Try listing out all the subprocesses created by telemetry at the end.

BUG=536862

Review URL: https://codereview.chromium.org/1378563003

Cr-Commit-Position: refs/heads/master@{#352047}

1 files changed, 34 insertions, 2 deletions

diff --git a/tools/telemetry/telemetry/internal/util/global_hooks.py b/tools/telemetry/telemetry/internal/util/global_hooks.py
index b1541e9..8fe80d0 100644
--- a/tools/telemetry/telemetry/internal/util/global_hooks.py
+++ b/tools/telemetry/telemetry/internal/util/global_hooks.py
@@ -3,9 +3,11 @@
 # found in the LICENSE file.
 
 """Hooks that apply globally to all scripts that import or use Telemetry."""
-
+import atexit
+import os
 import signal
 import sys
+import logging
 
 from telemetry.internal.util import exception_formatter
 
@@ -14,7 +16,7 @@ def InstallHooks():
   InstallUnhandledExceptionFormatter()
   InstallStackDumpOnSigusr1()
   InstallTerminationHook()
-
+  InstallListStrayProcessesUponExitHook()
 
 def InstallUnhandledExceptionFormatter():
   """Print prettier exceptions that also contain the stack frame's locals."""
@@ -40,3 +42,33 @@ def InstallTerminationHook():
     exception_formatter.PrintFormattedFrame(stack_frame, exception_string)
     sys.exit(-1)
   signal.signal(signal.SIGTERM, PrintStackAndExit)
+
+
+def InstallListStrayProcessesUponExitHook():
+  def _ListAllSubprocesses():
+    try:
+      import psutil
+    except ImportError:
+      logging.error(
+          'psutil is not installed on the system. Not listing possible '
+          'leaked processes. To install psutil, see: '
+          'https://pypi.python.org/pypi/psutil')
+    telemetry_pid = os.getpid()
+    parent = psutil.Process(telemetry_pid)
+    if hasattr(parent, 'children'):
+      children = parent.children(recursive=True)
+    else:  # Some old version of psutil use get_children instead children.
+      children = parent.get_children()
+    if children:
+      leak_processes_info = []
+      for p in children:
+        process_info = '%s (%s)' % (p.name(), p.pid)
+        try:
+          process_info += ' - %s' % p.cmdline()
+        except Exception:
+          pass
+        leak_processes_info.append(process_info)
+      logging.error('Telemetry leaks these processes: %s',
+                    ', '.join(leak_processes_info))
+
+  atexit.register(_ListAllSubprocesses)