Creating a Thread [using clone() function]

The clone() function in C is a low-level system call that can be used to create a new thread in Linux-based systems. Unlike pthread_create(), which is part of the POSIX thread library and provides a higher-level interface for thread management, clone() gives you more control over the created thread.

An example of using clone() function to create a new thread

#define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <sched.h> #include <unistd.h> #include <sys/wait.h> #define STACK_SIZE (1024 * 1024) // Stack size for the cloned thread int threadFunction(void *arg) { printf("Hello from the cloned thread!\n"); return 0; } int main() { char *stack; // Stack for the cloned thread char *stackTop; // Top of the stack pid_t pid; // Allocate memory for the stack stack = malloc(STACK_SIZE); if (stack == NULL) { perror("malloc"); exit(EXIT_FAILURE); } // Set the top of the stack stackTop = stack + STACK_SIZE; // Create a new thread using clone pid = clone(threadFunction, stackTop, CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND, NULL); if (pid == -1) { perror("clone"); exit(EXIT_FAILURE); } // Wait for the cloned thread to terminate if (waitpid(pid, NULL, 0) == -1) { perror("waitpid"); exit(EXIT_FAILURE); } printf("Hello from the main thread!\n"); // Free the allocated stack memory free(stack); return 0; }

In this example, the clone() function is used to create a new thread that executes the threadFunction(). The CLONE_VM, CLONE_FS, CLONE_FILES, and CLONE_SIGHAND flags are used to share the memory space, file system information, file descriptors, and signal handlers between the parent and child threads.

Please note that using clone() directly is more complex and error-prone compared to pthread_create(). It requires careful handling of memory management, synchronization, and other aspects of multithreading. It's generally recommended to use pthread_create() unless you have specific requirements that necessitate the use of low-level functions like clone().

Happy Exploring!