T36 Dec 19, 2025 2 min read

Process lifecycle

The stages a process moves through from creation to termination, including start, running, signals, and exit.

Definition

A process lifecycle is the sequence of states and events a process goes through: it starts, runs, may be interrupted by signals, and eventually terminates (cleanly or not).

A practical view of the lifecycle

Most applications experience the lifecycle as:

  1. process start: the OS creates the process and begins execution.
  2. Running: the process executes code and performs I/O.
  3. Interruption: the process may receive a signal (shutdown request, interrupt, etc.).
  4. Termination: the process exits with an exit code, or it ends via a crash / forced termination.

Why it matters

In production, many questions reduce to lifecycle questions:

  • Did the process start successfully?
  • Did it exit, and with what exit code?
  • Was it terminated by a signal (graceful vs forced)?
  • Did it crash (unexpected termination)?

Being precise about the lifecycle makes incidents less mysterious and speeds up debugging.