关于pthreads：防死锁，随机线程执行顺序C

Deadlock Prevention, random thread execution order C

我正在为学校布置作业程序。它具有以下要求，如下所示。

必须使用Mutexes
必须使用Pthreads
创建5个具有随机同步的线程(又名：以非特定顺序运行)
线程必须与主线程分离
每个线程都将从文件中读取并调整银行帐户的余额，每个帐户都有不同的输入文件。

这是指向实际作业的链接，我们需要做些什么以获取更详细的信息集AssignmentTxtFile

我的主要问题是解决遇到的僵局问题。我不知道如何确切地解决此问题，我知道我需要找出一种方法，使其在任何给定时间都不会进入多个线程的关键部分。在保持执行顺序随机的同时，我该怎么做？

这是我目前用于该程序的代码。

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>

pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;

float balance = 0;

void *thread1(void *value){

FILE *fPTR;
char buffer;
float number;

char *fileName ="data1.in";

fPTR = fopen(fileName,"r");

if (fPTR == NULL){

printf("was unable to open: %s\
", fileName);
return NULL;
}

while(1){

//Critical Section of Thread1
pthread_mutex_lock(&mutex1);
fscanf(fPTR,"%c%f\
", &buffer, &number);

if(buffer == '+'){

balance += number;

}
if(buffer == '-'){

balance -= number;
}

printf("Account balance of thread1 is: %f\
", balance);

if(feof(fPTR)){

fclose(fPTR);
printf("end of data1.in");
return NULL;
}

printf("end of while thread1\
");
pthread_mutex_unlock(&mutex1);

sleep(.3);
}

}

void *thread2(void *value){

FILE *fPTR;
char buffer;
float number;

char *fileName ="data2.in";

fPTR = fopen(fileName,"r");

if (fPTR == NULL){

printf("was unable to open: %s\
", fileName);
return NULL;
}

while(1){

//Critical Section of Thread2
pthread_mutex_lock(&mutex1);
fscanf(fPTR,"%c%f\
", &buffer, &number);

if(buffer == '+'){

balance += number;

}
if(buffer == '-'){

balance -= number;
}

printf("Account balance of thread2 is: %f\
", balance);

if(feof(fPTR)){

fclose(fPTR);
printf("end of data2.in");
return NULL;
}

printf("end of while thread2\
");
pthread_mutex_unlock(&mutex1);

sleep(.3);
}

}

void *thread3(void *value){

FILE *fPTR;
char buffer;
float number;

char *fileName ="data3.in";

fPTR = fopen(fileName,"r");

if (fPTR == NULL){

printf("was unable to open: %s\
", fileName);
return NULL;
}

while(1){

//Critical Section of Thread3
pthread_mutex_lock(&mutex1);
fscanf(fPTR,"%c%f\
", &buffer, &number);

if(buffer == '+'){

balance += number;

}
if(buffer == '-'){

balance -= number;
}

printf("Account balance of thread3 is: %f\
", balance);

if(feof(fPTR)){

fclose(fPTR);
printf("end of data3.in");
return NULL;
}

printf("end of while thread3\
");
pthread_mutex_unlock(&mutex1);

sleep(.3);
}

}

void *thread4(void *value){

FILE *fPTR;
char buffer;
float number;

char *fileName ="data4.in";

fPTR = fopen(fileName,"r");

if (fPTR == NULL){

printf("was unable to open: %s\
", fileName);
return NULL;
}

while(1){

//Critical Section of Thread4
pthread_mutex_lock(&mutex1);
fscanf(fPTR,"%c%f\
", &buffer, &number);

if(buffer == '+'){

balance += number;

}
if(buffer == '-'){

balance -= number;
}

printf("Account balance of thread4 is: %f\
", balance);

if(feof(fPTR)){

fclose(fPTR);
printf("end of data4.in");
return NULL;
}

printf("end of while thread4\
");
pthread_mutex_unlock(&mutex1);

sleep(.3);
}

}

void *thread5(void *value){

FILE *fPTR;
char buffer;
float number;

char *fileName ="data5.in";

fPTR = fopen(fileName,"r");

if (fPTR == NULL){

printf("was unable to open: %s\
", fileName);
return NULL;
}

while(1){

//Critical Section of Thread5
pthread_mutex_lock(&mutex1);
fscanf(fPTR,"%c%f\
", &buffer, &number);

if(buffer == '+'){

balance += number;

}
if(buffer == '-'){

balance -= number;
}

printf("Account balance of thread5 is: %f\
", balance);

if(feof(fPTR)){

fclose(fPTR);
printf("end of data5.in");
return NULL;
}

printf("end of while thread5\
");
pthread_mutex_unlock(&mutex1);

sleep(.3);
}

}

int main(int argc, char **argv){

pthread_t pthread1;
pthread_t pthread2;
pthread_t pthread3;
pthread_t pthread4;
pthread_t pthread5;

pthread_create(&pthread1, NULL, thread1, NULL);
pthread_create(&pthread2, NULL, thread2, NULL);
pthread_create(&pthread3, NULL, thread3, NULL);
pthread_create(&pthread4, NULL, thread4, NULL);
pthread_create(&pthread5, NULL, thread5, NULL);

pthread_detach(pthread1);
pthread_detach(pthread2);
pthread_detach(pthread3);
pthread_detach(pthread4);
pthread_detach(pthread5);

printf("main completed\
");

pthread_exit(0);

}