Address comments

Author: ivonastojanovic

Doc/library/profiling.sampling.rst

@@ -1491,6 +1491,20 @@ Output options
    named ``<format>_<PID>.<ext>`` (for example, ``flamegraph_12345.html``).
    :option:`--heatmap` creates a directory named ``heatmap_<PID>``.
 
+   For HTML outputs (:option:`--flamegraph` and :option:`--heatmap`), the
+   generated file or directory is automatically opened in your default web
+   browser after profiling completes. Use :option:`--no-browser` to disable
+   this behavior. When using :option:`--subprocesses`, only the main process
+   output is opened automatically to avoid opening multiple browser tabs.
+
+.. option:: --no-browser
+
+   Disable automatic browser opening for HTML output (:option:`--flamegraph`
+   and :option:`--heatmap`). By default, HTML visualizations are opened in
+   your default web browser after generation. When profiling with
+   :option:`--subprocesses`, only the main process opens the browser by
+   default; subprocess outputs are never auto-opened.
+
 
 pstats display options
 ----------------------

Lib/profiling/sampling/cli.py

@@ -148,6 +148,9 @@ def _build_child_profiler_args(args):
     if args.format != "pstats":
         child_args.append(f"--{args.format}")
 
+    # Always add --no-browser for child profilers to avoid opening multiple browser tabs
+    child_args.append("--no-browser")
+
     return child_args
 
 
@@ -496,7 +499,8 @@ def _add_format_options(parser, include_compression=True, include_binary=True):
     output_group.add_argument(
         "--no-browser",
         action="store_true",
-        help="Disable automatic browser opening for HTML output (flamegraph, heatmap)",
+        help="Disable automatic browser opening for HTML output (flamegraph, heatmap). "
+        "When using --subprocesses, only the main process opens the browser by default",
     )
 
 
@@ -613,14 +617,14 @@ def _open_in_browser(path):
         if os.path.exists(index_path):
             abs_path = index_path
         else:
-            print(f"Warning: Could not find index.html in {path}")
+            print(f"Warning: Could not find index.html in {path}", file=sys.stderr)
             return
 
     file_url = f"file://{abs_path}"
     try:
         webbrowser.open(file_url)
     except Exception as e:
-        print(f"Warning: Could not open browser: {e}")
+        print(f"Warning: Could not open browser: {e}", file=sys.stderr)
 
 
 def _handle_output(collector, args, pid, mode):

Lib/test/test_profiling/test_sampling_profiler/test_children.py

@@ -438,6 +438,11 @@ def assert_flag_value_pair(flag, value):
             child_args,
             f"Flag '--flamegraph' not found in args: {child_args}",
         )
+        self.assertIn(
+            "--no-browser",
+            child_args,
+            f"Flag '--no-browser' not found in args: {child_args}",
+        )
 
     def test_build_child_profiler_args_no_gc(self):
         """Test building CLI args with --no-gc."""
@@ -992,6 +997,7 @@ def test_subprocesses_flag_with_flamegraph_output(self):
                     "-r",
                     "100",
                     "--flamegraph",
+                    "--no-browser",
                     "-o",
                     output_file,
                     script_file,