psutilProcesspid

psutil.Process(pid) is a class in the psutil library that represents a system process identified by its process ID (pid). The pid must be a positive integer. A Process object provides access to the process’s metadata, status, and resource usage, and it also exposes methods to control the process or wait for it to finish.

Common information exposed through a Process object includes name(), exe(), cmdline(), status(), and ppid(). The object also exposes properties such as pid and is_running, and can produce structured summaries with as_dict() for selected fields. Resource usage is accessible via cpu_times(), cpu_percent(interval), memory_info() (and memory_full_info()), and io_counters(). The memory_info() result typically contains fields like rss (resident set size) and vms (virtual memory size). Other introspection methods include open_files(), connections(), threads(), and children() to explore related processes.

Process control and lifecycle methods enable management of the target process. terminate() sends a polite termination signal, while kill() forces immediate termination. suspend() and resume() pause and resume execution where supported. wait(timeout) can block until the process exits or the timeout elapses. The interface also supports inspecting and manipulating child processes and their resources.

Error handling and permissions are important considerations. Operations may raise psutil.NoSuchProcess if the process no longer exists, psutil.AccessDenied if the operating system denies access, or psutil.ZombieProcess for defunct processes. It is common to check p.is_running() and wrap calls in try/except blocks when working with arbitrary PIDs.

Cross-platform notes: psutil aims to provide a consistent API across major operating systems, but some fields, behaviors, or permissions vary between Linux, Windows, and macOS. Certain actions may require elevated privileges, and some information may be unavailable on specific platforms.