Thread: spawnl function under windows

trying to get pid of child process from the parent process

the return of _spawn function should give the created process id,

but according to below code,
child pid=13328
and return of _spawnl function is 216

explanation is appreciated

thanks

Code:

#include<stdio.h>
#include<process.h>


int main(void)
{
  printf("Spawning child with spawnl\n");
  long pid;
  pid = _spawnl( P_NOWAIT, "child.exe", "child.exe", "process_1",  "50000", NULL );
  printf("parent= %ld child=%ld ", getpid(), pid);
  return 0;
}

output:
Spawning child with spawnl
parent= 216 child=196
Process returned 0 (0x0) execution time : 0.034 s
Press any key to continue.
process_1 start with 50000 delay pid=13328

Originally Posted by Salem

Is this within MinGW or Cygwin?

What's the source code for child.exe look like?

_spawnl, _wspawnl | Microsoft Docs

A process handle is not the same as a process ID.

ok .. how to get the pid of child

the child code

Code:

// child process program
#include <stdio.h>
#include <time.h>
#include <stdlib.h> // needed for atoi


void delay(int milliseconds);


int main(int argc, char *argv[] )
{


  printf("%s start with %d delay pid=%d\n",argv[1], atoi(argv[2]), _getpid());
  delay(atoi(argv[2]));
  printf("%s end\n",argv[1]);
  return 0;
}


void delay(int milliseconds)
{
    long pause;
    clock_t now,then;


    pause = milliseconds*(CLOCKS_PER_SEC/1000);
    now = then = clock();
    while( (now-then) < pause )
        now = clock();
}

using codeblocks with MinGW

what header to include in my program to use GetProcessId function

Thanks, I saw that but I could not find processthreadsapi.h in my codeblocks+ MinGW installation

used #include <windows.h>
but still GetProcessId not defined

what i am trying to do is:


parent program tocreate ~50 calls to external program, but do not want to make 50concurrent spwanl calls, I want make ~ 5 calls at a time. then,parent program check terminated processes to make extra calls.


I need to find away, so parent program can polls created spawns, once any iscompleted, parent will make extra spawnl calls.


my hope that, I willfind a function to check the stats of a process based on it ID. onceI know a process is completed will make more spawn calls.


I think, toaccomplish this, I need
1. function gives mecreated process ID
2. function checksthe status of process based on its ID




do not know how todo (1) and (2) ?


help please.
Thanks

I have the latest codeblocks codeblocks-17.12mingw-setup.exe from their website and not sure what is the MinGW version