Topic in Operating Systems
A process is a program in execution, consisting of its code, program counter, registers, stack, heap and data, tracked by the kernel in a process control block. MCQs usually ask about the five-state model (new, ready, running, waiting, terminated) and which events trigger each transition. You should know what a context switch saves and why it is pure overhead, and how the long-term, short-term and medium-term schedulers differ. UNIX process creation is a frequent target: fork() return values, exec() replacing the address space, wait() and exit(), zombie and orphan processes, and copy-on-write. Interprocess communication through shared memory, pipes and message passing also appears regularly.
Below are 30 practice questions from a pool of 210 Process Management MCQs, one of 12 topics in Operating Systems. Each shows the correct answer with an explanation; when you are ready, take a timed quiz to test recall under exam conditions.
Each question below shows the correct answer with a full explanation. Use these to build conceptual understanding before attempting a timed quiz.
Q1. A process is:
A process is a program in execution. It includes the program code, current activity (program counter), stack, data section, and heap.
Q2. Which of the following is NOT a state of a process?
The standard process states are: New, Ready, Running, Waiting (Blocked), and Terminated. Compiling is not a process state.
Q3. The Process Control Block (PCB) contains:
The PCB contains all information about a process: process state, program counter, CPU registers, memory management info, I/O status, and accounting information.
Q4. What system call creates a new process in UNIX/Linux?
The fork() system call creates a new child process in UNIX/Linux. The child is a copy of the parent process.
Q5. A context switch occurs when:
A context switch occurs when the CPU switches from executing one process to another, saving the state of the old process and loading the state of the new one.
Q6. An orphan process is:
An orphan process is a child process that continues to run after its parent process has terminated. In UNIX, orphan processes are adopted by the init process.
Q7. A zombie process is:
A zombie process is one that has finished execution but still has an entry in the process table because its parent has not yet called wait() to read its exit status.
Q8. The program counter in a process stores:
The program counter (PC) holds the address of the next instruction to be executed for that process. It is saved and restored during context switches.
Q9. Inter-process communication (IPC) allows:
IPC mechanisms allow processes to communicate with each other and synchronize their actions. Common IPC methods include shared memory and message passing.
Q10. When a fork() system call is executed successfully, what does it return to the child process?
fork() returns 0 to the child process and the child's PID to the parent process. A return value of -1 indicates an error.
Q11. In the producer-consumer problem using shared memory, what role does the buffer play?
The buffer is a shared memory region where the producer places data items and the consumer removes them. It can be bounded (fixed size) or unbounded (theoretically unlimited).
Q12. What is the difference between shared memory and message passing IPC?
Shared memory uses a common memory region accessed by both processes (faster for large data). Message passing exchanges messages through the kernel and is easier to implement across different machines.
Q13. What happens during a context switch?
During a context switch, the OS saves the state (registers, program counter, etc.) of the currently running process to its PCB and loads the saved state of the next process to be executed.
Q14. In UNIX, what does the exec() family of system calls do?
The exec() family of system calls replaces the current process image with a new program. After exec(), the new program runs in the same process space with the same PID.
Q15. What is cascading termination?
Cascading termination is when the OS terminates all descendant processes of a parent when the parent terminates, since children cannot exist without their parent in some OS implementations.
Q16. A pipe in UNIX provides:
An ordinary (anonymous) pipe in UNIX provides unidirectional communication. It typically requires a parent-child relationship between processes. For bidirectional communication, two pipes are needed.
Q17. What is a named pipe (FIFO) and how does it differ from an ordinary pipe?
A named pipe (FIFO) exists as a file in the file system and can be used for communication between unrelated processes, unlike ordinary pipes which require a parent-child relationship.
Q18. Which scheduling queue holds processes that are in main memory and ready to execute?
The ready queue contains all processes residing in main memory that are ready and waiting to be assigned to the CPU for execution.
Q19. The long-term scheduler (job scheduler) controls:
The long-term scheduler controls which processes are admitted from the job pool to the ready queue, thus controlling the degree of multiprogramming in the system.
Q20. What is the role of the short-term scheduler (CPU scheduler)?
The short-term scheduler selects from among the processes in the ready queue and allocates the CPU to one of them. It runs very frequently (e.g., every 100 milliseconds).
Q21. In Chrome's multi-process architecture, what types of processes does it use?
Chrome uses a multi-process architecture with a browser process (managing UI and I/O), renderer processes (one per website for rendering), and plug-in processes (one per plug-in type) for isolation and stability.
Q22. What is the difference between direct and indirect communication in message passing?
In direct communication, processes explicitly name each other (send(P, msg)). In indirect communication, messages are sent to and received from mailboxes/ports, allowing multiple processes to share a mailbox.
Q23. What is the rendezvous mechanism in synchronous message passing?
In the rendezvous mechanism, both the sender blocks until the receiver receives the message, and the receiver blocks until a message is available. This ensures synchronized communication between processes.
Q24. In UNIX, how does the init process (PID 1) handle orphan processes?
When a parent terminates, its orphan children are adopted by the init process (PID 1). Init periodically calls wait() to collect exit statuses of these adopted processes, preventing zombie accumulation.
Q25. What is a socket in the context of IPC?
A socket is an endpoint for communication, defined by concatenating an IP address with a port number. Sockets enable communication between processes on different machines over a network.
Q26. What is Remote Procedure Call (RPC) in the context of distributed process communication?
RPC allows a process to call a procedure on a remote machine as if it were a local call. It uses stubs on client and server sides to handle the communication details transparently.
Q27. What is the purpose of the medium-term scheduler?
The medium-term scheduler performs swapping - moving processes between main memory and disk. It can reduce the degree of multiprogramming by swapping out processes and later swapping them back in.
Q28. In Android, what is a Binder and what role does it play?
Android's Binder is a high-performance IPC framework that provides RPC-like functionality using shared memory as the underlying transport mechanism for efficient cross-process communication.
Q29. What is the copy-on-write (COW) optimization used with fork()?
Copy-on-write allows the parent and child to initially share the same pages in memory. A page is copied only when either process tries to modify it, saving memory and improving fork() performance.
Q30. What is the purpose of the vfork() system call?
vfork() creates a child process that shares the parent's address space (no copy, not even COW). The parent is suspended until the child calls exec() or exit(), making it efficient when the child will immediately exec().
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