# :mod:resource --- Resource usage information

This module provides basic mechanisms for measuring and controlling system resources utilized by a program.

Symbolic constants are used to specify particular system resources and to request usage information about either the current process or its children.

An :exc:OSError is raised on syscall failure.

## Resource Limits

Resources usage can be limited using the :func:setrlimit function described below. Each resource is controlled by a pair of limits: a soft limit and a hard limit. The soft limit is the current limit, and may be lowered or raised by a process over time. The soft limit can never exceed the hard limit. The hard limit can be lowered to any value greater than the soft limit, but not raised. (Only processes with the effective UID of the super-user can raise a hard limit.)

The specific resources that can be limited are system dependent. They are described in the :manpage:getrlimit(2) man page. The resources listed below are supported when the underlying operating system supports them; resources which cannot be checked or controlled by the operating system are not defined in this module for those platforms.

These symbols define resources whose consumption can be controlled using the :func:setrlimit and :func:getrlimit functions described below. The values of these symbols are exactly the constants used by C programs.

The Unix man page for :manpage:getrlimit(2) lists the available resources. Note that not all systems use the same symbol or same value to denote the same resource. This module does not attempt to mask platform differences --- symbols not defined for a platform will not be available from this module on that platform.

## Resource Usage

These functions are used to retrieve resource usage information:

The following :const:RUSAGE_\* symbols are passed to the :func:getrusage function to specify which processes information should be provided for.