Workaround for SSIPClient using non-daemonic thread and therefore hanging interpreter shutdown

src/calibre/gui2/tts/implementation.py

@@ -9,5 +9,5 @@ if iswindows:
 elif ismacos:
     pass
 else:
-    from .linux import speak_simple_text
+    from .linux import Client
-    speak_simple_text
+    Client

src/calibre/gui2/tts/linux.py

@@ -2,29 +2,30 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2020, Kovid Goyal <kovid at kovidgoyal.net>
 
-import atexit
 from .errors import TTSSystemUnavailable
 
 
-def get_client():
+class Client:
-    client = getattr(get_client, 'ans', None)
-    if client is not None:
-        return client
-    from speechd.client import SSIPClient, SpawnError
-    try:
-        client = get_client.ans = SSIPClient('calibre')
-    except SpawnError as err:
-        raise TTSSystemUnavailable(_('Could not find speech-dispatcher on your system. Please install it.'), str(err))
-    atexit.register(client.close)
-    return client
 
+    def __init__(self):
+        self.create_ssip_client()
 
-def speak_simple_text(text):
+    def create_ssip_client(self):
-    client = get_client()
+        from speechd.client import SSIPClient, SpawnError
-    from speechd.client import SSIPCommunicationError
+        try:
-    try:
+            self.ssip_client = SSIPClient('calibre')
-        client.speak(text)
+        except SpawnError as err:
-    except SSIPCommunicationError:
+            raise TTSSystemUnavailable(_('Could not find speech-dispatcher on your system. Please install it.'), str(err))
-        get_client.ans = None
+
-        client = get_client()
+    def __del__(self):
-        client.speak(text)
+        self.ssip_client.close()
+        del self.ssip_client
+
+    def speak_simple_text(self, text):
+        from speechd.client import SSIPCommunicationError
+        try:
+            self.ssip_client.speak(text)
+        except SSIPCommunicationError:
+            self.ssip_client.close()
+            self.create_ssip_client()
+            self.ssip_client.speak(text)

src/calibre/gui2/viewer/ui.py

@@ -674,6 +674,7 @@ class EbookViewer(MainWindow):
             return
         self.shutting_down = True
         self.search_widget.shutdown()
+        self.web_view.shutdown()
         try:
             self.save_state()
             self.save_annotations()

src/calibre/gui2/viewer/web_view.py

@@ -467,6 +467,7 @@ class WebView(RestartingWebEngineView):
 
     def __init__(self, parent=None):
         self._host_widget = None
+        self._tts_client = None
         self.callback_id_counter = count()
         self.callback_map = {}
         self.current_cfi = self.current_content_file = None
@@ -529,9 +530,18 @@ class WebView(RestartingWebEngineView):
             self.inspector = Inspector(parent.inspector_dock.toggleViewAction(), self)
             parent.inspector_dock.setWidget(self.inspector)
 
+    @property
+    def tts_client(self):
+        if self._tts_client is None:
+            from calibre.gui2.tts.implementation import Client
+            self._tts_client = Client()
+        return self._tts_client
+
     def speak_simple_text(self, text):
-        from calibre.gui2.tts.implementation import speak_simple_text
+        self.tts_client.speak_simple_text(text)
-        speak_simple_text(text)
+
+    def shutdown(self):
+        self._tts_client = None
 
     def set_shortcut_map(self, smap):
         self.shortcut_map = smap