From: George Wang <gwang@...>
Date: 2007-03-10T05:37:45+09:00
Subject: Re: Strange interference between LSAPI, popen3 and MySQL


OK, we figured out what is wrong. "reopen" method need to be defined for 
"LSAPI" class since popen3 calls "reopen". LSAPI new release will 
address this.

However, the root cause of broken MySQL connection is not LSAPI's fault, 
actually a bug in ruby's "open3.rb", the fix is like:

def popen3(*cmd)
    pw = IO::pipe   # pipe[0] for read, pipe[1] for write
    pr = IO::pipe
    pe = IO::pipe

    pid = fork{
      # child
      fork{
  # grandchild
+     begin

  pw[1].close
  STDIN.reopen(pw[0])
  pw[0].close

  pr[0].close
  STDOUT.reopen(pr[1])
  pr[1].close

  pe[0].close
  STDERR.reopen(pe[1])
  pe[1].close

        exec(*cmd)
+     ensure
+  exit!(0)
+     end
      }
      exit!(0)
    }

    pw[0].close
    pr[1].close
    pe[1].close
    Process.waitpid(pid)
    pi = [pw[1], pr[0], pe[0]]
    pw[1].sync = true
    if defined? yield
      begin
  return yield(*pi)
      ensure
  pi.each{|p| p.close unless p.closed?}
      end
    end
    pi
  end
  module_function :popen3
end

Whenever an error raise in the grandchild process, this process will not 
be terminated properly, and DB connection was closed in this process, 
thus the DB connection error in the main process. It happens to both 
mongrel and LSAPI.

With above fix, DB connection is in good shape even without the LSAPI 
fix, just the command was not  getting executed.

Best Regards,
George Wang
http://www.litespeedtech.com/



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