I've seen quite often that Perl was reusing reference addresses after garbage collection had them released before.
I was curious as to how often this address reusing happens:
#!/bin/bash
for i in {1..15}; do
perl -Mstrict -wle'
use strict;
use warnings;
my %addr;
my $count = 0;
my $tries = 2**$ARGV[0];
for my $try (1..$tries) {
my %h;
for (reverse 1..1000) {
$h{$_} = { value => $_};
$count++;
}
$addr{$_}++ for values %h;
}
my $reused = scalar grep $addr{$_}>1, keys %addr;
my $addrs = scalar keys %addr;
print "Address of reference reused $reused times, all addresses $addrs
+, in $count tries";' $i
done
Address of reference reused 1 times, all addresses 1999, in 2000 tries
Address of reference reused 1001 times, all addresses 2999, in 4000 tr
+ies
Address of reference reused 2995 times, all addresses 3007, in 8000 tr
+ies
Address of reference reused 3011 times, all addresses 3023, in 16000 t
+ries
Address of reference reused 3043 times, all addresses 3055, in 32000 t
+ries
Address of reference reused 3107 times, all addresses 3119, in 64000 t
+ries
Address of reference reused 3235 times, all addresses 3247, in 128000
+tries
Address of reference reused 3491 times, all addresses 3503, in 256000
+tries
Address of reference reused 4003 times, all addresses 4015, in 512000
+tries
Address of reference reused 5027 times, all addresses 5039, in 1024000
+ tries
Address of reference reused 7075 times, all addresses 7087, in 2048000
+ tries
Address of reference reused 11171 times, all addresses 11183, in 40960
+00 tries
Address of reference reused 19363 times, all addresses 19375, in 81920
+00 tries
Address of reference reused 35747 times, all addresses 35759, in 16384
+000 tries
Address of reference reused 68515 times, all addresses 68527, in 32768
+000 tries
These numbers seem to be stable on my machine across multiple runs.
The bottom line is that address reusing happens all the time.
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.