memory-monitor: Simplify cgroup task handling in the handler script.

Simplify the process of extracting PIDs from a cgroup. Instead of using
a temporary file and filtering tasks to find unique PIDs based on TIDs,
the script now directly reads the `cgroup.procs` file to retrieve the
PIDs. This approach reduces complexity, removes the need for
intermediate processing, and improves the efficiency of PID retrieval.
The redundant temporary task list creation has been removed to
streamline the code.

Signed-off-by: Nikolay Martyanov <[email protected]>

pkg/memory-monitor/src/monitor/memory-monitor-handler.sh

@@ -11,23 +11,11 @@ find_pids_of_cgroup() {
     path=$1
     tempfile=$2
 
-    # Get a copy of the list of tasks in the cgroup, not to block the cgroup while handling
-    tmp_tasks=$(mktemp)
-    cat "$path"/tasks > "$tmp_tasks"
-
-    # List all tasks, filter out unique PIDs
-    while read -r tid; do
-      if [ -z "$tid" ]; then
-        continue
-      fi
-      # Find the main PID for each TID
-      pid=$(awk '/^Tgid:/ {print $2}' "/proc/$tid/status" 2>/dev/null)
-      if [ -n "$pid" ]; then
+    # Get the PIDs of the cgroup
+    pids=$(cat "$path"/cgroup.procs)
+    for pid in $pids; do
         echo "$pid" >> "$tempfile"
-      fi
-    done < "$tmp_tasks"
-
-    rm "$tmp_tasks"
+    done
 
     # Recurse into subdirectories
     for subdir in "$path"/*/; do