Question Type: This question tests knowledge of process management in operating systems, specifically focusing on the use of system calls for creating and managing processes.
Step-by-Step Logic:
- fork(): The
fork()system call is used to create a new process, which is a copy of the parent process. After a successfulfork(), the parent and child processes both continue execution from the point of thefork()call. - join(): The
join()system call (or a similar mechanism depending on the operating system) allows a parent process to wait for the termination of a child process before continuing its own execution. This ensures that the parent process doesn't proceed until the child process completes its task. - Complete Process Subroutine: A complete process subroutine implies that a parent process initiates a child process (using
fork()) to perform a specific task, and the parent process waits for the child process to finish before continuing (usingjoin()or an equivalent). This is a fundamental pattern in concurrent programming to ensure proper synchronization and order of execution.
Core Logic/Pattern: The core logic lies in the understanding of how fork() creates a new process and how join() synchronizes the parent and child process executions. They are used together to build complete process subroutines.
Eliminate Incorrect Options:
- Option 2 (fork(), sleep()):
sleep()pauses the execution of a process for a specified time. It doesn't coordinate the completion of a child process. - Option 3 (sleep(), join()):
sleep()alone doesn't initiate a child process.join()needs a process to wait for. - Option 4 (join(), fork()): The order is incorrect. You need to create the child process (
fork()) *before* waiting for its completion (join()).
Correct Answer: Option 1 (fork(), join()) is correct because it demonstrates the standard pattern for creating and synchronizing the execution of a child process within a parent process subroutine.
Important Questions from Process
A computer system has 7 tape drives. There are ‘n’ processes competing for them. Each process may need 2 tape drives. What is the maximum value of ‘n’ for which the system is guaranteed to be deadlock free?
Identify the circumstances under which pre-emptive CPU scheduling is used:
(a) A process switches from Running state to Ready state
(b) A process switches from Waiting state to Ready state
(c) A process completes its execution
(d) A process switches from Ready to Waiting state
Choose the correct option:
Match List I with List II
List I
List II
System calls
Description
A.
fork()
I.
Sends a signal from one process to another process
B.
exec()
II.
Indicates termination of the current process
C.
kill()
III.
Loads the specified program in the memory
D.
exit()
IV.
Creates a child process
Choose the correct answer from the options given below :
Assuming that the system call fork () never fails, consider the following C programs P1 and P2 executed on a UNIX / Linux system:
/*P1*/
Int main() {
fork ():
fork () ;
fork () ;
Printf(“Happy\n”);
}
/*P2*/
Int main() {
fork ();
Printf(“Happy\n”);
fork ()
Printf(“Happy\n”);
fork () ;
Printf(“Happy\n”);
}
Statement I: P1 displays "Happy" 8 times.
Statement II: P2 displays "Happy" 12 times.
In the light of the above statements, choose the correct answer from the options given below
________ system call creates new process in Unix.
