c - 停止子进程重复输出而不杀死
问题描述
我有一个父进程，它接收可以创建子进程的用户输入，然后通过进一步的输入来操作单个子进程。
应该打印的内容如下：
New Locker Created: 1
New Locker Created: 2
New Locker Created: 3
New Locker Created: 4
New Locker Created: 5
但相反，我收到以下内容：
New Locker Created: 1
New Locker Created: 2
New Locker Created: 3
New Locker Created: 4
New Locker Created: 5
New Locker Created: 5
New Locker Created: 4
New Locker Created: 5
New Locker Created: 5
New Locker Created: 3
New Locker Created: 4
New Locker Created: 5
这会持续几行，但这就是想法。据我了解，这是因为子进程继续执行，因为父进程在接收新输入时一直在等待其他子进程完成。这个对吗？
这是我的代码：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include "locker.h"
#include <signal.h>
#include <stdarg.h>
#define P1_READ 0
#define P2_WRITE 1
#define P2_READ 2
#define P1_WRITE 3
#define NUM_PIPES 2
pid_t this_pid;
int main(){
char buffer[100];
int locker_count = 0;
int fd[2*NUM_PIPES];
int len = 0, i;
pid_t pid_list[100], wpid;
memset(pid_list,0,100);
pid_t this_pid;
struct locker_t new_locker = { .id = 0, .user_id = 0, .locked = 1, .owned = 0};
fflush(stdout);
while(1){
scanf("%s", buffer);
fflush(stdout);
if(strcmp(buffer, "CREATE") == 0){
for(i = 0; i < NUM_PIPES; ++i){
if(pipe(fd+(i*2)) < 0){
perror("Failed to allocate pipes");
exit(EXIT_FAILURE);
}
}
fflush(stdout);
this_pid = fork();
if(this_pid == 0){
//close descriptors we don't need in this process
close(fd[P1_READ]);
close(fd[P1_WRITE]);
len = read(fd[P2_READ], &locker_count, sizeof(locker_count));
//increase by 1
locker_count++;
//create locker
new_locker.id = locker_count;
printf("New Locker Created: %d\n", locker_count);
printf("\n");
write(fd[P2_WRITE], &locker_count, sizeof(locker_count));
//finished. close remaning descriptors
close(fd[P2_READ]);
close(fd[P2_WRITE]);
//need to stop this process for further executing
}
if(this_pid > 0){
//close unneeded descriptors
close(fd[P2_READ]);
close(fd[P2_WRITE]);
write(fd[P1_WRITE], &locker_count, sizeof(locker_count));
//now wait for response
len = read(fd[P1_READ], &locker_count, sizeof(locker_count));
//pid_list[(locker_count-1)] = this_pid;
close(fd[P1_READ]);
close(fd[P1_WRITE]);
fflush(stdout);
while ((wpid = waitpid(this_pid, NULL, 0)) > 0);
}
}
if(strcmp(buffer, "QUIT") == 0){
break;
exit(0);
}
}
}
谢谢你的帮助 ：）