https://nalar.dev/tags/process-identity/ Recent content in Process Identity on Nalar Hugo en-us Thu, 17 Sep 2026 00:00:00 +0000 https://nalar.dev/pidfds-turn-process-identity-into-a-stable-kernel-reference/ Thu, 17 Sep 2026 00:00:00 +0000 https://nalar.dev/pidfds-turn-process-identity-into-a-stable-kernel-reference/ <p>A supervisor records PID 1842 for a worker, waits for an asynchronous event, then sends a signal. Between those operations the worker can exit, be reaped, and its numeric PID can later identify another process. The number still looks valid, but the identity it denotes has changed.</p> <p>Linux pidfds move this class of process control away from repeated numeric lookup. A PID file descriptor refers to a particular process, giving userspace a kernel-held reference that can be passed to interfaces such as <code>pidfd_send_signal()</code>, polling APIs, and, under additional permission checks, <code>pidfd_getfd()</code>.</p>