perf(ci): skip loaded lines calculation on iterations after the first

Author: hebaalazzeh

scripts/import_profiler/profiler.py

@@ -40,7 +40,7 @@ def get_rss_mb():
     except Exception:
         return 0.0
 
-def run_worker(target_module):
+def run_worker(target_module, skip_line_count=False):
     """Performs ONE import and returns metrics."""
     tracemalloc.start()
     importlib.invalidate_caches()
@@ -66,33 +66,36 @@ def run_worker(target_module):
     new_modules = modules_after - modules_before
 
     loaded_lines = 0
-    for m in new_modules:
-        try:
-            file_path = sys.modules[m].__file__
-            if not file_path:
-                continue
+    if not skip_line_count:
+        for m in new_modules:
+            try:
+                file_path = sys.modules[m].__file__
+                if not file_path:
+                    continue
 
-            if file_path.endswith('.pyc'):
-                try:
-                    file_path = importlib.util.source_from_cache(file_path)
-                except ValueError:
-                    # Raised if the .pyc path does not follow standard PEP 3147/488 conventions.
-                    # We pass silently because the unresolved file_path will still end in '.pyc', 
-                    # meaning the subsequent '.endswith('.py')' check will fail and safely skip 
-                    # trying to count lines in a binary file.
-                    pass
-            if file_path.endswith('.py'):
-                try:
-                    with open(file_path, 'r', encoding='utf-8', errors='ignore') as f:
-                        loaded_lines += sum(1 for _ in f)
-                except OSError as e:
-                    print(f"WARNING: Failed to read lines from {file_path}: {e}", file=sys.stderr)
-        except KeyError:
-            # Module disappeared from sys.modules during execution
-            pass
-        except AttributeError:
-            # Module has no __file__ attribute (likely a C-extension or built-in)
-            pass
+                if file_path.endswith('.pyc'):
+                    try:
+                        file_path = importlib.util.source_from_cache(file_path)
+                    except ValueError:
+                        # Raised if the .pyc path does not follow standard PEP 3147/488 conventions.
+                        # We pass silently because the unresolved file_path will still end in '.pyc', 
+                        # meaning the subsequent '.endswith('.py')' check will fail and safely skip 
+                        # trying to count lines in a binary file.
+                        pass
+                if file_path.endswith('.py'):
+                    try:
+                        with open(file_path, 'r', encoding='utf-8', errors='ignore') as f:
+                            loaded_lines += sum(1 for _ in f)
+                    except OSError as e:
+                        print(f"WARNING: Failed to read lines from {file_path}: {e}", file=sys.stderr)
+            except KeyError:
+                # Module disappeared from sys.modules during execution
+                pass
+            except AttributeError:
+                # Module has no __file__ attribute (likely a C-extension or built-in)
+                pass
+    else:
+        loaded_lines = -1
 
     # Output to stdout for the Master to capture
     metrics = {
@@ -106,6 +109,8 @@ def run_worker(target_module):
 
 def _run_worker_and_parse(cmd):
     result = subprocess.run(cmd, capture_output=True, text=True, check=True)
+    if result.stderr.strip():
+        print(result.stderr.strip(), file=sys.stderr)
     try:
         lines = result.stdout.strip().splitlines()
         data = None
@@ -185,6 +190,8 @@ def run_master(iterations, target_module, cpu=0, csv_path=None, clear_cache=True
             cmd += ["taskset", "-c", str(cpu)]
 
         cmd += python_exe + [__file__, "--worker", f"--module={target_module}"]
+        if i > 0:
+            cmd += ["--skip-line-count"]
 
         try:
             data = _run_worker_and_parse(cmd)
@@ -194,11 +201,12 @@ def run_master(iterations, target_module, cpu=0, csv_path=None, clear_cache=True
             print(f"Iteration {i+1}/{iterations} completed in {data['time_ms']:.2f} ms")
             if i > 0 and loaded_modules_val != data["loaded_modules"]:
                 print(f"WARNING: Non-deterministic import behavior! Iteration {i+1} loaded {data['loaded_modules']} modules (expected {loaded_modules_val}).", file=sys.stderr)
-            if i > 0 and loaded_lines_val != data["loaded_lines"]:
-                print(f"WARNING: Non-deterministic import behavior! Iteration {i+1} loaded {data['loaded_lines']} lines (expected {loaded_lines_val}).", file=sys.stderr)
 
             loaded_modules_val = data["loaded_modules"]
-            loaded_lines_val = data["loaded_lines"]
+            if data["loaded_lines"] == -1:
+                data["loaded_lines"] = loaded_lines_val
+            else:
+                loaded_lines_val = data["loaded_lines"]
         except FileNotFoundError as e:
             if cpu != NO_CPU_PINNING and cmd and cmd[0] == "taskset":
                 print("ERROR: 'taskset' command not found. CPU pinning is enabled but taskset is not installed. "
@@ -442,6 +450,7 @@ def find_module_from_package(pkg):
     parser.add_argument("--diff-baseline", help="Path to a baseline CSV file to compare against.")
     parser.add_argument("--diff-threshold", type=float, default=100.0, help="Fail if Median time exceeds baseline Median by this many ms.")
     parser.add_argument("--worker", action="store_true", help=argparse.SUPPRESS)
+    parser.add_argument("--skip-line-count", action="store_true", help=argparse.SUPPRESS)
 
     args = parser.parse_args()
 
@@ -450,7 +459,7 @@ def find_module_from_package(pkg):
         target_module = find_module_from_package(args.package)
 
     if args.worker:
-        run_worker(target_module)
+        run_worker(target_module, skip_line_count=args.skip_line_count)
     elif args.trace:
         if not args.keep_pycache: clean_bytecode()
         run_trace(target_module)