How to start multiple Processes in Contiki to create load on CPU

How can I start multiple processes in parallel to create a congestion in CPU usage? Below is the code I was trying:-

#include "contiki.h"
#include <stdio.h>

PROCESS(cpu_load_process_1, "CPU Loading Process 1");
PROCESS(cpu_load_process_2, "CPU Loading Process 2");
PROCESS(cpu_load_process_3, "CPU Loading Process 3");
PROCESS(cpu_load_process_4, "CPU Loading Process 4");

AUTOSTART_PROCESSES(&cpu_load_process_1);
AUTOSTART_PROCESSES(&cpu_load_process_2);

PROCESS_THREAD(cpu_load_process_1, ev, data)
 {
   PROCESS_BEGIN();
   PROCESS_END();
 }
 PROCESS_THREAD(cpu_load_process_3, ev, data)
 {
  PROCESS_BEGIN();
  PROCESS_END();
 }

but, this gives error as following:-

/home/user/contiki-3.0/core/./sys/autostart.h:48:24: error: redefinition of ‘autostart_processes’
struct process * const autostart_processes[] = {__VA_ARGS__, NULL}struct process * const autostart_processes[] = {__VA_ARGS__, NULL}

Please guide me through. Any alternative way/suggestion of creating CPU congestion would also be helpful.

Behind the macro AUTOSTART_PROCESSES, a structure definition is hidden.

#define AUTOSTART_PROCESSES(...)                    \
    struct process * const autostart_processes[] = {__VA_ARGS__, NULL}

By calling twice AUTOSTART_PROCESSES, you define the structure twice.

Solution:

Given the macro parameters, I guess that you should write:

AUTOSTART_PROCESSES(&cpu_load_process_1, &cpu_load_process_2);

Instead of

AUTOSTART_PROCESSES(&cpu_load_process_1);
AUTOSTART_PROCESSES(&cpu_load_process_2);