for and start commands in a batch for parallel and sequential work

Question

I have an 8 core CPU with 8GB of RAM, and I\'m creating a batch file to automate 7-zip CLI in exhausting most parameters and variables to compress the same set of files with

Answer 1

I've already posted a robust batch solution that limits the number of parallel processes at Parallel execution of shell processes. That script uses a list of commands that is embedded within the script. Follow the link to see how it works.

I modified that script to generate the commands using FOR loops as per your question. I also set the limit to 8 simultaneous processes.

Your maximum memory is 1g, and you never have more than 8 processes, so I don't see how you could ever exceed 8g. If you increase the max memory per processes, then you do have to worry about total memory. you will have to add additional logic to keep track of how much memory is being used, and which cpu IDs are available. Note that batch numbers are limited to ~2g, so I recommend computing memory used in megabytes.

By default, the script hides the output of the commands. If you want to see the output, then run it with the /O option.

@echo off
setlocal enableDelayedExpansion

:: Display the output of each process if the /O option is used
:: else ignore the output of each process
if /i "%~1" equ "/O" (
  set "lockHandle=1"
  set "showOutput=1"
) else (
  set "lockHandle=1^>nul 9"
  set "showOutput="
)

:: Define the maximum number of parallel processes to run.
:: Each process number can optionally be assigned to a particular server
:: and/or cpu via psexec specs (untested).
set "maxProc=8"

:: Optional - Define CPU targets in terms of PSEXEC specs
::           (everything but the command)
::
:: If a cpu is not defined for a proc, then it will be run on the local machine.
:: I haven't tested this feature, but it seems like it should work.
::
:: set cpu1=psexec \\server1 ...
:: set cpu2=psexec \\server1 ...
:: set cpu3=psexec \\server2 ...
:: etc.

:: For this demo force all cpu specs to undefined (local machine)
for /l %%N in (1 1 %maxProc%) do set "cpu%%N="

:: Get a unique base lock name for this particular instantiation.
:: Incorporate a timestamp from WMIC if possible, but don't fail if
:: WMIC not available. Also incorporate a random number.
  set "lock="
  for /f "skip=1 delims=-+ " %%T in ('2^>nul wmic os get localdatetime') do (
    set "lock=%%T"
    goto :break
  )
  :break
  set "lock=%temp%\lock%lock%_%random%_"

:: Initialize the counters
  set /a "startCount=0, endCount=0"

:: Clear any existing end flags
  for /l %%N in (1 1 %maxProc%) do set "endProc%%N="

:: Launch the commands in a loop
  set launch=1
  echo mem=1m 2m 3m 4m 6m 8m 12m 16m 24m 32m 48m 64m 96m 128m 192m 256m 384m 512m 768m 1024m
  echo o=2 3 4 5 6 7 8 10 12 14 16 20 24 28 32
  echo s=off 1m 2m 4m 8m 16m 32m 64m 128m 256m 512m 1g 2g 4g 8g 16g 32g 64g on
  echo x=1 3 5 7 9
  for %%x IN (9) DO for %%d IN (1024m 768m 512m 384m 256m 192m 128m 96m 64m 48m 32m 24m 16m 12m 8m 6m 4m 3m 2m 1m) DO (
    set "cmd=7z.exe a teste.resultado\%%xx.ppmd.%%dd.%%ww.%%ss.7z .\teste.original\* -mx=%%x -m0=PPMd:mem=%%d:o=%%w -ms=%%s"
    if !startCount! lss %maxProc% (
      set /a "startCount+=1, nextProc=startCount"
    ) else (
      call :wait
    )
    set cmd!nextProc!=!cmd!
    if defined showOutput echo -------------------------------------------------------------------------------
    echo !time! - proc!nextProc!: starting !cmd!
    2>nul del %lock%!nextProc!
    %= Redirect the lock handle to the lock file. The CMD process will     =%
    %= maintain an exclusive lock on the lock file until the process ends. =%
    start /b "" cmd /c %lockHandle%^>"%lock%!nextProc!" 2^>^&1 !cpu%%N! !cmd!
  )
  set "launch="

:wait
:: Wait for procs to finish in a loop
:: If still launching then return as soon as a proc ends
:: else wait for all procs to finish
  :: redirect stderr to null to suppress any error message if redirection
  :: within the loop fails.
  for /l %%N in (1 1 %startCount%) do (
    %= Redirect an unused file handle to the lock file. If the process is    =%
    %= still running then redirection will fail and the IF body will not run =%
    if not defined endProc%%N if exist "%lock%%%N" (
      %= Made it inside the IF body so the process must have finished =%
      if defined showOutput echo ===============================================================================
      echo !time! - proc%%N: finished !cmd%%N!
      if defined showOutput type "%lock%%%N"
      if defined launch (
        set nextProc=%%N
        exit /b
      )
      set /a "endCount+=1, endProc%%N=1"
    ) 9>>"%lock%%%N"
  ) 2>nul
  if %endCount% lss %startCount% (
    1>nul 2>nul ping /n 2 ::1
    goto :wait
  )

2>nul del %lock%*
if defined showOutput echo ===============================================================================
echo Thats all folks!

Answer 2

To execute at the same time no more than 8 instances of 7z.exe process you could do this:

@Echo OFF & Setlocal EnableDelayedExpansion

Set /A "pCount=0" & REm Process count

For
...
) DO (
     Set /A "pCount+=1"
     If !pCount! LEQ 8 (
       Start /B 7z.exe a teste.resultado\%%xx.ppmd.%%dd.%%ww.%%ss.7z .\teste.original\* -mx=%%x -m0=PPMd:mem=%%d:o=%%w -ms=%%s
     )
)
...

If do you want to run each process in a new parallel CMD window then you would replace the Start /B line on my code for this else:

CMD /C "Start /w 7z.exe a teste.resultado\%%xx.ppmd.%%dd.%%ww.%%ss.7z .\teste.original\* -mx=%%x -m0=PPMd:mem=%%d:o=%%w -ms=%%s"