Hi Stefan, thanks for your reporting, I'm going to have a look in lab for
applying the patch in next release.
Thanks again and regards
2014-03-18 14:48 GMT+01:00 Stefan <[email protected]>:
> Hi Emilio,
>
> thanks for having a look at this.
>
> I did some more tests and research in the meantime.
>
> I was able to reproduce using a simple shell script as the check
> command, which does not do anything but sleep a period of time higher
> than the timeout.
>
> I then tried to understand how farmguardian works. It is using
> $SIG{ALRM} for timeout handling when executing the check command.
> http://perldoc.perl.org/perlipc.html#Signals says "If the operation
> being timed out is system() or qx(), this technique is liable to
> generate zombies". I also read many postings in various forums from
> persons having problems with zombies using perl. I am not an expert
> but as I would understand it now, if the child process (check command)
> times out and the parent (farmguardian) continues, the child becomes a
> zombie if the parent does not read its status. So as a quick fix I
> modified the farmguardian script to use a non-blocking waitpid when
> the check command times out to read the child status. For whatever
> reason this leaves me with still one zombie per farm that has failing
> farmguardian checks, but more important they do not keep adding up
> anymore.
>
> This is how I modified farmguardian:
>
> use Proc::Daemon;
>
> changed to
>
> use Proc::Daemon;
> use POSIX(WNOHANG);
>
> and
>
> if ($@){
> warn "$command timed out.\n";
> $timedout = 1;
> }
>
> changed to
>
> if ($@){
> warn "$command timed out.\n";
> $timedout = 1;
> do {
> my $kid = waitpid(-1, WNOHANG);
> #print "pid $kid exited\n";
> }
> while $kid > 0;
> }
>
>
> I don't know if this would work for others but it seems to work for me
> right now and I hope it helps your lab study. I will post an update if
> anything worth mentioning changes.
>
> Kind Regards,
> Stefan
>
>
> On Thu, Feb 13, 2014 at 5:07 PM, Emilio Campos
> <[email protected]> wrote:
> > Hi Stefan, we have to configure a lab to study this behaviour, your
> reported
> > information will help us.
> >
> > Thanks.
> >
> >
> > 2014-02-13 15:37 GMT+01:00 Stefan <[email protected]>:
> >>
> >> Please find a farmguardian log excerpt and additional info below.
> >>
> >> I have noticed that stopping the target service (e.g. Apache) does not
> >> seem to result in defunct processes. But they certainly appear when I
> >> disconnect the real server's virtual NIC for example.
> >>
> >> Kind Regards,
> >> Stefan
> >>
> >> Farmguardian Config:
> >> t-c-443: check_tcp -H HOST -p PORT -S -w 5 -c 5 -t 10
> >> t-n-80: check_http -I HOST -p PORT -H 't-n.somedomain' -u '/abc/app'
> >> -w 5 -c 5 -t 10 -e '302 Found'
> >> t-n-443: check_http -I HOST -p PORT -S -H 't-n.somedomain' -u
> >> '/abc/app' -w 5 -c 5 -t 10 -e '200 OK'
> >> t-o-80: check_http -I HOST -p PORT -H 't-o.somedomain' -w 5 -c 5 -t
> >> 10 -e '302 Found'
> >> t-o-443: check_http -I HOST -p PORT -S -H 't-o.somedomain' -w 5 -c 5
> >> -t 10 -e '302 Found'
> >>
> >> Process list:
> >> ...
> >> 1 1342 1342 1342 ? -1 Ss 0 0:00
> >> /usr/local/zenloadbalancer/app/mini_httpd/mini_httpd -C
> >> /usr/local/zenloadbalancer/app/mini_httpd/mini_httpd.conf
> >> 1 27924 27924 27924 tty1 7057 Ss 0 0:00 /bin/login --
> >> 27924 21781 21781 27924 tty1 7057 S 0 0:00 \_ -bash
> >> 21781 7057 7057 27924 tty1 7057 R+ 0 0:00 \_ ps axjf
> >> 1 28308 28085 28085 ? -1 S 0 0:05 /usr/bin/perl
> >> /usr/local/zenloadbalancer/app/farmguardian/bin/farmguardian t-c-443
> >> -l
> >> 1 28342 28085 28085 ? -1 S 0 0:04 /usr/bin/perl
> >> /usr/local/zenloadbalancer/app/farmguardian/bin/farmguardian t-o-80 -l
> >> 28342 6507 28085 28085 ? -1 Z 0 0:00 \_ [sh]
> >> <defunct>
> >> 1 28377 28085 28085 ? -1 S 0 0:04 /usr/bin/perl
> >> /usr/local/zenloadbalancer/app/farmguardian/bin/farmguardian t-n-443
> >> -l
> >> 28377 6512 28085 28085 ? -1 Z 0 0:00 \_ [sh]
> >> <defunct>
> >> 1 28412 28085 28085 ? -1 S 0 0:04 /usr/bin/perl
> >> /usr/local/zenloadbalancer/app/farmguardian/bin/farmguardian t-n-80 -l
> >> 28412 6506 28085 28085 ? -1 Z 0 0:00 \_ [sh]
> >> <defunct>
> >> 1 28450 28085 28085 ? -1 S 0 0:04 /usr/bin/perl
> >> /usr/local/zenloadbalancer/app/farmguardian/bin/farmguardian t-o-443
> >> -l
> >> 28450 6500 28085 28085 ? -1 Z 0 0:00 \_ [sh]
> >> <defunct>
> >>
> >> Farmguardian log excerpt t-o-80:
> >> The servers timeout is: 10
> >> checking:
> >> farmname: t-o-80
> >> timeout: 10
> >> blacklist:
> >> timetocheck: 10
> >> portadmin: -1
> >> server[0]: a.b.234.20:80
> >> server[1]: a.b.235.20:80
> >> check: check_http -I HOST -p PORT -H 't-o.somedomain' -w 5 -c
> >> 5 -t 10 -e '302 Found'
> >>
> >> execution in Tue Feb 4 10:21:34 2014 ::
> >> server[0]: a.b.234.20:80
> >> Backend status 0: up
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.234.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> timedout: 0
> >> errorcode: 0
> >> No state changed for the backend.
> >> server[1]: a.b.235.20:80
> >> Backend status 1: up
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.235.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> timedout: 0
> >> errorcode: 0
> >> No state changed for the backend.
> >> The servers timeout is: 10
> >> checking:
> >> farmname: t-o-80
> >> timeout: 10
> >> blacklist:
> >> timetocheck: 10
> >> portadmin: -1
> >> server[0]: a.b.234.20:80
> >> server[1]: a.b.235.20:80
> >> check: check_http -I HOST -p PORT -H 't-o.somedomain' -w 5 -c
> >> 5 -t 10 -e '302 Found'
> >>
> >> execution in Tue Feb 4 10:21:44 2014 ::
> >> server[0]: a.b.234.20:80
> >> Backend status 0: up
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.234.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> timedout: 0
> >> errorcode: 0
> >> No state changed for the backend.
> >> server[1]: a.b.235.20:80
> >> Backend status 1: up
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.235.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> /usr/local/zenloadbalancer/app/libexec/check_http -I a.b.235.20 -p 80
> >> -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found' timed out.
> >> timedout: 1
> >> errorcode: 0
> >> **execution error in '
> >> /usr/local/zenloadbalancer/app/libexec/check_http -I a.b.235.20 -p 80
> >> -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found' ', output::**
> >> The servers timeout is: 10
> >> checking:
> >> farmname: t-o-80
> >> timeout: 10
> >> blacklist:
> >> timetocheck: 10
> >> portadmin: -1
> >> server[0]: a.b.234.20:80
> >> server[1]: a.b.235.20:80
> >> check: check_http -I HOST -p PORT -H 't-o.somedomain' -w 5 -c
> >> 5 -t 10 -e '302 Found'
> >>
> >> execution in Tue Feb 4 10:22:04 2014 ::
> >> server[0]: a.b.234.20:80
> >> Backend status 0: up
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.234.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> timedout: 0
> >> errorcode: 0
> >> No state changed for the backend.
> >> server[1]: a.b.235.20:80
> >> Backend status 1: fgDOWN
> >> command: /usr/local/zenloadbalancer/app/libexec/check_http -I
> >> a.b.235.20 -p 80 -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found'
> >> /usr/local/zenloadbalancer/app/libexec/check_http -I a.b.235.20 -p 80
> >> -H 't-o.somedomain' -w 5 -c 5 -t 10 -e '302 Found' timed out.
> >> timedout: 1
> >> errorcode: 0
> >> No state changed for the backend.
> >>
> >>
> >>
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