAULT_PIDLOG=3D"/var/run/httpd.pid"

-D DEFAULT_SCOREBOARD=3D"logs/apache_runtime_status"

-D DEFAULT_LOCKFILE=3D"/var/run/accept.lock"

-D DEFAULT_ERRORLOG=3D"logs/error_log"

-D AP_TYPES_CONFIG_FILE=3D"/etc/apache2/mime.types"

-D SERVER_CONFIG_FILE=3D"/etc/apache2/httpd.conf"







As you can see, both servers are running prefork mpm.

Would anyone have a suggestion for this problem? Ideally I would like
either to be able to somehow detect client dropping connection from his sid=
e
from within the script, or Apache itself just killing the worker / CGI
process whenever it detects that.


Fi.

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Dear All,



 



 



I seem to be completely stuck with trying to detect =
client
dropping connection, no matter how hard I try.



 



I start with a simple Perl script running as a stand=
ard CGI
app:



 



   #!/usr/bin/perl=



 



   use strict;



 



   Log("$$:
starting process");



 



   $SIG{PIPE} =3D =
sub {
Log("$$: PIPE!!"); };



   $SIG{TERM} =3D =
sub {
Log("$$: TERM!!");  };



   $SIG{HUP} =3D s=
ub {
Log("$$: HUP"); };



   $SIG{INT} =3D s=
ub {
Log("$$: INT"); };



 



   Log("$$: P=
rocessing
request");



 



   print
"\n\n";



 



   for(1 .. 10) p>

   {



     Log=
("$$:
Sleep $_ ");



     sle=
ep(1);



   }



 



   print
"Content\n";



 



   Log("$$:
Done");



 



 



I also have tried the following modification of the =
script
for mod_perl:



 



 



   #!/usr/bin/perl=



 



   use strict;



 



   use
Apache2::RequestRec;



   use
Apache2::Connection;



 



   Log("$$:
starting process");



 



   $SIG{PIPE} =3D =
sub {
Log("$$: PIPE!!"); };



   $SIG{TERM} =3D =
sub {
Log("$$: TERM!!");  };



   $SIG{HUP} =3D s=
ub {
Log("$$: HUP"); };



   $SIG{INT} =3D s=
ub { Log("$$:
INT"); };



 



   local our $Conn=
=3D
Apache2::RequestRec->connection();



 



   Log("$$:
Processing request");



 



   print
"\n\n";



 



   for(1 .. 10) p>

   {



     Log=
("$$:
Sleep $_, aborted:", $Conn->aborted());



     sle=
ep(1);



   }



 



   print
"Content\n";



 



   Log("$$:
Done");



 



 



and another modification for mod_fcgid (same idea wi=
th
trying to intercept signals and both with and w/o trying to use Apache2::Co=
nnection).



 



Log() function just outputs messages to a log file, =
that i
am tail -f 'ing.



 



 



I make a request using curl,



 



curl http://l=
ocalhost/script.pl



 



and also have tried LWP::UserAgent.



 



The way I test it is run the request process (either=
curl or
a simple .pl with a request made via LWP::UserAgent), and Control-C at some
point (while watching 'Sleep XX' messages appear in the log file). =



 



In all three cases with both LWP and curl i see the =
same
behavior - no indication of a client dropping the connection (even with
aborted() method of mod_perl) whatsoever, no signals, no messages about cli=
ent
dropping connection appearing in error.log of the server (LogLevel is set t=
o
'info'), etc. The CGI process in CGI case doesn't get terminate=
d and / or
killed; it continues to loop and sleep until 10 seconds pass.



 



 



From what I have been able to find, I tried:



 



* Looks like adding print STDOUT in the loop should =
cause
PIPE signal ('broken pipe'), I tried adding 'print STDOUT "=
; "' right
before sleep() call in the loop with no luck.



* Trying to see if the same print before sleep() wou=
ld
return failure ('print STDOUT " " or Log("Print failed!&=
quot;)',
w/o any luck



* In mod_perl tests, trying to use
Apache2::RequestRec->print() instead of print.



* LogLevel info should be giving me messages about c=
lients
dropping connections in error.log. I am not seeing any.



 



 



In addition, I clearly recall solving the same probl=
em under
mod_perl and Apache using $Conn->aborted() method, and it worked (but th=
at
was a different version of Apache 2 and mod_perl, unfortunately, I don=E2=
€™t have
that env right now to compareâ€=A6).



 



I have tried this on 2 versions of Apache and mod_pe=
rl,



 



* Ubuntu + apache 2.2.8 / mod_perl 2.0.3:



 



  root@vmubuntu ~/api
# apache2 -V



  Server version:
Apache/2.2.8 (Ubuntu)



  Server built: yle=3D"">   Feb  2
2008 04:03:01



  Server's Module
Magic Number: 20051115:11



  Server loaded: tyle=3D"">  APR 1.2.11, APR-Util 1.2.12



  Compiled using: APR
1.2.11, APR-Util 1.2.12



  Architecture: yle=3D"">   32-bit



  Server MPM: e=3D"">     Prefork



    threaded:=
     no



      an>forked:     yes (variable pr=
ocess count)



  Server compiled
with....



   -D
APACHE_MPM_DIR=3D"server/mpm/prefork"



   -D APR_HAS_SEND=
FILE



   -D APR_HAS_MMAP=



   -D APR_HAVE_IPV=
6
(IPv4-mapped addresses enabled)



   -D
APR_USE_SYSVSEM_SERIALIZE



   -D
APR_USE_PTHREAD_SERIALIZE



   -D
SINGLE_LISTEN_UNSERIALIZED_ACCEPT



   -D
APR_HAS_OTHER_CHILD



   -D
AP_HAVE_RELIABLE_PIPED_LOGS



   -D
DYNAMIC_MODULE_LIMIT=3D128



   -D
HTTPD_ROOT=3D""



   -D
SUEXEC_BIN=3D"/usr/lib/apache2/suexec"



   -D
DEFAULT_PIDLOG=3D"/var/run/apache2.pid"



   -D DEFAULT_SCOR=
EBOARD=3D"logs/apache_runtime_status"



   -D
DEFAULT_LOCKFILE=3D"/var/run/apache2/accept.lock"



   -D
DEFAULT_ERRORLOG=3D"logs/error_log"



   -D
AP_TYPES_CONFIG_FILE=3D"/etc/apache2/mime.types"



   -D
SERVER_CONFIG_FILE=3D"/etc/apache2/apache2.conf"



 



* Gentoo + apache 2.2.11 + mod_perl 2.0.4:



 



   newcore tmp #
apache2 -V



   Server version:
Apache/2.2.11 (Unix)



   Server built: pan style=3D"">   Oct 21 2009 16:42:25



   Server's Mo=
dule
Magic Number: 20051115:21



   Server loaded:<=
span style=3D"">  APR 1.2.8, APR-Util 1.2.8



   Compiled using:=
APR
1.2.8, APR-Util 1.2.8



   Architecture: pan style=3D"">   32-bit



   Server MPM: n style=3D"">     Prefork



     thr=
eaded:     no



     =C2=
=A0 forked:     yes (var=
iable process count)



   Server compiled
with....



    -D
APACHE_MPM_DIR=3D"server/mpm/prefork"



    -D
APR_HAS_SENDFILE



    -D APR_HA=
S_MMAP



    -D APR_HA=
VE_IPV6
(IPv4-mapped addresses enabled)



    -D
APR_USE_SYSVSEM_SERIALIZE



    -D
APR_USE_PTHREAD_SERIALIZE



    -D
SINGLE_LISTEN_UNSERIALIZED_ACCEPT



    -D
APR_HAS_OTHER_CHILD



    -D
AP_HAVE_RELIABLE_PIPED_LOGS



    -D
DYNAMIC_MODULE_LIMIT=3D128



  =C2=
 Â=A0-D HTTPD_ROOT=3D"/usr"



    -D
SUEXEC_BIN=3D"/usr/sbin/suexec"



    -D
DEFAULT_PIDLOG=3D"/var/run/httpd.pid"



    -D
DEFAULT_SCOREBOARD=3D"logs/apache_runtime_status"



    -D
DEFAULT_LOCKFILE=3D"/var/run/accept.lock"



    -D
DEFAULT_ERRORLOG=3D"logs/error_log"



    -D AP_TYP=
ES_CONFIG_FILE=3D"/etc/apache2/mime.types"



    -D
SERVER_CONFIG_FILE=3D"/etc/apache2/httpd.conf"



 



 



 



As you can see, both servers are running prefork mpm=
..







 Would anyone have a suggestion for this proble=
m? Ideally I would like either to be able to somehow detect client droppin=
g connection from his side from within the script, or Apache itself just ki=
lling the worker / CGI process whenever it detects that.


Fi.

ass=3D"MsoNormal">



 



 



 



 



 



 




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