diff --git a/build.gradle b/build.gradle
index ec00f11..64f09d7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1343,6 +1343,9 @@
             println "Start executing test ${desc.name} [${desc.className}]"
         }
         afterTest { desc, result ->
+            if (project.hasProperty('update_test_timestamp')) {
+                file(project.getProperty('update_test_timestamp')).text = new Date().getTime()
+            }
             println "Done executing test ${desc.name} [${desc.className}] with result: ${result.resultType}"
         }
     }
diff --git a/tools/archive.py b/tools/archive.py
index ad58bca..013ff15 100755
--- a/tools/archive.py
+++ b/tools/archive.py
@@ -79,7 +79,7 @@
   return GetVersionDestination('http://storage.googleapis.com/', '', is_master)
 
 def Main():
-  if not 'BUILDBOT_BUILDERNAME' in os.environ:
+  if utils.is_bot():
     raise Exception('You are not a bot, don\'t archive builds')
 
   # Generate an r8-ed build without dependencies.
diff --git a/tools/test.py b/tools/test.py
index e4433b3..d9dca9f 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -12,6 +12,8 @@
 import optparse
 import subprocess
 import sys
+import thread
+import time
 import utils
 import notify
 
@@ -25,6 +27,14 @@
     "4.4.4",
     "4.0.4"]
 
+# How often do we check for progress on the bots:
+# Should be long enough that a normal run would always have med progress
+# Should be short enough that we ensure that two calls are close enough
+# to happen before bot times out.
+# A false positiv, i.e., printing the stacks of non hanging processes
+# is not a problem, no harm done except some logging in the stdout.
+TIMEOUT_HANDLER_PERIOD = 60 * 18
+
 def ParseOptions():
   result = optparse.OptionParser()
   result.add_option('--no-internal', '--no_internal',
@@ -95,7 +105,7 @@
 
 def Main():
   (options, args) = ParseOptions()
-  if 'BUILDBOT_BUILDERNAME' in os.environ:
+  if utils.is_bot():
     gradle.RunGradle(['clean'])
 
   # Build R8lib with dependencies for bootstrapping tests before adding test sources
@@ -171,6 +181,12 @@
                                     '%s.tar.gz' % sha1)
       utils.unpack_archive('%s.tar.gz' % sha1)
 
+  if utils.is_bot() and not utils.IsWindows():
+    timestamp_file = os.path.join(utils.BUILD, 'last_test_time')
+    if os.path.exists(timestamp_file):
+      os.remove(timestamp_file)
+    gradle_args.append('-Pupdate_test_timestamp=' + timestamp_file)
+    thread.start_new_thread(timeout_handler, (timestamp_file,))
 
   # Now run tests on selected runtime(s).
   vms_to_test = [options.dex_vm] if options.dex_vm != "all" else ALL_ART_VMS
@@ -193,6 +209,45 @@
 
   return 0
 
+
+def print_jstacks():
+  processes = subprocess.check_output(['ps', 'aux'])
+  for l in processes.splitlines():
+    if 'java' in l and 'openjdk' in l:
+      # Example line:
+      # ricow    184313  2.6  0.0 36839068 31808 ?      Sl   09:53   0:00 /us..
+      columns = l.split()
+      pid = columns[1]
+      return_value = subprocess.call(['jstack', pid])
+      if return_value:
+        print('Could not jstack %s' % l)
+  print('----') # May be eaten by gradle prints.
+  print('----') # May be eaten by gradle prints.
+
+def get_time_from_file(timestamp_file):
+  if os.path.exists(timestamp_file):
+    timestamp = os.stat(timestamp_file).st_mtime
+    print('TIMEOUT HANDLER timestamp: %s' % (timestamp))
+    print('---') # May be eaten by gradle prints.
+    print('---') # May be eaten by gradle prints.
+    sys.stdout.flush()
+    return timestamp
+  else:
+    print('TIMEOUT HANDLER no timestamp file yet')
+    print('---') # May be eaten by gradle prints.
+    print('---') # May be eaten by gradle prints.
+    sys.stdout.flush()
+    return None
+
+def timeout_handler(timestamp_file):
+  last_timestamp = None
+  while True:
+    time.sleep(TIMEOUT_HANDLER_PERIOD)
+    new_timestamp = get_time_from_file(timestamp_file)
+    if last_timestamp and new_timestamp == last_timestamp:
+      print_jstacks()
+    last_timestamp = new_timestamp
+
 if __name__ == '__main__':
   return_code = Main()
   if return_code != 0:
diff --git a/tools/utils.py b/tools/utils.py
index d2c4935..5355ba8 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -313,3 +313,6 @@
 
 def get_android_jar(api):
   return os.path.join(REPO_ROOT, ANDROID_JAR.format(api=api))
+
+def is_bot():
+  return 'BUILDBOT_BUILDERNAME' in os.environ