Re^2: perl process slower and slower when loop number increase

you can count startup time like this, just do nothing:

$ time perl -e ''

real    0m0.003s
user    0m0.000s
sys 0m0.000s

$ time php -r ''

real    0m0.023s
user    0m0.020s
sys 0m0.000s
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perl always have faster startup time

but if using $i = 100000000 where perl 7secs vs PHP 1.6secs, then the problem is not startup time

the "problem" is on perl loop, or there limit of the loop number that perl "want" to handle, thats why, I try to ask how to set the loop limit. (maybe system limit or some ENV)

note: this varian loop have same result

$ time perl -e 'for($i=0;$i<=1000;$i++){for($j=0;$j<=1000;$j++){for($k
+=0;$k<=100;$k++){}}}'

real    0m7.867s
user    0m7.860s
sys 0m0.000s

$ time php -r 'for($i=0;$i<=1000;$i++){for($j=0;$j<=1000;$j++){for($k=
+0;$k<=100;$k++){}}}'

real    0m1.717s
user    0m1.712s
sys 0m0.000s
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in my vps, seem the limit is about 100k, beyond this, perl start slowing

note: if we not include startup time at above code, 
at 100k PHP and Perl have almost similiar performance

$ time perl -e 'for($i=0;$i<=100000;$i++){}'

real    0m0.010s
user    0m0.008s
sys 0m0.000s

$ time php -r 'for($i=0;$i<=100000;$i++){}'

real    0m0.030s
user    0m0.016s
sys 0m0.012s
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Re^3: perl process slower and slower when loop number increase by Dallaylaen (Chaplain) on Jan 22, 2018 at 15:59 UTC
`for ($i=0; $i<1; $i++);` is a better null statement because the parsing time would be exactly the same. And running 1 iteration of a loop (or 100 for that matter) is negligible.	[reply]