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Concurrent Collatz Conjecture with Multiple Processes in C

This C program explores the Collatz conjecture concurrently using multiple processes. It begins by validating a command-line argument as the initial number for the conjecture. If successful, two child processes are spawned to independently execute the conjecture. The parent process waits for both children to complete before concluding the program. The Collatz conjecture steps are detailed for each process, displaying the evolution of the sequence. This implementation not only demonstrates the classic mathematical problem but also illustrates the parallel execution of the conjecture, showcasing the use of fork() for process creation in a multi-process environment.

Parallel Collatz Conjecture: Concurrent Exploration in C

This C program showcases the parallel execution of the Collatz conjecture using multiple processes, demonstrating a practical application of concurrent programming. The code begins by validating a user-provided initial number for the conjecture, offering clarity on proper usage. By leveraging fork() for process creation, two child processes independently execute the Collatz sequence, providing a clear illustration of parallel computation. The parent process efficiently manages the synchronization of the child processes through wait(). This code not only serves as a valuable educational resource for understanding parallel programming in C but can also act as a helpful reference for students seeking assistance with their C assignments in concurrent computing.

Block 1: Header Files

#include < stdio.h > #include < stdlib.h > #include < sys/wait.h > #include < unistd.h >

These are the standard C libraries being included:

  • < stdio.h >: Input and output functions.
  • < stdlib.h >: General-purpose standard library functions (e.g., atoi for string to integer conversion).
  • < sys/wait.h >: Defines the wait function for process synchronization.
  • < unistd.h >: Declares functions like fork and getpid for process-related operations.

Block 2: Function Definition – doCollatz

void doCollatz(int processId, int childNumber, int number) { // Function body }

This block defines a function named doCollatz that takes three parameters (processId, childNumber, and number). This function implements the Collatz conjecture, printing sequences of numbers until a certain condition is met.

Block 3: Main Function

int main(int argc, char *argv[]) { // Function body }

This block checks whether the correct number of command line arguments is provided. If not, it prints a usage message and exits the program.

Block 4: Command Line Argument Check

if (argc != 2) { printf("Usage: %s \n", argv[0]); return 0; }

This block checks whether the correct number of command line arguments is provided. If not, it prints a usage message and exits the program.

Block 5: Convert Argument to Integer

int collatzNumber = atoi(argv[1]);

This converts the command line argument (assumed to be the Collatz number) from string to an integer using the atoi function.

Block 6: Range Check for Collatz Number

if (collatzNumber <= 0 || collatzNumber >= 40) { printf("The collatz number should be a value between 1 and 39 inclusive.\n"); return 0; }

Ensures that the collatzNumber is within a valid range (1 to 39 inclusive). If not, it prints an error message and exits the program.

Block 7: Forking the First Child

pid_t processId1 = fork();

Forks the process into two: the parent process and the first child process. processId1 is used to determine whether the current process is the parent or the child.

Block 8: Parent Process (First Child)

if (processId1 > 0) { // We are in the parent process, fork the second child pid_t processId2 = fork(); // ... }

If processId1 is positive, the process is the parent. It then forks again to create the second child (processId2). The parent will wait for both children to finish.

Block 9: Second Child Process

if (processId2 > 0) { // We are in the parent process wait for children to finish printf("This is the Parent waiting!\n"); int status; wait(&status); wait(&status); printf("All my Children Complete\n"); } else { // We are in the second child process doCollatz(getpid(), 2, collatzNumber + 4); }

If processId2 is positive, this is still the parent. It waits for both children to finish and prints a completion message. If processId2 is not positive, it means this is the second child, and it calls the doCollatz function with appropriate arguments.

Block 10: First Child Process

} else { // We are in the first child process doCollatz(getpid(), 1, collatzNumber); }

If processId1 is not positive, it means this is the first child. It calls the doCollatz function with appropriate arguments.

Block 11: Program Completion

return 0;

This line signifies the end of the main function and returns 0 to the operating system, indicating successful program execution.


In conclusion, delving into the intricacies of concurrent programming in C with the Collatz conjecture exemplifies the fascinating realm of parallel computation. This exploration unveils the orchestration of parent and child processes, showcasing the power of forked executions. Through the lens of this program, developers gain insights into synchronization, process dynamics, and the essence of parallelism. As the blog demystifies the complexities, it empowers readers to embrace the elegance of concurrent C programming. Whether you're a seasoned programmer or a curious learner, this journey through forking processes illuminates the path toward mastering the art of concurrency in C, paving the way for more robust and efficient software solutions.