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.\" ========================================================================
.\"
.IX Title "MCE::Util 3pm"
.TH MCE::Util 3pm "2023-09-29" "perl v5.36.0" "User Contributed Perl Documentation"
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.SH "NAME"
MCE::Util \- Utility functions
.SH "VERSION"
.IX Header "VERSION"
This document describes MCE::Util version 1.889
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& use MCE::Util;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A utility module for \s-1MCE.\s0 Nothing is exported by default. Exportable is
get_ncpu.
.SS "\fBget_ncpu()\fP"
.IX Subsection "get_ncpu()"
Returns the number of logical (online/active/enabled) \s-1CPU\s0 cores; never smaller
than one.
.PP
.Vb 1
\& my $ncpu = MCE::Util::get_ncpu();
.Ve
.PP
Specifying 'auto' for max_workers calls MCE::Util::get_ncpu automatically.
\&\s-1MCE 1.521\s0 sets an upper-limit when specifying 'auto'. The reason is mainly
to safeguard apps from spawning 100 workers on a box having 100 cores.
This is important for apps which are IO-bound.
.PP
.Vb 1
\& use MCE;
\&
\& ## \*(AqAuto\*(Aq is the total # of logical cores (lcores) (8 maximum, MCE 1.521).
\& ## The computed value will not exceed the # of logical cores on the box.
\&
\& my $mce = MCE\->new(
\&
\& max_workers => \*(Aqauto\*(Aq,       ##  1 on HW with 1\-lcores;  2 on  2\-lcores
\& max_workers =>  16,          ## 16 on HW with 4\-lcores; 16 on 32\-lcores
\&
\& max_workers => \*(Aqauto\*(Aq,       ##  4 on HW with 4\-lcores;  8 on 16\-lcores
\& max_workers => \*(Aqauto*1.5\*(Aq,   ##  4 on HW with 4\-lcores; 12 on 16\-lcores
\& max_workers => \*(Aqauto*2.0\*(Aq,   ##  4 on HW with 4\-lcores; 16 on 16\-lcores
\& max_workers => \*(Aqauto/2.0\*(Aq,   ##  2 on HW with 4\-lcores;  4 on 16\-lcores
\& max_workers => \*(Aqauto+3\*(Aq,     ##  4 on HW with 4\-lcores; 11 on 16\-lcores
\& max_workers => \*(Aqauto\-1\*(Aq,     ##  3 on HW with 4\-lcores;  7 on 16\-lcores
\&
\& max_workers => MCE::Util::get_ncpu,   ## run on all lcores
\& );
.Ve
.PP
In summary:
.PP
.Vb 5
\& 1. Auto has an upper\-limit of 8 in MCE 1.521 (# of lcores, 8 maximum)
\& 2. Math may be applied with auto (*/+\-) to change the upper limit
\& 3. The computed value for auto will not exceed the total # of lcores
\& 4. One can specify max_workers explicitly to a hard value
\& 5. MCE::Util::get_ncpu returns the actual # of lcores
.Ve
.SH "ACKNOWLEDGMENTS"
.IX Header "ACKNOWLEDGMENTS"
The portable code for detecting the number of processors was adopted from
Test::Smoke::SysInfo.
.SH "INDEX"
.IX Header "INDEX"
\&\s-1MCE\s0, MCE::Core
.SH "AUTHOR"
.IX Header "AUTHOR"
Mario E. Roy, <marioeroy AT gmail DOT com>