Do not initialize the user defined driver plugin in worker processes

src/calibre/customize/ui.py

@@ -452,6 +452,9 @@ def device_plugins(include_disabled=False): # {{{
         if isinstance(plugin, DevicePlugin):
             if include_disabled or not is_disabled(plugin):
                 if platform in plugin.supported_platforms:
+                    if getattr(plugin, 'plugin_needs_delayed_initialization',
+                            False):
+                        plugin.do_delayed_plugin_initialization()
                     yield plugin
 # }}}
 
@@ -496,7 +499,7 @@ def initialize_plugin(plugin, path_to_zip_file):
 def has_external_plugins():
     return bool(config['plugins'])
 
-def initialize_plugins():
+def initialize_plugins(perf=False):
     global _initialized_plugins
     _initialized_plugins = []
     conflicts = [name for name in config['plugins'] if name in
@@ -505,6 +508,10 @@ def initialize_plugins():
         remove_plugin(p)
     external_plugins = config['plugins']
     ostdout, ostderr = sys.stdout, sys.stderr
+    if perf:
+        from collections import defaultdict
+        import time
+        times = defaultdict(lambda:0)
     for zfp in list(external_plugins) + builtin_plugins:
         try:
             if not isinstance(zfp, type):
@@ -517,7 +524,11 @@ def initialize_plugins():
                 plugin = load_plugin(zfp) if not isinstance(zfp, type) else zfp
             except PluginNotFound:
                 continue
+            if perf:
+                st = time.time()
             plugin = initialize_plugin(plugin, None if isinstance(zfp, type) else zfp)
+            if perf:
+                times[plugin.name] = time.time() - st
             _initialized_plugins.append(plugin)
         except:
             print 'Failed to initialize plugin:', repr(zfp)
@@ -526,6 +537,9 @@ def initialize_plugins():
     # Prevent a custom plugin from overriding stdout/stderr as this breaks
     # ipython
     sys.stdout, sys.stderr = ostdout, ostderr
+    if perf:
+        for x in sorted(times, key=lambda x:times[x]):
+            print ('%50s: %.3f'%(x, times[x]))
     _initialized_plugins.sort(cmp=lambda x,y:cmp(x.priority, y.priority), reverse=True)
     reread_filetype_plugins()
     reread_metadata_plugins()

src/calibre/devices/user_defined/driver.py

@@ -90,6 +90,10 @@ class USER_DEFINED(USBMS):
     OPT_CARD_A_FOLDER           = 9
 
     def initialize(self):
+        self.plugin_needs_delayed_initialization = True
+        USBMS.initialize(self)
+
+    def do_delayed_plugin_initialization(self):
         try:
             e = self.settings().extra_customization
             self.VENDOR_ID          = int(e[self.OPT_USB_VENDOR_ID], 16)
@@ -107,4 +111,6 @@ class USER_DEFINED(USBMS):
         except:
             import traceback
             traceback.print_exc()
-        USBMS.initialize(self)
+        self.plugin_needs_delayed_initialization = False
+
+