nix: better monitoring loadtest report readability

nix/tools/loadtest.nix

@@ -231,6 +231,9 @@ let
 
         echo -e '\n\n## Process monitoring results\n'
 
+        echo 'Tracks the memory and CPU usage in 1 second intervals for the duration of the loadtest.'
+        echo -e 'If a branch finishes its loadtest in less seconds than another branch, it will have blank cells for the missing seconds.\n'
+
         find loadtest -type f -iname '*.csv' \
           | sort -nr \
           | ${mergeMonitorResults}

nix/tools/merge_monitor_result.py

@@ -9,16 +9,16 @@ merged = None
 paths = [p.strip() for p in sys.stdin.read().split() if p.strip()]
 
 for csv_path in paths:
-    # pfix is prefix (variable shortened to pass linter)
-    pfix = os.path.splitext(os.path.basename(csv_path))[0]
+    # br is branch (variable shortened to pass linter)
+    br = os.path.splitext(os.path.basename(csv_path))[0]
 
     df = pd.read_csv(csv_path)
 
     if KEY not in df.columns:
         sys.exit(f"{csv_path} is missing the {KEY} column")
 
-    # add prefix to every metric column
-    df = df.rename(columns={c: f"{pfix} {c}" for c in df.columns if c != KEY})
+    # add branch marker to every metric column
+    df = df.rename(columns={c: f"{c} [{br}]" for c in df.columns if c != KEY})
 
     # outer join so missing rows appear
     merged = df if merged is None else merged.merge(df, on=KEY, how="outer")