RT-Thread的互斥量优先级问题求解

RT Thread优先级问题，官网视频，互斥量一节，明明是线程2的优先级比线程1高，但线程1会优先运行，不知是有什么机理还是Bug？

经反复测试发现，将线程优先级配置到接近线程优先级的最大范围吋，比如优先级最大值25，线程优先级设置为21一25都可恢复正常功能，即高优先级先运行。

源代码如下：

/*

Copyright (c) 2006-2018, RT-Thread Development Team

SPDX-License-Identifier: Apache-2.0

Change Logs:
Date Author Notes
2018-08-24 yangjie the first version
/
/ 程序清单：互斥锁例程

互斥锁是一种保护共享资源的方法。当一个线程拥有互斥锁的时候，
可以保护共享资源不被其他线程破坏。线程1对2个number分别进行加1操作
线程2也会对2个number分别进行加1操作。使用互斥量保证2个number值保持一致
/
#include <rtthread.h>
#define THREAD_PRIORITY 8
#define THREAD_TIMESLICE 5
/ 指向互斥量的指针 */
static rt_mutex_t dynamic_mutex = RT_NULL;
static rt_uint8_t number1,number2 = 0;
ALIGN(RT_ALIGN_SIZE)
static char thread1_stack[1024];
static struct rt_thread thread1;
static void rt_thread_entry1(void parameter)
{
while(1)
{
/ 线程1获取到互斥量后，先后对number1、number2进行加1操作，然后释放互斥量 */
rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
number1++;
rt_thread_mdelay(10);
number2++;
rt_mutex_release(dynamic_mutex);
}
}
ALIGN(RT_ALIGN_SIZE)
static char thread2_stack[1024];
static struct rt_thread thread2;
static void rt_thread_entry2(void parameter)
{
while(1)
{
/ 线程2获取到互斥量后，检查number1、number2的值是否相同，相同则表示mutex起到了锁的作用 /
rt_mutex_take(dynamic_mutex, RT_WAITING_FOREVER);
if(number1 != number2)
{
rt_kprintf("not protect.number1 = %d, mumber2 = %d \n",number1 ,number2);
}
else
{
rt_kprintf("mutex protect ,number1 = mumber2 is %d\n",number1);
}
number1++;
number2++;
rt_mutex_release(dynamic_mutex);
if(number1 >=50)
return;
}
}
/ 互斥量示例的初始化 /
int mutex_sample(void)
{
/ 创建一个动态互斥量 /
dynamic_mutex = rt_mutex_create("dmutex", RT_IPC_FLAG_FIFO);
if (dynamic_mutex == RT_NULL)
{
rt_kprintf("create dynamic mutex failed.\n");
return -1;
}
rt_thread_init(&thread1,
"thread1",
rt_thread_entry1,
RT_NULL,
&thread1_stack[0],
sizeof(thread1_stack),
THREAD_PRIORITY, THREAD_TIMESLICE);
rt_thread_startup(&thread1);
rt_thread_init(&thread2,
"thread2",
rt_thread_entry2,
RT_NULL,
&thread2_stack[0],
sizeof(thread2_stack),
THREAD_PRIORITY-1, THREAD_TIMESLICE);
rt_thread_startup(&thread2);
return 0;
}
/ 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(mutex_sample, mutex sample);