Fix #3086: Adjust node max_old_space_size to a percentage of availabl…

…e container memory (#3099)

agent/bin/launch_node.sh

@@ -1,5 +1,8 @@
 #!/usr/bin/env bash
 
+OLD_SPACE_SIZE_PERCENT=${OLD_SPACE_SIZE_PERCENT:-80}
+CGROUP_FILE='/sys/fs/cgroup/memory/memory.limit_in_bytes'
+
 # Ensure that we have a suitable node interpreter.  This ought to be declared declaratively in the package.json, within an engines section,
 # but we currently don't install the package so this wouldn't be enforced.
 REQUIRED_NODE_MAJOR=6
@@ -13,4 +16,19 @@ if [[ ! -z "${_NODE_OPTIONS}" ]]; then
     set -- ${_NODE_OPTIONS} "${@}"
 fi
 
+# Set max_old_space_size w.r.t the container's memory, unless caller has supplied --max_old_space_size
+for arg; do
+  if [[ "${arg}" =~ ^--max_old_space_size.* ]]; then
+    OLD_SPACE_SIZE_PERCENT=0
+    break
+  fi
+done
+
+if [[ -f "${CGROUP_FILE}" && "${OLD_SPACE_SIZE_PERCENT}" -gt 0 ]]; then
+    CONTAINTER_BYTES=$(cat ${CGROUP_FILE})
+    MAX_OLD_SPACE_SIZE=$(( ${CONTAINTER_BYTES} / 100 * ${OLD_SPACE_SIZE_PERCENT} ))
+    MAX_OLD_SPACE_SIZE_MI=$(( ${MAX_OLD_SPACE_SIZE} / ( 1024 * 1024 ) ))
+    set -- "--max_old_space_size=${MAX_OLD_SPACE_SIZE_MI}" "${@}"
+fi
+
 exec node "${@}"