Understanding Processes, Threads, and Synchronization in Operating Systems

The CPU is the core of a computer, acting like a factory that continuously executes tasks, while the operating system manages scheduling and resource allocation.

A program is static code, whereas a process is the dynamic execution instance of that program; multiple processes can run concurrently, each containing at least one thread.

Threads are lightweight execution units within a process, sharing the process's memory space, and are analogous to workers on an assembly line.

Synchronization primitives prevent conflicts: a mutex (Mutual Exclusion) ensures that only one thread accesses a critical section at a time, and a semaphore controls access to a limited pool of resources.

Processes transition through five states—initial, running, waiting, ready, and terminated—while threads have states: NEW, Runnable, Running, BLOCKED, and DEAD.

Inter‑process communication (IPC) includes pipes, message queues, semaphores, shared memory, and sockets. Pipes come in three forms: PIPE (ordinary pipe, often half‑duplex), s_pipe (stream pipe, bidirectional), and name_pipe (named pipe, usable between unrelated processes).

In the Java Memory Model (JMM), threads communicate via shared memory: a thread writes to main memory, and another reads from it, ensuring data consistency.

Synchronization mechanisms such as synchronized locks, explicit Lock objects, and atomic classes provide ordered and safe access to shared data.

Single‑CPU systems achieve concurrency through multithreading, while multi‑CPU systems enable true parallel execution of multiple threads.

Overall, modern operating systems execute tasks using multiple processes and threads, offering coordination mechanisms that allow shared resources while preventing interference.