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 | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/eclass/multiprocessing.eclass b/eclass/multiprocessing.eclass
index 5a5fe9acb56a..0d241cdc15b6 100644
--- a/eclass/multiprocessing.eclass
+++ b/eclass/multiprocessing.eclass
@@ -53,6 +53,31 @@ 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
+
+ if type -P nproc &>/dev/null; then
+ # GNU
+ nproc=$(nproc)
+ elif type -P python &>/dev/null; then
+ # fallback to python2.6+
+ # note: this may fail (raise NotImplementedError)
+ nproc=$(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:
--
2.11.0
