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support retrieving the sums of the self and child resource consumptions
simultaneously.

In list context getrusage() returns the current resource usages as a
list. On failure it returns an empty list.

The elements of the list are, in order:
	index	name		meaning usually (quite system dependent)

	 0	utime		user time
	 1	stime		system time
    	 2	maxrss		maximum shared memory or current resident set
	 3	ixrss		integral shared memory
	 4	idrss		integral or current unshared data
	 5	isrss		integral or current unshared stack
	 6	minflt		page reclaims
	 7	majflt		page faults
    	 8	nswap		swaps
	 9	inblock		block input operations
	10	oublock		block output operations
	11	msgsnd		messages sent
	12	msgrcv		messaged received
	13	nsignals	signals received
	14	nvcsw		voluntary context switches
	15	nivcsw		involuntary context switches

In scalar context getrusage() returns the current resource usages as a
an object. The object can be queried via methods named exactly like
the middle column, I<name>, in the above table.

	$ru = getrusage();
	print $ru->stime, "\n";

	$total_context_switches = $ru->nvcsw + $ru->nivcsw;

For a detailed description about the values returned by getrusage()
please consult your usual C programming documentation about
getrusage() and also the header file C<E<lt>sys/resource.hE<gt>>.
(In B<Solaris>, this might be C<E<lt>sys/rusage.hE<gt>>).

See also L</"KNOWN ISSUES">.

=head2 getrlimit

	($nowsoft, $nowhard) = getrlimit($resource);

	$rlimit = getrlimit($resource);

The $resource argument can be one of

        $resource               usual meaning           usual unit

        RLIMIT_CPU              CPU time                seconds

        RLIMIT_FSIZE            file size               bytes

        RLIMIT_DATA             data size               bytes
        RLIMIT_STACK            stack size              bytes
        RLIMIT_CORE             coredump size           bytes
        RLIMIT_RSS              resident set size       bytes
        RLIMIT_MEMLOCK          memory locked data size bytes

        RLIMIT_NPROC            number of processes     1

        RLIMIT_NOFILE           number of open files    1
        RLIMIT_OFILE            number of open files    1
        RLIMIT_OPEN_MAX         number of open files    1

        RLIMIT_LOCKS            number of file locks    1

        RLIMIT_AS               (virtual) address space bytes
        RLIMIT_VMEM             virtual memory (space)  bytes

        RLIMIT_PTHREAD          number of pthreads      1
        RLIMIT_TCACHE           maximum number of       1
                                cached threads

        RLIMIT_AIO_MEM          maximum memory locked   bytes
                                for POSIX AIO
        RLIMIT_AIO_OPS          maximum number          1
                                for POSIX AIO ops

        RLIMIT_FREEMEM          portion of the total memory

        RLIMIT_NTHR             maximum number of       1
                                threads

        RLIMIT_NPTS             maximum number of       1
                                pseudo-terminals

        RLIMIT_RSESTACK         RSE stack size          bytes

        RLIMIT_SBSIZE           socket buffer size      bytes

        RLIMIT_SWAP             maximum swap size       bytes

        RLIMIT_MSGQUEUE         POSIX mq size           bytes

        RLIMIT_RTPRIO           maximum RT priority     1
        RLIMIT_RTTIME           maximum RT time         microseconds
        RLIMIT_SIGPENDING       pending signals         1

B<What limits are available depends on the operating system>.

See below for C<get_rlimits()> on how to find out which limits are
available, for the exact documentation consult the documentation of
your operating system (setrlimit documentation, usually).

The two groups (C<NOFILE>, C<OFILE>, C<OPEN_MAX>) and (C<AS>, C<VMEM>)
are aliases within themselves.

Two meta-resource-symbols might exist

	RLIM_NLIMITS
	RLIM_INFINITY

C<RLIM_NLIMITS> being the number of possible (but not necessarily fully
supported) resource limits, see also the get_rlimits() call below.
C<RLIM_INFINITY> is useful in setrlimit(), the C<RLIM_INFINITY> is
often represented as minus one (-1).

In list context C<getrlimit()> returns the current soft and hard
resource limits as a list.  On failure it returns an empty list.

Processes have soft and hard resource limits.  On crossing the soft
limit they receive a signal (for example the C<SIGXCPU> or C<SIGXFSZ>,
corresponding to the C<RLIMIT_CPU> and C<RLIMIT_FSIZE>, respectively).
The processes can trap and handle some of these signals, please see
L<perlipc/Signals>.  After the hard limit the processes will be
ruthlessly killed by the C<KILL> signal which cannot be caught.

B<NOTE>: the level of 'support' for a resource varies. Not all the systems

	a) even recognise all those limits
	b) really track the consumption of a resource
	c) care (send those signals) if a resource limit is exceeded

Again, please consult your usual C programming documentation.