Improve thread pool management to render PKC snappier

resources/lib/backgroundthread.py

@@ -12,6 +12,7 @@ import xbmc
 
 from . import utils, app, variables as v
 
+WORKER_COUNT = 3
 LOG = getLogger('PLEX.threads')
 
 
@@ -346,6 +347,11 @@ class Task(object):
         return not self.finished and not self._canceled
 
 
+class ShutdownSentinel(Task):
+    def run(self):
+        pass
+
+
 class FunctionAsTask(Task):
     def __init__(self, function, callback, *args, **kwargs):
         self._function = function
@@ -372,7 +378,7 @@ class MutablePriorityQueue(Queue.PriorityQueue):
             lowest = self.queue and min(self.queue) or None
         except Exception:
             lowest = None
-            utils.ERROR()
+            utils.ERROR(notify=True)
         finally:
             self.mutex.release()
         return lowest
@@ -393,7 +399,7 @@ class BackgroundWorker(object):
         try:
             task._run()
         except Exception:
-            utils.ERROR()
+            utils.ERROR(notify=True)
 
     def abort(self):
         self._abort = True
@@ -423,13 +429,13 @@ class BackgroundWorker(object):
         except Queue.Empty:
             LOG.debug('(%s): Idle', self.name)
 
-    def shutdown(self):
+    def shutdown(self, block=True):
         self.abort()
 
         if self._task:
             self._task.cancel()
 
-        if self._thread and self._thread.isAlive():
+        if block and self._thread and self._thread.isAlive():
             LOG.debug('thread (%s): Waiting...', self.name)
             self._thread.join()
             LOG.debug('thread (%s): Done', self.name)
@@ -444,16 +450,17 @@ class NonstoppingBackgroundWorker(BackgroundWorker):
         super(NonstoppingBackgroundWorker, self).__init__(queue, name)
 
     def _queueLoop(self):
+        LOG.debug('Starting Worker %s', self.name)
         while not self.aborted():
-            try:
-                self._task = self._queue.get_nowait()
+            self._task = self._queue.get()
+            if self._task is ShutdownSentinel:
+                break
             self._working = True
             self._runTask(self._task)
             self._working = False
             self._queue.task_done()
             self._task = None
-            except Queue.Empty:
-                app.APP.monitor.waitForAbort(0.05)
+        LOG.debug('Exiting Worker %s', self.name)
 
     def working(self):
         return self._working
@@ -465,7 +472,10 @@ class BackgroundThreader:
         self._queue = MutablePriorityQueue()
         self._abort = False
         self.priority = -1
-        self.workers = [worker(self._queue, 'queue.{0}:worker.{1}'.format(self.name, x)) for x in range(worker_count)]
+        self.workers = [
+            worker(self._queue, 'queue.{0}:worker.{1}'.format(self.name, x))
+            for x in range(worker_count)
+        ]
 
     def _nextPriority(self):
         self.priority += 1
@@ -480,11 +490,11 @@ class BackgroundThreader:
     def aborted(self):
         return self._abort or xbmc.abortRequested
 
-    def shutdown(self):
+    def shutdown(self, block=True):
         self.abort()
-
+        self.addTasksToFront([ShutdownSentinel() for _ in self.workers])
         for w in self.workers:
-            w.shutdown()
+            w.shutdown(block)
 
     def addTask(self, task):
         task.priority = self._nextPriority()
@@ -537,7 +547,9 @@ class BackgroundThreader:
 
 
 class ThreaderManager:
-    def __init__(self, worker=BackgroundWorker, worker_count=6):
+    def __init__(self,
+                 worker=NonstoppingBackgroundWorker,
+                 worker_count=WORKER_COUNT):
         self.index = 0
         self.abandoned = []
         self._workerhandler = worker
@@ -557,10 +569,10 @@ class ThreaderManager:
         self.threader = BackgroundThreader(name=str(self.index),
                                            worker=self._workerhandler)
 
-    def shutdown(self):
-        self.threader.shutdown()
+    def shutdown(self, block=True):
+        self.threader.shutdown(block)
         for a in self.abandoned:
-            a.shutdown()
+            a.shutdown(block)
 
 
 BGThreader = ThreaderManager()

resources/lib/service_entry.py

@@ -544,6 +544,7 @@ class Service(object):
         # Tell all threads to terminate (e.g. several lib sync threads)
         LOG.debug('Aborting all threads')
         app.APP.stop_pkc = True
+        backgroundthread.BGThreader.shutdown(block=False)
         # Load/Reset PKC entirely - important for user/Kodi profile switch
         # Clear video nodes properties
         library_sync.clear_window_vars()