Query and/or set the limit for Resource. Time-values are in
seconds and size-values are counted in bytes. The following values are
supported by this library. Please note that not all resources may be
available and accessible on all platforms. This predicate can throw a
variety of exceptions. In portable code this should be guarded with catch/3.
The defined resources are:
as | Max address space |
cpu | CPU time in seconds |
fsize | Maximum filesize |
data | max data size |
stack | max stack size |
core | max core file size |
rss | max resident set size |
nproc | max number of processes |
nofile | max number of open files |
memlock | max locked-in-memory address |
When the process hits a limit POSIX systems normally send the process
a signal that terminates it. These signals may be caught using
SWI-Prolog's on_signal/3
primitive. The code below illustrates this behaviour. Please note that
asynchronous signal handling is dangerous, especially when using
threads. 100% fail-safe operation cannot be guaranteed, but this
procedure will inform the user properly‘most of the time’.
rlimit_demo :-
rlimit(cpu, _, 2),
on_signal(xcpu, _, cpu_exceeded),
( repeat, fail ).
cpu_exceeded(_Sig) :-
format(user_error, 'CPU time exceeded~n', []),
halt(1).
