End of Life Ruby 3.2 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →
class method
Etc.nprocessors
nprocessors
ext/etc/etc.c
View on GitHub ↗
static VALUE
etc_nprocessors(VALUE obj)
{
long ret;
#if !defined(_WIN32)
#if defined(HAVE_SCHED_GETAFFINITY) && defined(CPU_ALLOC)
int ncpus;
ncpus = etc_nprocessors_affin();
if (ncpus != -1) {
return INT2NUM(ncpus);
}
/* fallback to _SC_NPROCESSORS_ONLN */
#endif
errno = 0;
ret = sysconf(_SC_NPROCESSORS_ONLN);
if (ret == -1) {
rb_sys_fail("sysconf(_SC_NPROCESSORS_ONLN)");
}
#else
SYSTEM_INFO si;
GetSystemInfo(&si);
ret = (long)si.dwNumberOfProcessors;
#endif
return LONG2NUM(ret);
}
Returns the number of online processors.
The result is intended as the number of processes to use all available processors.
This method is implemented using:
-
sched_getaffinity(): Linux
-
sysconf(_SC_NPROCESSORS_ONLN): GNU/Linux, NetBSD, FreeBSD, OpenBSD, DragonFly BSD, OpenIndiana, Mac OS X, AIX
Example:
Example
require 'etc' p Etc.nprocessors #=> 4
The result might be smaller number than physical cpus especially when ruby process is bound to specific cpus. This is intended for getting better parallel processing.
Example: (Linux)
linux$ taskset 0x3 ./ruby -retc -e "p Etc.nprocessors" #=> 2