Proper fix for switch library mem leak (I hope)

src/calibre/gui2/actions/choose_library.py

@@ -384,14 +384,28 @@ class ChooseLibraryAction(InterfaceAction):
             return
 
         prefs['library_path'] = loc
-        #from calibre.utils.mem import memory
+        from calibre.utils.mem import memory
-        #import weakref, gc
+        import weakref
-        #ref = weakref.ref(self.gui.library_view.model().db)
+        from PyQt4.Qt import QTimer
-        #before = memory()/1024**2
+        self.dbref = weakref.ref(self.gui.library_view.model().db)
+        self.before_mem = memory()/1024**2
         self.gui.library_moved(loc)
-        #print gc.get_referrers(ref)[0]
+        QTimer.singleShot(1000, self.debug_leak)
-        #for i in xrange(3): gc.collect()
+
-        #print 'leaked:', memory()/1024**2 - before
+    def debug_leak(self):
+        import gc
+        from calibre.utils.mem import memory
+        ref = self.dbref
+        for i in xrange(3): gc.collect()
+        if ref() is not None:
+            print 11111, ref()
+            for r in gc.get_referrers(ref())[:10]:
+                print r
+                print
+        print 'before:', self.before_mem
+        print 'after:', memory()/1024**2
+        self.dbref = self.before_mem = None
+
 
     def qs_requested(self, idx, *args):
         self.switch_requested(self.qs_locations[idx])

src/calibre/gui2/main.py

@@ -150,13 +150,13 @@ class GuiRunner(QObject):
         if DEBUG:
             prints('Starting up...')
 
-    def start_gui(self):
+    def start_gui(self, db):
         from calibre.gui2.ui import Main
         main = Main(self.opts, gui_debug=self.gui_debug)
         if self.splash_screen is not None:
             self.splash_screen.showMessage(_('Initializing user interface...'))
             self.splash_screen.finish(main)
-        main.initialize(self.library_path, self.db, self.listener, self.actions)
+        main.initialize(self.library_path, db, self.listener, self.actions)
         if DEBUG:
             prints('Started up in', time.time() - self.startup_time)
         add_filesystem_book = partial(main.iactions['Add Books'].add_filesystem_book, allow_device=False)
@@ -200,8 +200,7 @@ class GuiRunner(QObject):
                     det_msg=traceback.format_exc(), show=True)
                 self.initialization_failed()
 
-        self.db = db
+        self.start_gui(db)
-        self.start_gui()
 
     def initialize_db(self):
         db = None

src/calibre/gui2/tag_view.py

@@ -114,6 +114,9 @@ class TagsView(QTreeView): # {{{
 
     def set_database(self, db, tag_match, sort_by):
         self.hidden_categories = config['tag_browser_hidden_categories']
+        old = getattr(self, '_model', None)
+        if old is not None:
+            old.break_cycles()
         self._model = TagsModel(db, parent=self,
                                 hidden_categories=self.hidden_categories,
                                 search_restriction=None,
@@ -371,6 +374,9 @@ class TagsView(QTreeView): # {{{
     # model. Reason: it is much easier than reconstructing the browser tree.
     def set_new_model(self, filter_categories_by=None):
         try:
+            old = getattr(self, '_model', None)
+            if old is not None:
+                old.break_cycles()
             self._model = TagsModel(self.db, parent=self,
                                     hidden_categories=self.hidden_categories,
                                     search_restriction=self.search_restriction,
@@ -544,6 +550,9 @@ class TagsModel(QAbstractItemModel): # {{{
                     tooltip=tt, category_key=r)
         self.refresh(data=data)
 
+    def break_cycles(self):
+        self.db = self.root_item = None
+
     def mimeTypes(self):
         return ["application/calibre+from_library"]
 
@@ -1109,8 +1118,7 @@ class TagBrowserMixin(object): # {{{
 
     def __init__(self, db):
         self.library_view.model().count_changed_signal.connect(self.tags_view.recount)
-        self.tags_view.set_database(self.library_view.model().db,
+        self.tags_view.set_database(db, self.tag_match, self.sort_by)
-                self.tag_match, self.sort_by)
         self.tags_view.tags_marked.connect(self.search.set_search_string)
         self.tags_view.tag_list_edit.connect(self.do_tags_list_edit)
         self.tags_view.user_category_edit.connect(self.do_user_categories_edit)

src/calibre/library/caches.py

@@ -42,6 +42,9 @@ class MetadataBackup(Thread): # {{{
 
     def stop(self):
         self.keep_running = False
+        # Break cycles so that this object doesn't hold references to db
+        self.do_write = self.get_metadata_for_dump = self.clear_dirtied = \
+            self.set_dirtied = self.db = None
 
     def run(self):
         while self.keep_running:
@@ -185,6 +188,11 @@ class ResultCache(SearchQueryParser): # {{{
         self.build_date_relop_dict()
         self.build_numeric_relop_dict()
 
+    def break_cycles(self):
+        self._data = self.field_metadata = self.FIELD_MAP = \
+            self.numeric_search_relops = self.date_search_relops = \
+            self.all_search_locations = None
+
 
     def __getitem__(self, row):
         return self._data[self._map_filtered[row]]

src/calibre/library/database2.py

@@ -362,7 +362,9 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         self.last_update_check = self.last_modified()
 
     def break_cycles(self):
-        self.data = self.field_metadata = self.prefs = self.listeners = None
+        self.data.break_cycles()
+        self.data = self.field_metadata = self.prefs = self.listeners = \
+            self.refresh_ondevice = None
 
     def initialize_database(self):
         metadata_sqlite = open(P('metadata_sqlite.sql'), 'rb').read()