Backgroundrb devel - Aug 2006 - strange problem with system call

Hi,

I am using backgroundrb to create a automated system of typo blogs.So, users
can create new typo applications using web interface and all that jazz.

Now..its working perfectly except one minor glitch. Since latest version of
typo has a command called "typo", i simply use that command to install
new
typo app.And it works.

def do_work(args)
    DIR = "/home/foobar/public_html"
    username = args
    blog_name = username + "_blog"
    # creation part works flawlessly so lets skip that.
    # there is a problem while stopping it.
    if (Dir.chdir(DIR)) == 0
          current_dir = `pwd`
          @logger.debug("Current directory is #{current_dir}")
          stop_command = "typo stop "+ blog_name
          debug_stuff `#{stop_command}`
#line no 33
          @logger.debug("### #{debug_stuff}")
    else
      @logger.debug("### Error changing directory")
    end
end

Now let me assure that, args has correct username, because starting of
blog,migrating from sqlite to mysql works perfectly using this worker
thread.The only glitch is, in line # 33, "typo stop " doesn''t
work.I have
tried system also.system returns true, so typo should be stopped.But when i
do "ps aux|grep foobar" , it isn''t ,process is still there.

When i tried `command`. All i got in debug_stuff variable is a empty
string.However, when i try same stuff from irb, it works as expected and
typo stopped.Now..again let me assure that, the worker thread IS getting
CALLED.

I have tried various stuff.But since, I am simply not able to debug, where
the heck problem is, I am lost. I was told that, system or `command` both
wait for the command to finish execution to resume normal execution.But for
me it SEEMS that the call to "typo stop #{blog_name}" returns
immediately.
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Many times those calls to start/stop scripts get backgrounded, so it
could actually be returning instantly.  You could try wrapping it, or
go check what typo stop is actually doing and make sure there''s no
"blah blah &" in the script.

You could also try using popen and popen3 processes instead of the
`command` backticks.  I find those hard to debug as you don''t know
what''s going on when they run.

This will allow you to see stdin, stderr, and stdout on the process.  Sample:

cmd_to_run = "typo stop"

       stdin, stdout, stderr = Open3.popen3(cmd_to_run)

       s_stderr = stderr.read.to_s
       s_stdout = stdout.read.to_s

       # if you''d like to see it
       logger.info "stdout: #{s_stdout}"
       logger.info "stderr: #{s_stderr}"

       if s_stderr.empty? && s_stdout.starts_with?("error stuff
here")
         return true
       else
         errors.add_to_base("error msg here")
         return false
       end

hope that helps!

On 8/21/06, hemant <gethemant at gmail.com> wrote:
> Hi,
>
> I am using backgroundrb to create a automated system of typo blogs.So,
users
> can create new typo applications using web interface and all that jazz.
>
> Now..its working perfectly except one minor glitch. Since latest version of
> typo has a command called "typo", i simply use that command to
install new
> typo app.And it works.
>
> def do_work(args)
>     DIR = "/home/foobar/public_html"
>     username = args
>     blog_name = username + "_blog"
>      # creation part works flawlessly so lets skip that.
>     # there is a problem while stopping it.
>     if (Dir.chdir(DIR)) == 0
>           current_dir = `pwd`
>           @logger.debug("Current directory is #{current_dir}")
>           stop_command = "typo stop "+ blog_name
>           debug_stuff = `#{stop_command}`
>                                               #line no 33
>           @logger.debug("### #{debug_stuff}")
>     else
>       @logger.debug("### Error changing directory")
>     end
> end
> Now let me assure that, args has correct username, because starting of
> blog,migrating from sqlite to mysql works perfectly using this worker
> thread.The only glitch is, in line # 33, "typo stop "
doesn''t work.I have
> tried system also.system returns true, so typo should be stopped.But when i
> do "ps aux|grep foobar" , it isn''t ,process is still
there.
>
> When i tried `command`. All i got in debug_stuff variable is a empty
> string.However, when i try same stuff from irb, it works as expected and
> typo stopped.Now..again let me assure that, the worker thread IS getting
> CALLED.
>
> I have tried various stuff.But since, I am simply not able to debug, where
> the heck problem is, I am lost. I was told that, system or `command` both
> wait for the command to finish execution to resume normal execution.But for
> me it SEEMS that the call to "typo stop #{blog_name}" returns
immediately.
>
>
>
>
> _______________________________________________
> Backgroundrb-devel mailing list
> Backgroundrb-devel at rubyforge.org
> http://rubyforge.org/mailman/listinfo/backgroundrb-devel
>
>

-- 
Charles Brian Quinn
self-promotion: www.seebq.com
highgroove studios: www.highgroove.com
slingshot hosting: www.slingshothosting.com

Yeah Charles has the right idea. One other way to do what you want  
would be to kill the process directly by running

pid = `ps axww | grep -v grep | grep typo`  # or whatever the process  
is called?

then get the pid out of that text and do a kill -9 on it. But I think  
you are probably better off with a popen solution. I am going to be  
redoing the start scripts to use the daemons gem which might fix this  
problem.

-Ezra

On Aug 21, 2006, at 8:29 AM, Charles Brian Quinn wrote:
> Many times those calls to start/stop scripts get backgrounded, so it
> could actually be returning instantly.  You could try wrapping it, or
> go check what typo stop is actually doing and make sure there''s no
> "blah blah &" in the script.
>
> You could also try using popen and popen3 processes instead of the
> `command` backticks.  I find those hard to debug as you don''t know
> what''s going on when they run.
>
> This will allow you to see stdin, stderr, and stdout on the  
> process.  Sample:
>
> cmd_to_run = "typo stop"
>
>        stdin, stdout, stderr = Open3.popen3(cmd_to_run)
>
>        s_stderr = stderr.read.to_s
>        s_stdout = stdout.read.to_s
>
>        # if you''d like to see it
>        logger.info "stdout: #{s_stdout}"
>        logger.info "stderr: #{s_stderr}"
>
>        if s_stderr.empty? && s_stdout.starts_with?("error
stuff here")
>          return true
>        else
>          errors.add_to_base("error msg here")
>          return false
>        end
>
> hope that helps!
>
> On 8/21/06, hemant <gethemant at gmail.com> wrote:
>> Hi,
>>
>> I am using backgroundrb to create a automated system of typo  
>> blogs.So, users
>> can create new typo applications using web interface and all that  
>> jazz.
>>
>> Now..its working perfectly except one minor glitch. Since latest  
>> version of
>> typo has a command called "typo", i simply use that command
to
>> install new
>> typo app.And it works.
>>
>> def do_work(args)
>>     DIR = "/home/foobar/public_html"
>>     username = args
>>     blog_name = username + "_blog"
>>      # creation part works flawlessly so lets skip that.
>>     # there is a problem while stopping it.
>>     if (Dir.chdir(DIR)) == 0
>>           current_dir = `pwd`
>>           @logger.debug("Current directory is
#{current_dir}")
>>           stop_command = "typo stop "+ blog_name
>>           debug_stuff = `#{stop_command}`
>>                                               #line no 33
>>           @logger.debug("### #{debug_stuff}")
>>     else
>>       @logger.debug("### Error changing directory")
>>     end
>> end
>> Now let me assure that, args has correct username, because  
>> starting of
>> blog,migrating from sqlite to mysql works perfectly using this worker
>> thread.The only glitch is, in line # 33, "typo stop "
doesn''t
>> work.I have
>> tried system also.system returns true, so typo should be  
>> stopped.But when i
>> do "ps aux|grep foobar" , it isn''t ,process is still
there.
>>
>> When i tried `command`. All i got in debug_stuff variable is a empty
>> string.However, when i try same stuff from irb, it works as  
>> expected and
>> typo stopped.Now..again let me assure that, the worker thread IS  
>> getting
>> CALLED.
>>
>> I have tried various stuff.But since, I am simply not able to  
>> debug, where
>> the heck problem is, I am lost. I was told that, system or  
>> `command` both
>> wait for the command to finish execution to resume normal  
>> execution.But for
>> me it SEEMS that the call to "typo stop #{blog_name}" returns
>> immediately.
>>
>>
>>
>>
>> _______________________________________________
>> Backgroundrb-devel mailing list
>> Backgroundrb-devel at rubyforge.org
>> http://rubyforge.org/mailman/listinfo/backgroundrb-devel
>>
>>
>
>
> -- 
> Charles Brian Quinn
> self-promotion: www.seebq.com
> highgroove studios: www.highgroove.com
> slingshot hosting: www.slingshothosting.com
> _______________________________________________
> Backgroundrb-devel mailing list
> Backgroundrb-devel at rubyforge.org
> http://rubyforge.org/mailman/listinfo/backgroundrb-devel

Thanks guys,

I dont have any "&" in my code.But yes, popen solution sounds
better.
I will give it a spin.



On 8/21/06, Ezra Zygmuntowicz <ezmobius at gmail.com>
wrote:
>
>
>         Yeah Charles has the right idea. One other way to do what you want
> would be to kill the process directly by running
>
> pid = `ps axww | grep -v grep | grep typo`  # or whatever the process
> is called?
>
> then get the pid out of that text and do a kill -9 on it. But I think
> you are probably better off with a popen solution. I am going to be
> redoing the start scripts to use the daemons gem which might fix this
> problem.
>
> -Ezra
>
> On Aug 21, 2006, at 8:29 AM, Charles Brian Quinn wrote:
>
> > Many times those calls to start/stop scripts get backgrounded, so it
> > could actually be returning instantly.  You could try wrapping it, or
> > go check what typo stop is actually doing and make sure
there''s no
> > "blah blah &" in the script.
> >
> > You could also try using popen and popen3 processes instead of the
> > `command` backticks.  I find those hard to debug as you don''t
know
> > what''s going on when they run.
> >
> > This will allow you to see stdin, stderr, and stdout on the
> > process.  Sample:
> >
> > cmd_to_run = "typo stop"
> >
> >        stdin, stdout, stderr = Open3.popen3(cmd_to_run)
> >
> >        s_stderr = stderr.read.to_s
> >        s_stdout = stdout.read.to_s
> >
> >        # if you''d like to see it
> >        logger.info "stdout: #{s_stdout}"
> >        logger.info "stderr: #{s_stderr}"
> >
> >        if s_stderr.empty? && s_stdout.starts_with?("error
stuff here")
> >          return true
> >        else
> >          errors.add_to_base("error msg here")
> >          return false
> >        end
> >
> > hope that helps!
> >
> > On 8/21/06, hemant <gethemant at gmail.com> wrote:
> >> Hi,
> >>
> >> I am using backgroundrb to create a automated system of typo
> >> blogs.So, users
> >> can create new typo applications using web interface and all that
> >> jazz.
> >>
> >> Now..its working perfectly except one minor glitch. Since latest
> >> version of
> >> typo has a command called "typo", i simply use that
command to
> >> install new
> >> typo app.And it works.
> >>
> >> def do_work(args)
> >>     DIR = "/home/foobar/public_html"
> >>     username = args
> >>     blog_name = username + "_blog"
> >>      # creation part works flawlessly so lets skip that.
> >>     # there is a problem while stopping it.
> >>     if (Dir.chdir(DIR)) == 0
> >>           current_dir = `pwd`
> >>           @logger.debug("Current directory is
#{current_dir}")
> >>           stop_command = "typo stop "+ blog_name
> >>           debug_stuff = `#{stop_command}`
> >>                                               #line no 33
> >>           @logger.debug("### #{debug_stuff}")
> >>     else
> >>       @logger.debug("### Error changing directory")
> >>     end
> >> end
> >> Now let me assure that, args has correct username, because
> >> starting of
> >> blog,migrating from sqlite to mysql works perfectly using this
worker
> >> thread.The only glitch is, in line # 33, "typo stop "
doesn''t
> >> work.I have
> >> tried system also.system returns true, so typo should be
> >> stopped.But when i
> >> do "ps aux|grep foobar" , it isn''t ,process is
still there.
> >>
> >> When i tried `command`. All i got in debug_stuff variable is a
empty
> >> string.However, when i try same stuff from irb, it works as
> >> expected and
> >> typo stopped.Now..again let me assure that, the worker thread IS
> >> getting
> >> CALLED.
> >>
> >> I have tried various stuff.But since, I am simply not able to
> >> debug, where
> >> the heck problem is, I am lost. I was told that, system or
> >> `command` both
> >> wait for the command to finish execution to resume normal
> >> execution.But for
> >> me it SEEMS that the call to "typo stop #{blog_name}"
returns
> >> immediately.
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> Backgroundrb-devel mailing list
> >> Backgroundrb-devel at rubyforge.org
> >> http://rubyforge.org/mailman/listinfo/backgroundrb-devel
> >>
> >>
> >
> >
> > --
> > Charles Brian Quinn
> > self-promotion: www.seebq.com
> > highgroove studios: www.highgroove.com
> > slingshot hosting: www.slingshothosting.com
> > _______________________________________________
> > Backgroundrb-devel mailing list
> > Backgroundrb-devel at rubyforge.org
> > http://rubyforge.org/mailman/listinfo/backgroundrb-devel
>
>

-- 
nothing much to talk
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