Liunx 線程交換打印訊息
本帖最后由 shihyu 于 2016-05-15 08:27 编辑#include <android/sensor.h>
#include <gui/Sensor.h>
#include <gui/SensorManager.h>
#include <gui/SensorEventQueue.h>
#include <utils/Looper.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/syscall.h>
#define gettid() syscall(__NR_gettid)
using namespace android;
static int g_Flag = 1;
void* thread2_fun(void* args) {
while (1) {
if (g_Flag != 1) {
continue;
}
printf("thread2_fun g_Flag=%d, g_Flag addr=%p\n",
g_Flag, &g_Flag);
g_Flag = 2;
}
}
void* thread1_fun(void* args)
{
while (1) {
if (g_Flag != 2) {
continue;
}
printf("thread1_fun g_Flag=%d, g_Flag addr=%p\n",
g_Flag, &g_Flag);
g_Flag = 1;
}
}
int main(int argc, char** argv)
{
pthread_t thread1;
pthread_t thread2;
pthread_create(&thread1, NULL, thread1_fun, NULL);
pthread_create(&thread2, NULL, thread2_fun, NULL);
pthread_join(thread1, NULL);
pthread_join(thread2, NULL);
return 0;
}在linux 上正常不断交错打印下面这两行
thread2_fun g_Flag=1, g_Flag addr=0x557a133008
thread1_fun g_Flag=2, g_Flag addr=0x557a133008
但android 手机上跑这两thread无法用g_Flag控制交错打印讯息
只印出就下面两行没了
thread2_fun g_Flag=1, g_Flag addr=0x557a133008
thread1_fun g_Flag=2, g_Flag addr=0x557a133008
我没使用sleep 也没 block 问题, 就是g_Flag
没成立就一直在绕回圈 , 一直想不明白会什么只能印这两行就没了
请问这可能是什么原因？ 还是android 上 while 空转会造成 cpu busy ,
kernel 会对这两个thread 做什么处理？
谢谢 g_Flag前加个volatile修饰试试
页:
[1]