in reply to Re^6: Is this absurd, or have I not RTFM?
in thread Is this absurd, or have I not RTFM?

Please try this 

#!/usr/bin/perl --
package MyModule;
use Devel::Peek;

sub new {
    my $obj = bless { '$$' => $$ }, shift;
    print "## $$ IN NEW $obj ##\n";
    return $obj;
}

sub DESTROY {
    print "#### BEGIN DESTROY: $$ : @_ ####\n";
    print Dump( @_ );
    print "###### END DESTROY: $$ : @_ ######\n";
}

1;

package MyServer;
use parent qw[ Net::Server::PreFork ];
our $hardtodestroy = MyModule->new;

sub child_finish_hook {
    undef $hardtodestroy;
}
1;

package main;
STDOUT->autoflush(1);
print "## this is perl $]\n";
MyServer->run(
    max_servers       => 1,
    min_servers       => 1,
    min_spare_servers => 0,
    max_spare_servers => 0
);

[download]

Replies are listed 'Best First'.
Re^8: Is this absurd, or have I not RTFM?
by petermogensen (Sexton) on May 19, 2014 at 10:03 UTC 
    2014/05/19-11:57:52 Server closing!
#### BEGIN DESTROY: 13138 : MyModule=HASH(0x1441b78) ####
SV = IV(0x190cba0) at 0x190cbb0
  REFCNT = 1
  FLAGS = (ROK,READONLY)
#### BEGIN DESTROY: 13138 : MyModule=HASH(0x1441b78) ####
SV = IV(0x190c810) at 0x190c820
  REFCNT = 1
  FLAGS = (ROK,READONLY)
  RV = 0x1441b78
  SV = PVHV(0x1448880) at 0x1441b78
    REFCNT = 1
    FLAGS = (OBJECT,SHAREKEYS)
    STASH = 0x1460d40   "MyModule"
    ARRAY = 0x1459360  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "$$" HASH = 0x7f8f5659
    SV = IV(0x1460268) at 0x1460278
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 13137
###### END DESTROY: 13138 : MyModule=HASH(0x1441b78) ######
#### BEGIN DESTROY: 13137 : MyModule=HASH(0x1441b78) ####
SV = IV(0x150bd48) at 0x150bd58
  REFCNT = 1
  FLAGS = (ROK,READONLY)
  RV = 0x1441b78
  SV = PVHV(0x1448880) at 0x1441b78
    REFCNT = 1
    FLAGS = (OBJECT,SHAREKEYS)
    STASH = 0x1460d40   "MyModule"
    ARRAY = 0x1459360  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "$$" HASH = 0x7f8f5659
    SV = IV(0x1460268) at 0x1460278
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 13137
###### END DESTROY: 13137 : MyModule=HASH(0x1441b78) ######

    [download]

    So ... as it shows process 13138 is calling DESTROY twice for the same object. Apparently it gets interrupted by shutdown half way through the first invocation (but gets far enough to crash in other ways **). What I'm wondering about is what makes Perl retry the DESTROY method for the object at a later time.

    **: This means, that if the objects DESTROY method is an XS function you can manage to call free() on a C pointer during the first invocation before you get interrupted. ... and then calling free() again in the second invocation will cause glibc to complain loudly.

[reply]
[d/l]
      On current perl versions XS functions are not interrupted unless you activate the "unsafe" signals in some way (see perlipc).
[reply]

      Um, so where is the part about the perl version?

[reply]
        Oh... sorry... I didn't notice you had included that, ... since I actually already mentioned it. Perl 5.14.2 on Ubuntu: 
        ## 13137 IN NEW MyModule=HASH(0x1441b78) ##
## this is perl 5.014002

        [download]
[reply]
[d/l]
      Might also need to add 
       
sub post_child_cleanup_hook {
    undef $hardtodestroy;
}

      [download]
[reply]
[d/l]
        Still 3 DESTROY calls,... 2 from the same process. Only make the output less readable. 
        ^C#### BEGIN DESTROY: 13406 : MyModule=HASH(0x15bfb78) ####
SV = IV(0x1a8acb0) at 0x1a8acc0
  REFCNT = 1
  FLAGS = (ROK,READONLY)
  RV = 0x15bfb78
  SV = PVHV(0x15c6880) at 0x15bfb78
    REFCNT = 1
    FLAGS = (OBJECT,SHAREKEYS)
    STASH = 0x15ded40   "MyModule"
    ARRAY = 0x15d7360  (0:7, 1:1)
2014/05/19-12:22:44 Server closing!
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "$$" HASH = 0x7f8f5659
    SV = IV(0x15de268) at 0x15de278
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 13405
#### BEGIN DESTROY: 13405 : MyModule=HASH(0x15bfb78) ####
SV = IV(0x1a8ac80) at 0x1a8ac90
  REFCNT = 1
  FLAGS = (ROK,READONLY)
  RV = 0x15bfb78
  SV = PVHV(0x15c6880) at 0x15bfb78
    REFCNT = 1
    FLAGS = (OBJECT,SHAREKEYS)
    STASH = 0x15ded40   "MyModule"
    ARRAY = 0x15d7360  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "$$" #### BEGIN DESTROY: 13406 : MyModule=HASH(0x15bfb78) ####
HASH = 0x7f8f5659
    SV = SV = IV(0x15de268) at 0x15de278
      REFCNT = 1
      FLAGS = (IOK,pIOK)
IV(0x1a8a920) at 0x1a8a930
  REFCNT = 1
  FLAGS = (ROK,READONLY)
      IV = 13405  RV = 0x15bfb78

  ###### END DESTROY: 13405 : MyModule=HASH(0x15bfb78) ######
SV = PVHV(0x15c6880) at 0x15bfb78
    REFCNT = 1
    FLAGS = (OBJECT,OOK,SHAREKEYS)
    STASH = 0x15ded40   "MyModule"
    ARRAY = 0x1a91980  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "$$" HASH = 0x7f8f5659
    SV = IV(0x15de268) at 0x15de278
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 13405
###### END DESTROY: 13406 : MyModule=HASH(0x15bfb78) ######

        [download]
[reply]
[d/l]

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