--- a/python/mozbuild/mozbuild/controller/building.py
+++ b/python/mozbuild/mozbuild/controller/building.py
@@ -233,23 +233,26 @@ class BuildMonitor(MozbuildObject):
 
         try:
             warning = self._warnings_collector.process_line(line)
         except:
             pass
 
         return BuildOutputResult(warning, False, True)
 
-    def finish(self, record_usage=True):
-        """Record the end of the build."""
-        self.end_time = time.time()
-
+    def stop_resource_recording(self):
         if self._resources_started:
             self.resources.stop()
 
+        self._resources_started = False
+
+    def finish(self, record_usage=True):
+        """Record the end of the build."""
+        self.stop_resource_recording()
+        self.end_time = time.time()
         self._finder_end_cpu = self._get_finder_cpu_usage()
         self.elapsed = self.end_time - self.start_time
 
         self.warnings_database.prune()
         self.warnings_database.save_to_file(self._warnings_path)
 
         if not record_usage:
             return

--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -225,16 +225,21 @@ class BuildOutputManager(LoggingMixin):
         return self
 
     def __exit__(self, exc_type, exc_value, traceback):
         if self.footer:
             self.footer.clear()
             # Prevents the footer from being redrawn if logging occurs.
             self._handler.footer = None
 
+        # Ensure the resource monitor is stopped because leaving it running
+        # could result in the process hanging on exit because the resource
+        # collection child process hasn't been told to stop.
+        self.monitor.stop_resource_recording()
+
     def write_line(self, line):
         if self.footer:
             self.footer.clear()
 
         print(line)
 
         if self.footer:
             self.footer.draw()