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|Limiting process resources|
library(rlimit) library provides an interface to the
POSIX getrlimit()/setrlimit() API that control the maximum
resource-usage of a process or group of processes. This call is
especially useful for servers such as CGI scripts and inetd-controlled
servers to avoid an uncontrolled script claiming too much resources.
Max address space
CPU time in seconds
max data size
max stack size
max core file size
max resident set size
max number of processes
max number of open files
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).