Very Computer

I have encountered a strange problem with semaphores.

I'm trying to synchronize several writer-processes which write to a
shared-memory-segment.
therefore they are able to lock their write-procedure via a binary
semaphore. the problem
is when one of the servers terminates, the oncetime binary-semaphore
gets incremented to something
greater then 1.

I've tried to change the sem_flg flag of the sembuf structure, with no
success.

Any hints????

TIA

Andre

<snip>

int Writer::Run()throw(SemaphoreError){

        int i;
        pid_t pid = getpid();
        semun arg;

        struct sembuf sop_acquire,              //sembuf-struct zur
Dekrementierung der Semaphore
                      sop_release;              //sembuf-struct zur
Inkrementierung der Semaphore

        semun semun_arg;
        //Initialisierung der sembuf-struktur sop_acquire
        sop_acquire.sem_num = WAS;
        sop_acquire.sem_op = -1;
        sop_acquire.sem_flg = SEM_UNDO;

        sop_release.sem_num = WAS;
        sop_release.sem_op = 1;
        sop_release.sem_op = SEM_UNDO;

        while (1){

#ifdef _DEBUG
                cout << "Before Acquiring: " <<
semctl(semid,WAS,GETVAL,arg) << endl << flush;
#endif
                if(semop(semid,&sop_acquire,1)==-1){
                        throw SemaphoreError();
                    };
#ifdef _DEBUG
                cout << "Locked State    : " <<
semctl(semid,WAS,GETVAL,arg) << endl << flush;
#endif

//BEGIN kritischer Abschnitt

                (*db) = i = (rand()%20);

                cout << pid << ": Just wrote " << (*db) << " into
database\n";
                cout << "Reader_Semaphore : " <<
semctl(semid,RES,GETVAL,semun_arg) << " Writer-Semaphore : " <<
semctl(semid,WRS,GETVAL,semun_arg) << endl;

//ENDE kritischer Abschnitt

                if(semop(semid,&sop_release,1)==-1){
                        throw SemaphoreError();
                };              
#ifdef _DEBUG
                cout << "After Release   : "
<<semctl(semid,WAS,GETVAL,arg) << endl << flush;
#endif

                sleep(i%2);
            };
        return (1);

Quote:}

</snip>