message-queue 相关问题

父母有“m”条消息要发送给“n”个孩子。在每次迭代中，它向所有子节点发送一条消息。如果所有回复“已收到”，它会发送下一条消息。下面是我的代码 #包括父母有“m”条消息要发送给“n”个孩子。在每次迭代中，它向所有子节点发送一条消息。如果所有回复“已收到”，它会发送下一条消息。下面是我的代码 #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> #include <sys/wait.h> #include <stdio.h> #include <string.h> #include <signal.h> #include <stdlib.h> #include <unistd.h> #define MAX_LEN 50 struct details { int no; int id; char msg_text[MAX_LEN]; }; typedef struct msg_buf { long int msg_type; struct details d; } msg; char message[20][50] = { " ", "Message1", "Message2", "Message3", "Message4", "Message5", "Message6", "Message7", "Message8" }; int main(int argc, char *argv[]) { int id1, id2, n, m, i, j, status, p_id; pid_t pid; msg snd, rcvd; if (argc < 2) { perror("Too few arguments"); return -1; } n = atoi(argv[1]); m = atoi(argv[2]); id1 = msgget((key_t)78, IPC_CREAT | 0666); id2 = msgget((key_t)56, IPC_CREAT | 0666); if (id1 == -1 || id2 == -1) { printf("Error in creating message queue\n"); return -1; } p_id = getpid(); printf("\nQueues are created.\n\n"); for (i = 1; i <= n; i++) { pid = fork(); if (pid == 0) break; } if (pid == 0) { for (j = 1; j <= m; j++) { printf("Process %d waiting for message %d\n", getpid(), j); while (msgrcv(id1, &rcvd, sizeof(struct details), j + 1, IPC_NOWAIT) < 0) { } srand(time(0)); strcpy(snd.d.msg_text, "Received"); snd.msg_type = rcvd.msg_type; snd.d.no = rcvd.d.no; snd.d.id = getpid(); if (msgsnd(id2, &snd, sizeof(struct details), IPC_NOWAIT) < 0) { perror("msgsnd"); } else { printf("Reply sending successful for message %d for process %d\n", snd.d.no, snd.d.id); } } } if (p_id == getpid()) { for (j = 1; j <= m; j++) { strcpy(snd.d.msg_text, message[j]); snd.msg_type = j + 1; snd.d.no = j; if (msgsnd(id1, &snd, sizeof(struct details), 0) < 0) { perror("msgsnd"); } else { printf("Message %d sent- \t\t\t\t%s\n", j, snd.d.msg_text); } for (i = 1; i <= n; i++) { sleep(i); if (msgrcv(id2, &rcvd, sizeof(struct details), j + 1, 0) >= 0) { printf("Reply received from child %d for message %d - \t%s\n", rcvd.d.id, j, rcvd.d.msg_text); } } } wait(NULL); printf("Communication End.\n\n"); } } 我得到的输出是n=2，m=2是： Queues are created. Message 1 sent- Message1 Process 14804 waiting for message 1 Process 14805 waiting for message 1 Reply sending successful for message 1 for process 14804 Process 14804 waiting for message 2 Reply received from child 14804 for message 1 - Received 此后什么也没有打印。没有任何进展。问题是什么？如何解决这个问题？最大的单一问题是在评论中提到的一个： AFAICS，您每次迭代发送一条消息，因此最多一个孩子可以阅读它。您不会向每个孩子发送一条消息。任何给定的消息都可以被（最多）一个进程接收。对于 n 进程接收消息，您必须发送 n 消息。其他问题主要是装饰性的。我使用了 GitHub 上我的 SOQ（堆栈溢出问题）存储库中可用的日志记录代码作为文件 stderr.c 和 stderr.h 在 src/libsoq 子目录中。一些消息被写入 stdout — 没有只接受文件流的函数，所以我使用 err_logmsg() 接受文件流、控制选项和退出状态（但函数不应该退出，所以这是未使用的）以及格式和参数。结果是： /* SO 7592-2454 */ #include <errno.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ipc.h> #include <sys/msg.h> #include <sys/wait.h> #include <unistd.h> #include "stderr.h" #define MAX_LEN 50 struct details { int no; int id; char msg_text[MAX_LEN]; }; typedef struct msg_buf { long int msg_type; struct details d; } msg; static char message[20][50] = { " ", "Message1", "Message2", "Message3", "Message4", "Message5", "Message6", "Message7", "Message8" }; static const char usestr[] = "num_kids num_msgs"; static void dump_message(const char *tag, const msg *info) { err_logmsg(stdout, err_getlogopts(), 0, "%s: type %ld (details: no %d, id %d, text [%s])\n", tag, info->msg_type, info->d.no, info->d.id, info->d.msg_text); } int main(int argc, char *argv[]) { err_setarg0(argv[0]); if (argc != 3) err_usage(usestr); int n = atoi(argv[1]); int m = atoi(argv[2]); int id1 = msgget((key_t)78, IPC_CREAT | 0666); int id2 = msgget((key_t)56, IPC_CREAT | 0666); if (id1 == -1 || id2 == -1) err_syserr("failed to create a message queue: "); pid_t p_id = getpid(); err_setlogopts(ERR_PID|ERR_MILLI); err_logmsg(stdout, err_getlogopts(), 0, "Queues are created.\n"); pid_t pid; for (int i = 1; i <= n; i++) { pid = fork(); if (pid == 0) break; } msg snd; msg rcvd; if (pid == 0) { for (int j = 1; j <= m; j++) { err_logmsg(stdout, err_getlogopts(), 0, "Waiting for message %d\n", j); while (msgrcv(id1, &rcvd, sizeof(struct details), j + 1, IPC_NOWAIT) < 0) err_syserr("msgrcv() returned with error status: "); dump_message("Message received", &rcvd); strcpy(snd.d.msg_text, "Received"); snd.msg_type = rcvd.msg_type; snd.d.no = rcvd.d.no; snd.d.id = getpid(); if (msgsnd(id2, &snd, sizeof(struct details), IPC_NOWAIT) < 0) err_sysrem("msgsnd() failed: "); else dump_message("Message sent", &snd); } err_logmsg(stdout, err_getlogopts(), 0, "Child process complete\n"); exit(EXIT_SUCCESS); } if (p_id == getpid()) { for (int j = 1; j <= m; j++) { strcpy(snd.d.msg_text, message[j]); snd.msg_type = j + 1; snd.d.no = j; for (int i = 0; i < n; i++) { if (msgsnd(id1, &snd, sizeof(struct details), 0) < 0) err_sysrem("msgsnd() failed: "); else dump_message("Message sent", &snd); } for (int i = 1; i <= n; i++) { err_logmsg(stdout, err_getlogopts(), 0, "Dozing for %d seconds\n", i); sleep(i); if (msgrcv(id2, &rcvd, sizeof(struct details), j + 1, 0) >= 0) dump_message("Reply received", &rcvd); else err_syserr("msgrcv() failed: "); } } int corpse; int status; while ((corpse = wait(&status)) > 0) err_remark("Child %d exited with status 0x%.4X\n", corpse, status); err_logmsg(stdout, err_getlogopts(), 0, "Communication End.\n\n"); } return 0; } 有大量的日志记录，因为我需要看看发生了什么。代码应该验证 n 和 m 的值（它们应该至少是 1 并且不超过一些微弱的理智数字（例如 10，但会有一个或两个值（枚举或定义常数）来限制可接受的范围。这是一个示例输出（源代码msg79.c，程序msg79）： $ ./msg79 2 3 msg79: 2023-04-03 21:36:38.215 - pid=67247: Queues are created. msg79: 2023-04-03 21:36:38.217 - pid=67247: Message sent: type 2 (details: no 1, id 1, text [Message1]) msg79: 2023-04-03 21:36:38.217 - pid=67247: Message sent: type 2 (details: no 1, id 1, text [Message1]) msg79: 2023-04-03 21:36:38.217 - pid=67247: Dozing for 1 seconds msg79: 2023-04-03 21:36:38.217 - pid=67248: Waiting for message 1 msg79: 2023-04-03 21:36:38.217 - pid=67249: Waiting for message 1 msg79: 2023-04-03 21:36:38.217 - pid=67248: Message received: type 2 (details: no 1, id 1, text [Message1]) msg79: 2023-04-03 21:36:38.217 - pid=67249: Message received: type 2 (details: no 1, id 1, text [Message1]) msg79: 2023-04-03 21:36:38.217 - pid=67248: Message sent: type 2 (details: no 1, id 67248, text [Received]) msg79: 2023-04-03 21:36:38.217 - pid=67248: Waiting for message 2 msg79: 2023-04-03 21:36:38.217 - pid=67249: Message sent: type 2 (details: no 1, id 67249, text [Received]) msg79: 2023-04-03 21:36:38.218 - pid=67248: Message received: type 3 (details: no 2, id 1, text [Message2]) msg79: 2023-04-03 21:36:38.218 - pid=67249: Waiting for message 2 msg79: 2023-04-03 21:36:38.218 - pid=67249: Message received: type 3 (details: no 2, id 1, text [Message2]) msg79: 2023-04-03 21:36:38.218 - pid=67248: Message sent: type 3 (details: no 2, id 67248, text [Received]) msg79: 2023-04-03 21:36:38.218 - pid=67249: Message sent: type 3 (details: no 2, id 67249, text [Received]) msg79: 2023-04-03 21:36:38.218 - pid=67248: Waiting for message 3 msg79: 2023-04-03 21:36:38.219 - pid=67249: Waiting for message 3 msg79: 2023-04-03 21:36:38.219 - pid=67248: Message received: type 4 (details: no 3, id 1, text [Message3]) msg79: 2023-04-03 21:36:38.219 - pid=67249: Message received: type 4 (details: no 3, id 1, text [Message3]) msg79: 2023-04-03 21:36:38.219 - pid=67248: Message sent: type 4 (details: no 3, id 67248, text [Received]) msg79: 2023-04-03 21:36:38.219 - pid=67249: Message sent: type 4 (details: no 3, id 67249, text [Received]) msg79: 2023-04-03 21:36:38.219 - pid=67248: Child process complete msg79: 2023-04-03 21:36:38.219 - pid=67249: Child process complete msg79: 2023-04-03 21:36:39.219 - pid=67247: Reply received: type 2 (details: no 1, id 67248, text [Received]) msg79: 2023-04-03 21:36:39.219 - pid=67247: Dozing for 2 seconds msg79: 2023-04-03 21:36:41.220 - pid=67247: Reply received: type 2 (details: no 1, id 67249, text [Received]) msg79: 2023-04-03 21:36:41.220 - pid=67247: Message sent: type 3 (details: no 2, id 1, text [Message2]) msg79: 2023-04-03 21:36:41.220 - pid=67247: Message sent: type 3 (details: no 2, id 1, text [Message2]) msg79: 2023-04-03 21:36:41.220 - pid=67247: Dozing for 1 seconds msg79: 2023-04-03 21:36:42.221 - pid=67247: Reply received: type 3 (details: no 2, id 67248, text [Received]) msg79: 2023-04-03 21:36:42.221 - pid=67247: Dozing for 2 seconds msg79: 2023-04-03 21:36:44.223 - pid=67247: Reply received: type 3 (details: no 2, id 67249, text [Received]) msg79: 2023-04-03 21:36:44.223 - pid=67247: Message sent: type 4 (details: no 3, id 1, text [Message3]) msg79: 2023-04-03 21:36:44.223 - pid=67247: Message sent: type 4 (details: no 3, id 1, text [Message3]) msg79: 2023-04-03 21:36:44.223 - pid=67247: Dozing for 1 seconds msg79: 2023-04-03 21:36:45.227 - pid=67247: Reply received: type 4 (details: no 3, id 67248, text [Received]) msg79: 2023-04-03 21:36:45.227 - pid=67247: Dozing for 2 seconds msg79: 2023-04-03 21:36:47.227 - pid=67247: Reply received: type 4 (details: no 3, id 67249, text [Received]) msg79: 2023-04-03 21:36:47.227 - pid=67247: Child 67249 exited with status 0x0000 msg79: 2023-04-03 21:36:47.227 - pid=67247: Child 67248 exited with status 0x0000 msg79: 2023-04-03 21:36:47.228 - pid=67247: Communication End. $

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