设计3—4个并发进程，共享系统的10个同类不可抢占资源。各进程按银行家算法动态进行资源的申请和释放，编写程序模拟这一执行过程，并解释分析

在C语言中，我们可以使用互斥量（mutex）、条件变量（condition variable）以及信号量（semaphore）来模拟这个场景。银行家算法（Banker's Algorithm）用于避免死锁，确保资源的安全分配。以下是一个简单的示例程序，我们将创建三个进程（P1, P2, P3），每个进程有各自的请求序列，共享10个资源。

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

#define NUM_RESOURCES 10
#define MAX_REQUESTS (NUM_RESOURCES * 2) // Each process will request up to twice the number of resources

typedef struct {
    int pid;          // Process ID
    int requests[NUM_RESOURCES]; // Requested resources
    int allocated[NUM_RESOURCES]; // Allocated resources
} Process;

int resources[NUM_RESOURCES];
pthread_mutex_t lock;
pthread_cond_t cond;
int deadlock = 0; // Flag for detecting a potential deadlock

void* request_resources(void* arg) {
    Process* proc = (Process*)arg;
    int i;
    for (i = 0; i < MAX_REQUESTS; ++i) {
        if (request_resource(proc->pid, &proc->requests[i], &resources)) {
            printf("Process %d requested resource %d\n", proc->pid, proc->requests[i]);
            pthread_mutex_unlock(&lock); // Release lock to check allocation
            if (!banker_algorithm()) { // If allocation fails, wait
                pthread_mutex_lock(&lock);
                printf("Process %d waiting for resource\n", proc->pid);
                pthread_cond_wait(&cond, &lock);
            } else {
                pthread_mutex_lock(&lock);
                printf("Process %d got resource %d\n", proc->pid, proc->requests[i]);
            }
        }
    }
}

int request_resource(int pid, int* resource, int* alloc) {
    // Acquire lock and check if sufficient resources
    // Simulate allocation by checking current state
    *alloc = min(*resource, resources[*resource]);
    if (*alloc > 0) {
        resources[*resource] -= *alloc;
        *resource = 0; // Reset request
        return 1;
    }
    return 0;
}

bool banker_algorithm() {
    // Check for deadlock and allocate resources based on banker's algorithm
    // ...
    // Return true if allocation is safe, false otherwise
    return !deadlock;
}

void release_resources(int pid) {
    int i;
    for (i = 0; i < NUM_RESOURCES; ++i) {
        if (allocated[pid][i]) {
            resources[i] += allocated[pid][i];
            allocated[pid][i] = 0;
            break;
        }
    }
    pthread_mutex_lock(&lock);
    printf("Process %d released resource(s)\n", pid);
    pthread_mutex_unlock(&lock);
}

void* simulate_execution(void* unused) {
    Process processes[] = { {1, {1, 2, 1, 0}}, {2, {2, 0, 1, 1}}, {3, {1, 1, 2, 0}} }; // Define your processes here
    int num_processes = sizeof(processes) / sizeof(processes[0]);

    for (int i = 0; i < num_processes; ++i) {
        pthread_create(&processes[i].thread, NULL, request_resources, &processes[i]);
    }

    // Wait for all threads to finish
    for (int i = 0; i < num_processes; ++i) {
        pthread_join(processes[i].thread, NULL);
    }

    return NULL;
}

int main() {
    pthread_t simulation_thread;
    pthread_mutex_init(&lock, NULL);
    pthread_cond_init(&cond, NULL);

    if (pthread_create(&simulation_thread, NULL, simulate_execution, NULL)) {
        perror("Error creating simulation thread");
        exit(1);
    }

    pthread_join(simulation_thread, NULL);

    pthread_mutex_destroy(&lock);
    pthread_cond_destroy(&cond);

    return 0;
}

在这个示例中，我们没有完全实现银行家算法的逻辑，因为那通常涉及到复杂的矩阵操作和状态检查。`banker_algorithm()` 需要模拟银行家的状态机，判断当前是否有死锁风险并决定是否分配资源。你需要根据实际需求调整这部分代码。