【发布时间】：2011-08-04 05:32:51
【问题描述】：
当我在 Linux 上有两个不同的 IPC 消息队列时，有时会抓取来自错误队列的消息。
以下玩具程序显示问题，可以在不同的处理器上重复。
非常感谢任何帮助！
伯特
/*
To compile;
gcc MM.c -o mm -fno-stack-protector -pthread
We want Mickey to send a message to Minnie exclusively.
We want Donald to send a message to pluto exclusively.
Problem: Pluto intercepts Minnie's messages.
Listing gives:
$ ./mm
Mickey thread successfully started.
Minnie thread successfully started.
Pluto thread successfully started.
Donald thread successfully started.
Donald sent a message to Pluto.
Mickey sent a message to Minnie.
Pluto received: Sit, Pluto!
Minnie received: Hello, Minnie!
Mickey sent a message to Minnie. (100 times)
Pluto received: Hello, Minnie!
*/
#include <sys/types.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#include <string.h>
#include <stdio.h>
pthread_t t1,t2,t3,t4;
// Mickey send
key_t ipcMickey;
int mqMickeyid;
char helloMickeymsg[] = {"Hello, Minnie!"};
struct { long type; char text[100]; } myMickeymsg;
// Minnie get
int mqMinnieid;
struct { long type; char text[100]; } myMinniemsg;
// Donald send
key_t ipcDonald;
int mqDonaldid;
char helloDonaldmsg[] = {"Sit, Pluto!"};
struct { long type; char text[100]; } myDonaldmsg;
// Pluto get
int mqPlutoid;
struct { long type; char text[100]; } myPlutomsg;
static void * DONALDthreadFunc(void *arg)
{
printf("Donald thread successfully started.\n");
char *s = (char *) arg;
while(1)
{
//send
memset(myDonaldmsg.text, 0, 100);
strncpy(myDonaldmsg.text, helloDonaldmsg, strlen(helloDonaldmsg));
myDonaldmsg.type = 1;
msgsnd(mqDonaldid, &myDonaldmsg, sizeof(myDonaldmsg), 0);
printf("Donald sent a message to Pluto.\r\n");
sleep(4);
}
/* just a formality */
return (void *) strlen(s);
}
static void * PLUTOthreadFunc(void *arg)
{
printf("Pluto thread successfully started.\n");
char *s = (char *) arg;
while(1)
{
//receive
mqPlutoid = msgget(ipcDonald, 0);
msgrcv(mqPlutoid, &myPlutomsg, sizeof(myPlutomsg), 0, 0);
printf("Pluto received: %s\r\n\r\n", myPlutomsg.text);
sleep(1);
}
/* just a formality */
return (void *) strlen(s);
}
static void * MICKEYthreadFunc(void *arg)
{
printf("Mickey thread successfully started.\n");
char *s = (char *) arg;
while(1)
{
//send
memset(myMickeymsg.text, 0, 100);
strncpy(myMickeymsg.text, helloMickeymsg, strlen(helloMickeymsg));
myMickeymsg.type = 1;
msgsnd(mqMickeyid, &myMickeymsg, sizeof(myMickeymsg), 0);
printf("Mickey sent a message to Minnie.\r\n");
usleep(10000);
}
/* just a formality */
return (void *) strlen(s);
}
static void * MINNIEthreadFunc(void *arg)
{
printf("Minnie thread successfully started.\n");
char *s = (char *) arg;
while(1)
{
//receive
mqMinnieid = msgget(ipcMickey, 0);
msgrcv(mqMinnieid, &myMinniemsg, sizeof(myMinniemsg), 0, 0);
printf("Minnie received: %s\r\n\r\n", myMinniemsg.text);
sleep(3);
}
return (void *) strlen(s);
}
int main (void)
{
ipcMickey = ftok("/tmp/mqmickey", 63);
mqMickeyid = msgget(ipcMickey, IPC_CREAT | 0666);
ipcDonald = ftok("/tmp/mqdonald", 69);
mqDonaldid = msgget(ipcDonald, IPC_CREAT | 0666);
pthread_create(&t1, NULL, MICKEYthreadFunc, "Mickey sends\n");
pthread_create(&t2, NULL, MINNIEthreadFunc, "Minnie replies\n");
pthread_create(&t3, NULL, DONALDthreadFunc, "Donald sends\n");
pthread_create(&t4, NULL, PLUTOthreadFunc, "Pluto replies\n");
while(1)
{
sleep(5);
}
}
【问题讨论】：
-
+1 用于编译最小示例，将进行测试