Re: Passing an IO:Handle to a Thread

[Chris Hall]

On Fri, 29 Feb 2008 Dave Mitchell wrote

On Wed, Feb 27, 2008 at 08:15:36AM -0800, Dean Arnold wrote:

As to shared object destruction:

pre-5.10.0: once per thread, requires some extra bookkeeping to make sure
it "does the right thing"

5.10.0: once in the last referencing thread (fixed in CORE)

Huh?

   use warnings;
   use strict;

   use threads;
   use threads::shared;

   sub DESTROY { warn "DESTROY $_[0]\n" }

   my $h = bless {};
   share $h;
   threads->new(sub {})->join;

$ perl5100t /tmp/p
DESTROY main=HASH(0x98fb844)
DESTROY main=HASH(0x98748c4)
$

...but I have tried the following:

---Test-1---
I add a little to the above, ending up with:

    use warnings;
    use strict;

    use threads;
    use threads::shared;

    print "threads v$threads::VERSION",
          " & threads::shared v$threads::shared::VERSION\n" ;

    sub DESTROY { my $s = shift ; warn "DESTROY $s: ", %$s, "\n" }

    my $h = bless {Test => -1} ;            # )
    warn "Object \$h is $h: ", %$h, "\n" ;  # ) Object construction
    share $h;                               # )

    threads->new(sub {})->join;

which gives me:

  Perl v5.10.0 & threads v1.67 & threads::shared v1.14
  Object $h is main=HASH(0x22b08c): Test-1
  DESTROY main=HASH(0x18b305c):
  DESTROY main=HASH(0x22b08c):

and:

  Perl v5.8.8 & threads v1.69 & threads::shared v1.17
  Object $h is main=HASH(0x6054e0): Test-1
  DESTROY main=HASH(0x722ca0):
  DESTROY main=HASH(0x6054e0):

Noting the empty Hashes !



---Test-2---
Replacing the object construction bit by:

    my %b : shared = (Test => -1) ;
    my $h = bless \%b ;

gives:

  Perl v5.10.0 & threads v1.67 & threads::shared v1.14
  Address \%b is: HASH(0x1887814), Value: Test-2
  DESTROY main=HASH(0x1887814): Test-2

and:

  Perl v5.8.8 & threads v1.69 & threads::shared v1.17
  Address \%b is: HASH(0x6b0f80), Value: Test-2
  DESTROY main=HASH(0x6b0f80): Test-2

Which is the expected behaviour for V5.10.0, but not for v5.8.8 ?



---Test-3---
However:

    my $h = &share({Test => -3}) ;
    warn "Scalar \$h is $h:", %$h, "\n" ;
    bless $h ;

which you might think would work, doesn't:

  Perl v5.10.0 & threads v1.67 & threads::shared v1.14
  Scalar $h is HASH(0x22b08c):
  DESTROY main=HASH(0x18b52d4):
  DESTROY main=HASH(0x22b08c):

and similarly for v5.8.8.

---Test-4---
So... perhaps it's share that I don't understand, so I tried.

    my $h = &share({}) ;
    %$h = (Test => -4) ;
    bless $h ;
    warn "Object \$h is $h: ", %$h, "\n" ;

gives:

  Perl v5.10.0 & threads v1.67 & threads::shared v1.14
  Object $h is main=HASH(0x22b08c): Test-4
  DESTROY main=HASH(0x18b72e4): Test-4
  DESTROY main=HASH(0x22b08c): Test-4

and similarly for v5.8.8.

---Conclusion---

Well, I'm stumped.



Whatever my $h = &share({}) does, it's not the same as
         my %b : shared ; my $h = \%b ;





Chris
--
Chris Hall               highwayman.com            +44 7970 277 383

I had a feeling that there was some significance attached to the order of the blessing and sharing. Now I'm not so sure... So, whatever share $h does, it doesn't appear to be to cause the thing pointed to by $h to become shared -- or perhaps it does, but empties it. Note that the shared hash is blessed: suggesting the order is significant. Whatever share $h does, it doesn't appear useful when $h is a ref to something. Whatever &share({a => 1}) does, it doesn't return a ref to an anonymous hash containing a => 1 !! I don't see any difference between v5.10.0 and 5.8.8... could be that I'm using late model threads & threads::shared with v5.8.8 ?

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