Does each thread is created as a different process?

2 Answers

DH04 2020-12-25

Different from PC OS，it's hard to describe the rt-thread's thread is a process or a sub-threads, these points may help you understand it:

different thread in rt-thread share the same memory space, so the global variable and other ram space are accessible between threads
each thread has its own context, so the general registers, local variables, are separated

varun 2020-12-25

int data=1;

static void thread1_entry(void* parameter)
{   rt_pin_mode(LED0_PIN, PIN_MODE_OUTPUT);
    while (1)
    {
        while(data==1)
        {
            rt_pin_write(LED0_PIN, PIN_HIGH);
            rt_thread_mdelay(500);
            rt_pin_write(LED0_PIN, PIN_LOW);
            rt_thread_mdelay(500);
            data=2;
        }
    }

}

static void thread2_entry(void* parameter)
{
    rt_pin_mode(LED1_PIN, PIN_MODE_OUTPUT);
    rt_tick_t tick;

    tick = rt_tick_get();
    while (1)
    {
          while(data==2)
             {
                rt_pin_write(LED1_PIN, PIN_HIGH);
                rt_thread_mdelay(500);
                rt_pin_write(LED1_PIN, PIN_LOW);
                rt_thread_mdelay(500);
                data=1;
              }
    }
}

varun 2020-12-25

@DH04 The above part of the code is the code I am using the variable data is declared in global. After the thread1 the thread2 is not running. But usually I work like this in PC OS.

varun 2020-12-27

@DH04 What scheduling technique is used for multi-threads. ?

luckydarcy 2020-12-28

@varun 8, 32 or 256 priority scheduling multi-thread scheduling. And using the round-robin policy ensures that all threads having the same priority level will be scheduled equally.

luckydarcy 2020-12-28

So please check the priority and tick parameters of both the thread1 and thread2.

Or so you could try to add some delay after while like this:

    while (1)
    {
          while(data==/* 1 or 2 */)
          {
                /* pass... */
          }
          rt_thread_mdelay(1);
    }

DH04 2020-12-28

@varun ，as @luckydarcy said， your code may has some logic problems，in thread1_entry and thread2_entry ，you didn't give up the cpu if the condition not met， so the problem will disappear if you can ensure the process will give up the cpu wheathre the data==1 or not