=head1 INHERITANCE
Benchmark inherits from no other class, except of course
-for Exporter.
+from Exporter.
=head1 CAVEATS
clearcache clearallcache disablecache enablecache);
%EXPORT_TAGS=( all => [ @EXPORT, @EXPORT_OK ] ) ;
-$VERSION = 1.18;
+$VERSION = 1.20;
# --- ':hireswallclock' special handling
# getting a too low initial $n in the initial, 'find the minimum' loop
# in &countit. This, in turn, can reduce the number of calls to
# &runloop a lot, and thus reduce additive errors.
+ #
+ # Note that its possible for the act of reading the system clock to
+ # burn lots of system CPU while we burn very little user clock in the
+ # busy loop, which can cause the loop to run for a very long wall time.
+ # So gradually ramp up the duration of the loop. See RT #122003
+ #
my $tbase = Benchmark->new(0)->[1];
- while ( ( $t0 = Benchmark->new(0) )->[1] == $tbase ) {} ;
+ my $limit = 1;
+ while ( ( $t0 = Benchmark->new(0) )->[1] == $tbase ) {
+ for (my $i=0; $i < $limit; $i++) { my $x = $i / 1.5 } # burn user CPU
+ $limit *= 1.1;
+ }
$subref->();
$t1 = Benchmark->new($n);
$td = &timediff($t1, $t0);