Performances comparission between 5.1 and 5.2.

[felix]

Configuration Information:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2
uname output: Linux medium 5.10.0-12-amd64 #1 SMP Debian 5.10.103-1 
(2022-03-07) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2
Patch Level: 0
Release Status: rc2

Description:
        Trying some script under 5.2 beta, rc1 and rc2, I was surprised by 
execution time.
        In order to compare, I've tried to establish execution time of 
elementar operations, like:

         - {0..999}    .`: {0..999}`
         - 3x{0..9}     `: {0..9}{0..9}{0..9}`
         - readUt       `read -r ut idl </proc/uptime`
         - RE           `[[ $cnt =~ ^[0-9]*\..*$ ]]`
         - InLneStr     `: <<<"Hello world!"`
         - IncInt       `int+=1`
         - AccessRt     `: "$EPOCHREALTIME"`
         - PrintF       `printf -v int '%s+%s' $int 1`

        Here is results of my comparission between different version of bash:
        (1st column show number of empty loop in 0.2 seconds as reference)
        $ for((i=0;i<${#bashs[@]};i++)){ ${bashs[i]} timedTest.sh 
${args[i]:--q};}
              l/.2s    {0..999}    3x{0..9}      readUt          RE    InLneStr 
     IncInt    AccessRt      PrintF  Version            BuildDir
              66222      330.31      338.28       13.17       19.02       63.16 
       0.08        2.69        1.18  5.0.17(1)-release  /tmp/bash/bash-5.0/bash
              73720      366.97      379.70       13.20       17.80       10.09 
       0.10        2.46        1.19  5.1.4(1)-release   /bin/bash
              60585      409.92      419.53       13.62       19.87       10.87 
       0.09        3.00        1.38  5.1.4(1)-release   
/tmp/bash/bash-5.1.4/bash
              62416      417.85      423.23       14.63       20.84       11.34 
       0.36        3.05        1.43  5.1.4(1)-release   
/tmp/bash/bash-5.1.4/bash_dynlib
              62538      416.97      439.28       13.65       20.69       12.51 
       0.29        3.05        1.57  5.1.4(1)-release   
/tmp/bash/debian/bash-5.1/bash
              60664      419.54      425.89       14.25       21.05       11.01 
       0.57        3.12        1.38  5.1.16(1)-release  
/tmp/bash/bash-5.1.16/bash
              40808    39995.10    39995.10       18.49       35.46       15.65 
       0.34        5.81        2.40  5.2.0(1)-beta      
/tmp/bash/bash-5.2-beta/bash
              40134    33328.35    39995.02       18.88       31.18       14.73 
       0.29        6.19        2.20  5.2.0(1)-rc1       
/tmp/bash/bash-5.2-rc1/bash
              40350    39995.04    39995.04       19.10       32.20       14.66 
       0.59        6.15        2.26  5.2.0(1)-rc2       
/tmp/bash/bash-5.2-rc2/bash

        Where if everything seem slower, accessing $EPOCHREALTIME like `prinf 
-v INTEGER '%s+%s' $INTEGER 1` or
        using Regular Expression use approx 2x more time, but a sequence of 
1000 using brace expansion require 100x more time!!

        Another test (first script I wrote) is something slower, but render 
approx same results:
        $ for((i=0;i<${#bashs[@]};i++)){ ${bashs[i]} looptest.sh 
${args[i]:--q};}
             l/.02s    {0..999}    3x{0..9}      readUt          RE    InLneStr 
     IncInt    AccessRt      PrintF  Version            BuildDir
               1468      340.47      348.36       16.71       22.54       51.44 
       1.71        5.10        3.51  5.0.17(1)-release  bash-5.0/bash
               1714      366.64      380.21       15.11       20.11       12.23 
       1.33        3.99        2.35  5.1.4(1)-release   /bin/bash
               1074      414.53      423.91       15.91       22.94       12.78 
       1.72        4.77        2.54  5.1.4(1)-release   bash-5.1.4/bash
               1444      413.59      418.95       16.80       22.83       13.21 
       1.70        4.71        2.51  5.1.4(1)-release   bash-5.1.4/bash_dynlib
               1360      421.20      432.83       16.33       22.79       12.98 
       1.82        4.87        2.59  5.1.4(1)-release   debian/bash-5.1/bash
               1134      420.00      428.62       16.76       22.74       13.12 
       1.78        4.92        2.60  5.1.16(1)-release  bash-5.1.16/bash
                687    40158.21    40676.12       23.73       38.81       18.98 
       3.96        9.87        3.94  5.2.0(1)-beta      bash-5.2-beta/bash
                607    39559.71    40192.35       23.38       37.68       19.08 
       3.95        9.98        3.99  5.2.0(1)-rc1       bash-5.2-rc1/bash
                740    40531.76    40965.16       24.38       37.99       19.13 
       3.94       10.05        3.95  5.2.0(1)-rc2       bash-5.2-rc2/bash

Repeat-By:
        https://f-hauri.ch/vrac/timedTest.sh.txt
        https://f-hauri.ch/vrac/looptest.sh.txt

-- 
 Félix Hauri  -  <felix@f-hauri.ch>  -  http://www.f-hauri.ch