feat: Implement robust process group management and timeouts in BashTool

Refactors BashTool to use start_new_session=True and os.killpg for proper process isolation and cleanup on timeouts or errors.

PiperOrigin-RevId: 893740978

Author: shukladivyansh

.github/.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "1.28.1"
+  ".": "1.28.0"
 }

CHANGELOG.md

@@ -1,18 +1,5 @@
 # Changelog
 
-## [1.28.1](https://github.com/google/adk-python/compare/v1.28.0...v1.28.1) (2026-04-02)
-
-
-### Features
-
-* **live:** support live for `gemini-3.1-flash-live-preview` model ([ee69661](https://github.com/google/adk-python/commit/ee69661a616056fa89e0ec2188aaa59bd714d8c9))
-
-
-### Bug Fixes
-
-* Disallow args on /builder and Add warning about Web UI usage to CLI help ([f037f68](https://github.com/google/adk-python/commit/f037f68d67ae1bd16b00df0c7523fb67cbd1e911))
-* **live:** Buffer tool calls and emit them together upon turn completion ([081adbd](https://github.com/google/adk-python/commit/081adbdfa41490e4868b028a1cdabceb811a7505))
-
 ## [1.28.0](https://github.com/google/adk-python/compare/v1.27.5...v1.28.0) (2026-03-26)
 
 

src/google/adk/tools/bash_tool.py

@@ -18,8 +18,11 @@
 
 import asyncio
 import dataclasses
+import logging
+import os
 import pathlib
 import shlex
+import signal
 from typing import Any
 from typing import Optional
 
@@ -132,26 +135,74 @@ async def run_async(
     elif not tool_context.tool_confirmation.confirmed:
       return {"error": "This tool call is rejected."}
 
-    process = await asyncio.create_subprocess_exec(
-        *shlex.split(command),
-        cwd=str(self._workspace),
-        stdout=asyncio.subprocess.PIPE,
-        stderr=asyncio.subprocess.PIPE,
-    )
+    stdout = None
+    stderr = None
     try:
-      stdout, stderr = await asyncio.wait_for(process.communicate(), timeout=30)
+      process = await asyncio.create_subprocess_exec(
+          *shlex.split(command),
+          cwd=str(self._workspace),
+          stdout=asyncio.subprocess.PIPE,
+          stderr=asyncio.subprocess.PIPE,
+          start_new_session=True,
+      )
+
+      try:
+        stdout, stderr = await asyncio.wait_for(
+            process.communicate(), timeout=30
+        )
+      except asyncio.TimeoutError:
+        try:
+          os.killpg(process.pid, signal.SIGKILL)
+        except ProcessLookupError:
+          pass
+        stdout, stderr = await process.communicate()
+        return {
+            "error": "Command timed out after 30 seconds.",
+            "stdout": (
+                stdout.decode(errors="replace")
+                if stdout
+                else "<no stdout captured>"
+            ),
+            "stderr": (
+                stderr.decode(errors="replace")
+                if stderr
+                else "<no stderr captured>"
+            ),
+            "returncode": process.returncode,
+        }
+      finally:
+        try:
+          if process.pid:
+            os.killpg(process.pid, signal.SIGKILL)
+        except ProcessLookupError:
+          pass
+
       return {
           "stdout": (
-              stdout.decode() if stdout is not None else "<No stdout captured>"
+              stdout.decode(errors="replace")
+              if stdout
+              else "<no stdout captured>"
           ),
           "stderr": (
-              stderr.decode() if stderr is not None else "<No stderr captured>"
+              stderr.decode(errors="replace")
+              if stderr
+              else "<no stderr captured>"
           ),
           "returncode": process.returncode,
       }
-    except asyncio.TimeoutError:
-      try:
-        process.kill()
-      except ProcessLookupError:
-        pass
-      return {"error": "Command timed out after 30 seconds."}
+    except Exception as e:  # pylint: disable=broad-except
+      logger = logging.getLogger("google_adk." + __name__)
+      logger.exception("ExecuteBashTool execution failed")
+
+      stdout_res = (
+          stdout.decode(errors="replace") if stdout else "<no stdout captured>"
+      )
+      stderr_res = (
+          stderr.decode(errors="replace") if stderr else "<no stderr captured>"
+      )
+
+      return {
+          "error": f"Execution failed: {str(e)}",
+          "stdout": stdout_res,
+          "stderr": stderr_res,
+      }

src/google/adk/version.py

@@ -13,4 +13,4 @@
 # limitations under the License.
 
 # version: major.minor.patch
-__version__ = "1.28.1"
+__version__ = "1.28.0"

tests/unittests/tools/test_bash_tool.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import asyncio
+import signal
 from unittest import mock
 
 from google.adk.tools import bash_tool
@@ -203,6 +204,8 @@ async def test_nonzero_returncode(self, workspace, tool_context_confirmed):
   async def test_timeout(self, workspace, tool_context_confirmed):
     tool = bash_tool.ExecuteBashTool(workspace=workspace)
     mock_process = mock.AsyncMock()
+    mock_process.pid = 12345
+    mock_process.communicate.return_value = (b"", b"")
     with (
         mock.patch.object(
             asyncio,
@@ -213,14 +216,15 @@ async def test_timeout(self, workspace, tool_context_confirmed):
         mock.patch.object(
             asyncio, "wait_for", autospec=True, side_effect=asyncio.TimeoutError
         ),
+        mock.patch("os.killpg") as mock_killpg,
     ):
       result = await tool.run_async(
           args={"command": "python scripts/do_thing.py"},
           tool_context=tool_context_confirmed,
       )
+      mock_killpg.assert_called_with(12345, signal.SIGKILL)
     assert "error" in result
     assert "timed out" in result["error"].lower()
-    mock_process.kill.assert_called_once()
 
   @pytest.mark.asyncio
   async def test_cwd_is_workspace(self, workspace, tool_context_confirmed):