Re^4: "require Carp" may be hazardous to your code (assume)

Note that I kick quite a kick out of the last half of that statement. I'm sure the very first thing that require does is exactly that anyway, so I'd never add such trivial code in an obvious attempt at micro-optimization.

Did you read the comment next to "require Carp::Heavy unless $INC{"Carp/Heavy.pm"};" in the source? It's not an optimization. It's done that way so the module runs when Safe disallows require.

Update:

I don't recall you having posted data to support your claim either.

( ~~On average, it takes me 4.24 ns to load Carp.~~ Oops, Time::HiRes loads Carp. New benchmarks in progress. )

>perl -MTime::HiRes=time -le "$t1=time; require Carp; $t2=time; print 
+$t2-$t1"
4.05311584472656e-006

>perl -MTime::HiRes=time -le "$t1=time; require Carp; $t2=time; print 
+$t2-$t1"
4.05311584472656e-006

>perl -MTime::HiRes=time -le "$t1=time; require Carp; $t2=time; print 
+$t2-$t1"
4.05311584472656e-006

>perl -MTime::HiRes=time -le "$t1=time; require Carp; $t2=time; print 
+$t2-$t1"
5.00679016113281e-006

>perl -MTime::HiRes=time -le "$t1=time; require Carp; $t2=time; print 
+$t2-$t1"
4.05311584472656e-006
[download]

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Re^5: "require Carp" may be hazardous to your code (assume) by tye (Sage) on Dec 05, 2006 at 20:02 UTC
Congratulations on your broken benchmark: `> perl -MTime::HiRes -le"print $INC{'Carp.pm'}" .../Carp.pm` [download] Note that you also didn't address that this practice predates the factorying out of the "heavy" parts. - tye	[reply] [d/l]
Re^6: "require Carp" may be hazardous to your code (assume) by ikegami (Patriarch) on Dec 05, 2006 at 21:17 UTC
Nice catch. I thought it was a bit fast... Without heavy bits: 1.34 ms `>perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; requi +re Carp; } $t2=time; print(($t2-$t1)/$ARGV[0])" 100000 0.00134 >perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; requi +re Carp; } $t2=time; print(($t2-$t1)/$ARGV[0])" 100000 0.00134 >perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; requi +re Carp; } $t2=time; print(($t2-$t1)/$ARGV[0])" 100000 0.00134` [download] With heavy bits: 4.75 ms `>perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; delet +e $INC{'Carp/Heavy.pm'}; require Carp; require Carp::Heavy; } $t2=tim +e; print(($t2-$t1)/$ARGV[0])" 100000 0.00475 >perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; delet +e $INC{'Carp/Heavy.pm'}; require Carp; require Carp::Heavy; } $t2=tim +e; print(($t2-$t1)/$ARGV[0])" 100000 0.00474` [download]	[reply] [d/l] [select]
Re^5: "require Carp" may be hazardous to your code (assume) by grinder (Bishop) on Dec 05, 2006 at 20:48 UTC
Using much more lightweight code (for a FreeBSD system), I get around 30 milliseconds when not loading Carp, and 90 msecs when I do. Here is the code I used: `use Carp; # comment this line out, or not use BSD::Process; my $t = BSD::Process->new->elapsed_time; print $t, $/; # time in milliseconds` [download] The times are very erratic. It seems to boil down to whether the process executes within one timeslice of the processor or not: there are definite quanta to the amount of time taken. Nevertheless, sometimes people may care about 0.06 seconds of startup time (certainly less non-negligible than 4 usec). • another intruder with the mooring in the heart of the Perl	[reply] [d/l]