http://qs321.pair.com?node_id=679209


in reply to DBI, fork, and clone.

Thanks for this. I'm doing basically the same, but it's reassuring to see other's solutions. The error message can be avoided by passing an empty hash ref to the clone method like so: $dbh->clone({}); I guess they have forgotten to do an my $args = shift || {} or somesuch, but I'm too busy to check now :-) Regards -- t

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Re^2: DBI, fork, and clone.
by Anonymous Monk on Jan 08, 2009 at 08:16 UTC
    I have been using the above code successfully since 2007 when it was first posted, but recently I upgraded my Perl to 5.8.8, DBI 1.604, and DBD::Pg 2.10.7.

    I'm having the same issue as before where the main process will go haywire and report random query errors. Did something change recently or is there a new workaround?

[reply]
      Here is the code I was using that is now broken. I have defined $dbh as a global variable using 'our' pragma. 
       if (my $pid = fork) {
      l("D","$restr [$tbn] [se_id:$se->{scenario_exec_id}] forking ($p
+id) $se->{suite_name}:$se->{scenario_name}");
      $V{scenario_exec_childs}->{$se->{scenario_exec_id}}{pid} = $pid;
      $V{scenario_exec_childs}->{$se->{scenario_exec_id}}{start_time} 
+= $before_exec;
      # prepopulate before next cycle for state consistency, $se is re
+ferenced in the $ses array ref in main loop
      $se->{status} = "RUNNING";
      set_scenario_exec_state($se,{ -testbed_id=>$tb_id, -pid=>$pid, -
+start=>"now()", status=>"RUNNING" });
      sleep 2;
    } elsif (defined $pid) {
      $0 = "$restr $tbn SE:$se->{scenario_exec_id}";
      l("D", "top of se fork: " . $dbh);

      # once and for all, I think I have figured out the forking + DBI
+ connection handling issue! 2007-04-23, 
      # we clone the handle, undef it, then copy over the old variable
+ in the new process

      # suppress warning from clone call... I think something is broke
+n with DBI 
      # produces: Can't set DBI::db=HASH(0x82cf704)->{User}: unrecogni
+sed attribute or invalid value at 
      # /volume/perl/lib/site_perl/5.8.5/i386-freebsd/DBI.pm line 648.
      my $saved_warn_handler = $SIG{__WARN__}; $SIG{__WARN__} = sub {}
+;
      my $child_dbh = $dbh->clone(); $SIG{__WARN__} = $saved_warn_hand
+ler;
      l("D", "cloned child_dbh: " . $child_dbh);
      $dbh->{InactiveDestroy} = 1; undef $dbh; $dbh = $child_dbh;

      [download]

      20090108 Janitored by Corion: Changed PRE tags to CODE tags, as per Writeup Formatting Tips

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