commit: d9cde86b8e01a04b09c3cc7fb328d92428594828
Author: Michał Górny <mgorny <AT> gentoo <DOT> org>
AuthorDate: Tue Dec 13 09:08:22 2016 +0000
Commit: Michał Górny <mgorny <AT> gentoo <DOT> org>
CommitDate: Sun Dec 18 13:46:42 2016 +0000
URL: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=d9cde86b
multiprocessing.eclass: Introduce get_nproc() to get no of CPUs
Introduce get_nproc(), a portable 'nproc' wrapper. It uses either
'nproc' or a fallback Python multiprocessing module call to attempt to
determine the number of available processing units.
This can be used e.g. to determine a safe number of jobs to run when
MAKEOPTS specifies unlimited --jobs and the build system in question
does not support --load-average.
eclass/multiprocessing.eclass | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/eclass/multiprocessing.eclass b/eclass/multiprocessing.eclass
index 5a5fe9a..3c5dfff 100644
--- a/eclass/multiprocessing.eclass
+++ b/eclass/multiprocessing.eclass
@@ -53,6 +53,38 @@ bashpid() {
sh -c 'echo ${PPID}'
}
+# @FUNCTION: get_nproc
+# @USAGE: [${fallback:-1}]
+# @DESCRIPTION:
+# Attempt to figure out the number of processing units available.
+# If the value can not be determined, prints the provided fallback
+# instead. If no fallback is provided, defaults to 1.
+get_nproc() {
+ local nproc
+
+ # GNU
+ if type -P nproc &>/dev/null; then
+ nproc=$(nproc)
+ fi
+
+ # BSD
+ if [[ -z ${nproc} ]] && type -P sysctl &>/dev/null; then
+ nproc=$(sysctl -n hw.ncpu 2>/dev/null)
+ fi
+
+ # fallback to python2.6+
+ # note: this may fail (raise NotImplementedError)
+ if [[ -z ${nproc} ]] && type -P python &>/dev/null; then
+ nproc=$(python -c 'import multiprocessing;
print(multiprocessing.cpu_count());' 2>/dev/null)
+ fi
+
+ if [[ -n ${nproc} ]]; then
+ echo "${nproc}"
+ else
+ echo "${1:-1}"
+ fi
+}
+
# @FUNCTION: makeopts_jobs
# @USAGE: [${MAKEOPTS}]
# @DESCRIPTION:
