Speedup jsonnet generation by them running in parallel

Previously, jsonnet to yaml conversion was done sequentially and this
took quite some time. The patch speeds that up by running them in
parallel . The number of jobs to run in parallel is determined by the
number of CPU cores (thus requires nproc to be in path).

Signed-off-by: Sunil Thaha <[email protected]>

Author: sthaha

hack/build-jsonnet.sh

@@ -22,15 +22,26 @@ while IFS= read -r line; do
 	files+=("$line")
 done < <(jq -r 'keys[]' "${TMP}/main.json")
 
-for file in "${files[@]}"
-do
-	dir=$(dirname "${file}")
-	path="${prefix}/${dir}"
-	mkdir -p "${path}"
-	# convert file name from camelCase to snake-case
-	fullfile=$(echo "${file}" | sed 's/\(.\)\([A-Z]\)/\1-\2/g' | tr '[:upper:]' '[:lower:]')
-	jq -r ".[\"${file}\"]" "${TMP}/main.json" | gojsontoyaml > "${prefix}/${fullfile}.yaml"
+maxProc=$(nproc || echo 4)
+
+# process all files in parallel
+for file in "${files[@]}"; do
+	{
+		dir=$(dirname "${file}")
+		path="${prefix}/${dir}"
+		mkdir -p "${path}"
+
+		# convert file name from camelCase to snake-case
+		fullfile=$(echo "${file}" | sed 's/\(.\)\([A-Z]\)/\1-\2/g' | tr '[:upper:]' '[:lower:]')
+		jq -r ".[\"${file}\"]" "${TMP}/main.json" | gojsontoyaml > "${prefix}/${fullfile}.yaml"
+	}&
+
+	# wait for at least one of the jobs to finish if there are more than maxProc jobs
+	while [[ $(jobs -r | wc -l ) -ge "$maxProc" ]]; do wait -n; done
 done
+# wait for all jobs to finish
+wait
+
 
 # shellcheck disable=SC1003
 # Produce dashboard definitions in format understandable by CVO (it doesn't accept ConfigMapList)