线程从队列Linux中获取其他线程IPC消息

分类：编程问答

如何解决线程从队列Linux中获取其他线程IPC消息

| 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。 以下玩具程序显示了问题，可以在不同的处理器上重复进行。 任何帮助，不胜感激！ 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,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);
        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,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);
        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,MINNIEthreadFunc,\"Minnie replies\\n\");
    pthread_create(&t3,DONALDthreadFunc,\"Donald sends\\n\");
    pthread_create(&t4,PLUTOthreadFunc,\"Pluto replies\\n\");

    while(1)
    {
        sleep(5);
    }
}
    

解决方法

问题是您错过了错误处理。 包括 
ipcMickey = ftok(\"/tmp/mqmickey\",63);
if (-1==ipcMickey)
{
    perror(\"ipcMickey\");
    exit(255);
}
ipcDonald = ftok(\"/tmp/mqdonald\",69);
if (-1==ipcDonald)
{
    perror(\"ipcDonald\");
    exit(255);
}
您很快就会发现 
./mm
ipcDonald: No such file or directory
在这种情况下，
ftok
的回报为-1。如果两个文件都丢失，则两个ipc密钥都将为-1，这意味着所有流量共享相同的端口:) 所以 
touch /tmp/mqmickey /tmp/mqdonald
解决它。一些统计数据（用ѭ5代替睡眠）： 
gcc MM.c -o mm -O3 -fno-stack-protector -pthread
time ./mm | { trap \"\" INT; sort | uniq -c | tee stats; } 
  16047 
      1 Donald sent a 
   8054 Donald sent a message to Pluto.
      1 Donald thread successfully started.
   8040 Mickey sent a message to Minnie.
      1 Mickey thread successfully started.
   8065 Minnie received: Hello,Minnie!
      1 Minnie thread successfully started.
   7982 Pluto received: Sit,Pluto!
      1 Pluto thread successfully started.


real    0m40.814s
user    0m0.168s
sys 0m0.092s
    ,非常感谢您和VJo， 这是程序的修改版本，考虑了您的所有注释。 希望这对其他人有用。 伯特 
/*
    We want Mickey to send a message to Minnie exclusively.
    We want Donald to send a message to pluto exclusively.  

    To compile:
    gcc mm.c -o mm -fno-stack-protector -pthread

    Requires: 
    syslog enabled and started.

    To test:
    time ./mm | { trap \"\" INT; sort | uniq -c | tee stats; } 

    Results:
    1503373 Donald sent a message to Pluto.
          1 Donald thread successfully started.
    1423964 Mickey sent a message to Minnie.
          1 Mickey thread successfully started.
    1423958  Minnie received: Hello,Minnie!
          1 Minnie thread successfully started.
    1503333 Pluto received: Sit,Pluto!
          1 Pluto thread successfully started.

    real    0m17.133s
    user    0m16.053s
    sys 0m5.248s

*/
#include <sys/types.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>


#define MQMICKEY \"/tmp/MQMickey\"
#define MQDONALD \"/tmp/MQDonald\"

pthread_t t1,t2,t3,t4;
FILE *fMickeypointer;
FILE *fDonaldpointer;

// 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,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\"); 
    }

    /* 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);
        printf(\"Pluto received: %s\\r\\n\",myPlutomsg.text);
    }

    /* 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,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\");
    }

    /* 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);
        printf(\" Minnie received: %s\\r\\n\",myMinniemsg.text);
    }

    return (void *) strlen(s);
}

int main (void)
{
    /* 
        MUST create the target files first.

        The return of ftok is -1 if file is missing. If BOTH files are missing,both ipc keys 
        will be -1,meaning all traffic shares the same port. Result: one queue will acquire
        messages not intended for it!
    */
    fMickeypointer = fopen(MQMICKEY,\"a\");
    if(fMickeypointer == NULL) 
    {
        printf(\"Failed to create Mickey queue file.\\n\");

        /* system logging */
        setlogmask (LOG_UPTO (LOG_NOTICE));
        openlog (\"MickeyDonald\",LOG_CONS | LOG_PID | LOG_NDELAY,LOG_LOCAL1);
        syslog (LOG_NOTICE,\"Failed to create Mickey queue file.\" );
        closelog ();
        exit(91);
    }

    fDonaldpointer = fopen(MQDONALD,\"a\");
    if(fDonaldpointer == NULL) 
    {
        printf(\"Failed to create Donald queue file.\\r\\n\");

        /* system logging */
        setlogmask (LOG_UPTO (LOG_NOTICE));
        openlog (\"MickeyDonald\",\"Failed to create Donald queue file.\" );
        closelog ();
        exit(92);
    }

    ipcMickey = 0;
    ipcDonald = 0;

    /* make sure we assign DIFFERENT ipc values */  
    while(ipcMickey == ipcDonald)
    {
        ipcMickey = ftok(MQMICKEY,63);
        if (-1==ipcMickey)
        {
            printf(\"ipcMickey does not exist.\\r\\n\");

            /* system logging */
            setlogmask (LOG_UPTO (LOG_NOTICE));
            openlog (\"MickeyDonald\",LOG_LOCAL1);
            syslog (LOG_NOTICE,\"Failed to ftok Mickey file.\" );
            closelog ();
            exit(93);
        }

        ipcDonald = ftok(MQDONALD,69);
        if (-1==ipcDonald)
        {
            printf(\"ipcDonald does not exist.\\r\\n\");

            /* system logging */
            setlogmask (LOG_UPTO (LOG_NOTICE));
            openlog (\"MickeyDonald\",\"Failed to ftok Donald file.\" );
            closelog ();
            exit(94);
        }
    }

    mqMickeyid = msgget(ipcMickey,IPC_CREAT | 0666);
    mqDonaldid = msgget(ipcDonald,IPC_CREAT | 0666);

    pthread_create(&t1,NULL,MICKEYthreadFunc,\"Mickey sends\\n\");
    pthread_create(&t2,MINNIEthreadFunc,\"Minnie replies\\n\");
    pthread_create(&t3,DONALDthreadFunc,\"Donald sends\\n\");
    pthread_create(&t4,PLUTOthreadFunc,\"Pluto replies\\n\");

    long exitcounter = 0;
    while(exitcounter < 100000)
    {
        exitcounter +=1;        
        usleep(100);
    }
    exit(0);
}
    ,这是您的程序的稍作修改的版本： 
/*
    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,t4;

// Mickey send
key_t ipcMickey;
int mqMickeyid;
char helloMickeymsg[] = {\"Hello,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);
        printf(\"Pluto received: %s\\r\\nPluto uses MQ with id = %d\\r\\n\",myPlutomsg.text,mqPlutoid);
        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);
        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);
        printf(\" Minnie received: %s\\r\\nMinnie uses MQ with id = %d\\r\\n\",myMinniemsg.text,mqMinnieid);
        sleep(3);
    }

    return (void *) strlen(s);
}

int main (void)
{
    ipcMickey = ftok(\"./mqmickey\",63);
    mqMickeyid = msgget(ipcMickey,IPC_CREAT | 0666);
    printf( \"mqMickeyid=%d\\n\",mqMickeyid);

    ipcDonald = ftok(\"./mqdonald\",69);
    mqDonaldid = msgget(ipcDonald,IPC_CREAT | 0666);
    printf( \"mqDonaldid=%d\\n\",mqDonaldid);

    pthread_create(&t1,\"Pluto replies\\n\");

    while(1)
    {
        sleep(5);
    }
}
我发现由于某种原因，“ 9”失败，并且两个MQ都具有相同的ID，这是线程首先进入的竞赛。 使用此程序的修改版本，请执行以下操作： 
touch mqmickey
touch mqdonald
首先创建文件。 并且您应该看到消息发送给正确的收件人。     

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