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Commit 56dfc1e6 authored by Fred Drake's avatar Fred Drake
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Some reorganization (all limit operations & constants together, and all usage 

functions and constants together).

Make explicit datadesc sections for each of the constants which might appear,
and have a description of each.  (Descriptions are based on the Linux
documentation and sources and the Solaris man pages.)

Hopefully Jeremy won't mind, because I didn't ask.  ;-)
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Doc/lib/libresource.tex
View file @ 56dfc1e6
......@@ -7,64 +7,134 @@ 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.
children.
Resources usage can be limited using the \code{setrlimit} function
A single exception is defined for errors:
\renewcommand{\indexsubitem}{(in module resource)}
\begin{excdesc}{error}
The functions described below may raise this error if the underlying
system call failures unexpectedly.
\end{excdesc}
\subsection{Resource Limits}
Resources usage can be limited using the \code{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 process with
the effective UID of the super-user can raise a hard limit).
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 \code{getrlimit} man page. Typical resources
include:
are described in the \code{getrlimit()} 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.
\begin{description}
\begin{funcdesc}{getrlimit}{resource}
Returns a tuple \code{(\var{soft}, \var{hard})} with the current
soft and hard limits of \var{resource}. Raises \code{ValueError} if
an invalid resource is specified, or \code{resource.error} if the
underyling system call fails unexpectedly.
\end{funcdesc}
\item[RLIMIT_CORE]
The maximum size (in bytes) of a core file that the current process
can create.
\begin{funcdesc}{setrlimit}{resource, limits}
Sets new limits of consumption of \var{resource}. The \var{limits}
argument must be a tuple \code{(\var{soft}, \var{hard})} of two
integers describing the new limits. A value of \code{-1} can be used to
specify the maximum possible upper limit.
\item[RLIMIT_CPU]
The maximum amount of CPU time (in seconds) that a process can use. If
this limit is exceeded, a \code{SIGXCPU} signal is sent to the
process. (See the \code{signal} module documentation for information
about how to catch this signal and do something useful, e.g. flush
open files to disk.)
Raises \code{ValueError} if an invalid resource is specified, if the new
soft limit exceeds the hard limit, or if a process tries to raise its
hard limit (unless the process has an effective UID of
super-user). Can also raise a \code{resource.error} if the
underyling system call fails.
\end{funcdesc}
\end{description}
These symbols define resources whose consumption can be controlled
using the \code{setrlimit()} and \code{getrlimit()} functions defined
below. The values of these symbols are exactly the constants used
by C programs.
\begin{datadesc}{RLIMIT_*}
These symbols define resources whose consumption can be controlled
using the \code{setrlimit} and \code{getrlimit} functions defined
below. The values of these symbols are exactly the constants used
by C programs.
The \UNIX{} man page for \code{getrlimit()} lists the available
resources. Note that not all systems use the same symbol or same
value to denote the same resource.
The \UNIX{} man page for \file{getrlimit} lists the available
resources. Note that not all systems use the same symbol or same
value to denote the same resource.
\begin{datadesc}{RLIMIT_CORE}
The maximum size (in bytes) of a core file that the current process
can create. This may result in the creation of a partial core file
if a larger core would be required to contain the entire process
image.
\end{datadesc}
\begin{datadesc}{RUSAGE_*}
These symbols are passed to the \code{getrusage} function to specify
whether usage information is being request for the current process,
\code{RUSAGE_SELF} or its child processes \code{RUSAGE_CHILDREN}. On
some system, \code{RUSAGE_BOTH} requests information for both.
\begin{datadesc}{RLIMIT_CPU}
The maximum amount of CPU time (in seconds) that a process can
use. If this limit is exceeded, a \code{SIGXCPU} signal is sent to
the process. (See the \code{signal} module documentation for
information about how to catch this signal and do something useful,
e.g. flush open files to disk.)
\end{datadesc}
\begin{datadesc}{error}
The functions described below may raise this error if the underlying
system call failures unexpectedly.
\begin{datadesc}{RLIMIT_FSIZE}
The maximum size of a file which the process may create. This only
affects the stack of the main thread in a multi-threaded process.
\end{datadesc}
\begin{datadesc}{RLIMIT_DATA}
The maximum size (in bytes) of the process's heap.
\end{datadesc}
\begin{datadesc}{RLIMIT_STACK}
The maximum size (in bytes) of the call stack for the current
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_RSS}
The maximum resident set size that should be made available to the
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_NPROC}
The maximum number of processes the current process may create.
\end{datadesc}
The resource module defines the following functions:
\begin{datadesc}{RLIMIT_NOFILE}
The maximum number of open file descriptors for the current
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_OFILE}
The BSD name for \code{RLIMIT_NOFILE}.
\end{datadesc}
\begin{datadesc}{RLIMIT_MEMLOC}
The maximm address space which may be locked in memory.
\end{datadesc}
\begin{datadesc}{RLIMIT_VMEM}
The largest area of mapped memory which the process may occupy.
\end{datadesc}
\begin{datadesc}{RLIMIT_AS}
The maximum area (in bytes) of address space which may be taken by
the process.
\end{datadesc}
\subsection{Resource Usage}
These functiona are used to retrieve resource usage information:
\begin{funcdesc}{getrusage}{who}
This function returns a large tuple that describes the resources
consumed by either the current process or its children, as specified
by the \var{who} parameter. The elements of the return value each
by the \var{who} parameter. The \var{who} parameter should be
specified using one of the \code{RUSAGE_}* constants described
below.
The elements of the return value each
describe how a particular system resource has been used, e.g. amount
of time spent running is user mode or number of times the process was
swapped out of main memory. Some values are dependent on the clock
......@@ -73,7 +143,7 @@ The resource module defines the following functions:
The first two elements of the return value are floating point values
representing the amount of time spent executing in user mode and the
amount of time spent executing in system mode, respectively. The
remaining values are integers. Consult the \code{getrusage} man page
remaining values are integers. Consult the \code{getrusage()} man page
for detailed information about these values. A brief summary is
presented here:
......@@ -97,7 +167,7 @@ The resource module defines the following functions:
15 & involuntary context switches \\
\end{tabular}
This function will raise a ValueError if an invalid \var{who}
This function will raise a \code{ValueError} if an invalid \var{who}
parameter is specified. It may also raise a \code{resource.error}
exception in unusual circumstances.
\end{funcdesc}
......@@ -111,22 +181,22 @@ The resource module defines the following functions:
bytes.
\end{funcdesc}
\begin{funcdesc}{getrlimit}{resource}
Returns a tuple \code{(\var{soft}, \var{hard})} with the current
soft and hard limits of \var{resource}. Raises ValueError if
an invalid resource is specified, or \code{resource.error} if the
underyling system call fails unexpectedly.
\end{funcdesc}
The following \code{RUSAGE_}* symbols are passed to the
\code{getrusage()} function to specify which processes information
should be provided for.
\begin{funcdesc}{setrlimit}{resource\, limits}
Sets new limits of consumption of \var{resource}. The \var{limits}
argument must be a tuple \code{(\var{soft}, \var{hard})} of two
integers describing the new limits. A value of -1 can be used to
specify the maximum possible upper limit.
\begin{datadesc}{RUSAGE_SELF}
\code{RUSAGE_SELF} should be used to
request information pertaining only to the process itself.
\end{datadesc}
Raises ValueError if an invalid resource is specified, if the new
soft limit exceeds the hard limit, or if a process tries to raise its
hard limit (unless the process has an effective UID of
super-user). Can also raise a \code{resource.error} if the
underyling system call fails.
\end{funcdesc}
\begin{datadesc}{RUSAGE_CHILDREN}
Pass to \code{getrusage()} to request resource information for child
processes of the calling process.
\end{datadesc}
\begin{datadesc}{RUSAGE_BOTH}
Pass to \code{getrusage()} to request resources consumed by both the
current process and child processes. May not be available on all
systems.
\end{datadesc}
Doc/libresource.tex
View file @ 56dfc1e6
......@@ -7,64 +7,134 @@ 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.
children.
Resources usage can be limited using the \code{setrlimit} function
A single exception is defined for errors:
\renewcommand{\indexsubitem}{(in module resource)}
\begin{excdesc}{error}
The functions described below may raise this error if the underlying
system call failures unexpectedly.
\end{excdesc}
\subsection{Resource Limits}
Resources usage can be limited using the \code{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 process with
the effective UID of the super-user can raise a hard limit).
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 \code{getrlimit} man page. Typical resources
include:
are described in the \code{getrlimit()} 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.
\begin{description}
\begin{funcdesc}{getrlimit}{resource}
Returns a tuple \code{(\var{soft}, \var{hard})} with the current
soft and hard limits of \var{resource}. Raises \code{ValueError} if
an invalid resource is specified, or \code{resource.error} if the
underyling system call fails unexpectedly.
\end{funcdesc}
\item[RLIMIT_CORE]
The maximum size (in bytes) of a core file that the current process
can create.
\begin{funcdesc}{setrlimit}{resource, limits}
Sets new limits of consumption of \var{resource}. The \var{limits}
argument must be a tuple \code{(\var{soft}, \var{hard})} of two
integers describing the new limits. A value of \code{-1} can be used to
specify the maximum possible upper limit.
\item[RLIMIT_CPU]
The maximum amount of CPU time (in seconds) that a process can use. If
this limit is exceeded, a \code{SIGXCPU} signal is sent to the
process. (See the \code{signal} module documentation for information
about how to catch this signal and do something useful, e.g. flush
open files to disk.)
Raises \code{ValueError} if an invalid resource is specified, if the new
soft limit exceeds the hard limit, or if a process tries to raise its
hard limit (unless the process has an effective UID of
super-user). Can also raise a \code{resource.error} if the
underyling system call fails.
\end{funcdesc}
\end{description}
These symbols define resources whose consumption can be controlled
using the \code{setrlimit()} and \code{getrlimit()} functions defined
below. The values of these symbols are exactly the constants used
by C programs.
\begin{datadesc}{RLIMIT_*}
These symbols define resources whose consumption can be controlled
using the \code{setrlimit} and \code{getrlimit} functions defined
below. The values of these symbols are exactly the constants used
by C programs.
The \UNIX{} man page for \code{getrlimit()} lists the available
resources. Note that not all systems use the same symbol or same
value to denote the same resource.
The \UNIX{} man page for \file{getrlimit} lists the available
resources. Note that not all systems use the same symbol or same
value to denote the same resource.
\begin{datadesc}{RLIMIT_CORE}
The maximum size (in bytes) of a core file that the current process
can create. This may result in the creation of a partial core file
if a larger core would be required to contain the entire process
image.
\end{datadesc}
\begin{datadesc}{RUSAGE_*}
These symbols are passed to the \code{getrusage} function to specify
whether usage information is being request for the current process,
\code{RUSAGE_SELF} or its child processes \code{RUSAGE_CHILDREN}. On
some system, \code{RUSAGE_BOTH} requests information for both.
\begin{datadesc}{RLIMIT_CPU}
The maximum amount of CPU time (in seconds) that a process can
use. If this limit is exceeded, a \code{SIGXCPU} signal is sent to
the process. (See the \code{signal} module documentation for
information about how to catch this signal and do something useful,
e.g. flush open files to disk.)
\end{datadesc}
\begin{datadesc}{error}
The functions described below may raise this error if the underlying
system call failures unexpectedly.
\begin{datadesc}{RLIMIT_FSIZE}
The maximum size of a file which the process may create. This only
affects the stack of the main thread in a multi-threaded process.
\end{datadesc}
\begin{datadesc}{RLIMIT_DATA}
The maximum size (in bytes) of the process's heap.
\end{datadesc}
\begin{datadesc}{RLIMIT_STACK}
The maximum size (in bytes) of the call stack for the current
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_RSS}
The maximum resident set size that should be made available to the
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_NPROC}
The maximum number of processes the current process may create.
\end{datadesc}
The resource module defines the following functions:
\begin{datadesc}{RLIMIT_NOFILE}
The maximum number of open file descriptors for the current
process.
\end{datadesc}
\begin{datadesc}{RLIMIT_OFILE}
The BSD name for \code{RLIMIT_NOFILE}.
\end{datadesc}
\begin{datadesc}{RLIMIT_MEMLOC}
The maximm address space which may be locked in memory.
\end{datadesc}
\begin{datadesc}{RLIMIT_VMEM}
The largest area of mapped memory which the process may occupy.
\end{datadesc}
\begin{datadesc}{RLIMIT_AS}
The maximum area (in bytes) of address space which may be taken by
the process.
\end{datadesc}
\subsection{Resource Usage}
These functiona are used to retrieve resource usage information:
\begin{funcdesc}{getrusage}{who}
This function returns a large tuple that describes the resources
consumed by either the current process or its children, as specified
by the \var{who} parameter. The elements of the return value each
by the \var{who} parameter. The \var{who} parameter should be
specified using one of the \code{RUSAGE_}* constants described
below.
The elements of the return value each
describe how a particular system resource has been used, e.g. amount
of time spent running is user mode or number of times the process was
swapped out of main memory. Some values are dependent on the clock
......@@ -73,7 +143,7 @@ The resource module defines the following functions:
The first two elements of the return value are floating point values
representing the amount of time spent executing in user mode and the
amount of time spent executing in system mode, respectively. The
remaining values are integers. Consult the \code{getrusage} man page
remaining values are integers. Consult the \code{getrusage()} man page
for detailed information about these values. A brief summary is
presented here:
......@@ -97,7 +167,7 @@ The resource module defines the following functions:
15 & involuntary context switches \\
\end{tabular}
This function will raise a ValueError if an invalid \var{who}
This function will raise a \code{ValueError} if an invalid \var{who}
parameter is specified. It may also raise a \code{resource.error}
exception in unusual circumstances.
\end{funcdesc}
......@@ -111,22 +181,22 @@ The resource module defines the following functions:
bytes.
\end{funcdesc}
\begin{funcdesc}{getrlimit}{resource}
Returns a tuple \code{(\var{soft}, \var{hard})} with the current
soft and hard limits of \var{resource}. Raises ValueError if
an invalid resource is specified, or \code{resource.error} if the
underyling system call fails unexpectedly.
\end{funcdesc}
The following \code{RUSAGE_}* symbols are passed to the
\code{getrusage()} function to specify which processes information
should be provided for.
\begin{funcdesc}{setrlimit}{resource\, limits}
Sets new limits of consumption of \var{resource}. The \var{limits}
argument must be a tuple \code{(\var{soft}, \var{hard})} of two
integers describing the new limits. A value of -1 can be used to
specify the maximum possible upper limit.
\begin{datadesc}{RUSAGE_SELF}
\code{RUSAGE_SELF} should be used to
request information pertaining only to the process itself.
\end{datadesc}
Raises ValueError if an invalid resource is specified, if the new
soft limit exceeds the hard limit, or if a process tries to raise its
hard limit (unless the process has an effective UID of
super-user). Can also raise a \code{resource.error} if the
underyling system call fails.
\end{funcdesc}
\begin{datadesc}{RUSAGE_CHILDREN}
Pass to \code{getrusage()} to request resource information for child
processes of the calling process.
\end{datadesc}
\begin{datadesc}{RUSAGE_BOTH}
Pass to \code{getrusage()} to request resources consumed by both the
current process and child processes. May not be available on all
systems.
\end{datadesc}
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