Index: smart/fetcher.py
===================================================================
--- smart/fetcher.py	(revision 886)
+++ smart/fetcher.py	(working copy)
@@ -1457,37 +1457,49 @@
         self._active = {}   # handle -> (scheme, host)
         self._inactive = {} # handle -> (user, host, port)
         self._activelimit = {} # host -> num
-        self._running = False
         self._multi = pycurl.CurlMulti()
-        self._lock = thread.allocate_lock()
 
-    def tick(self):
+    def perform(self):
+        """Ask Curl to download files.
+
+        @return: True if there is still something to do.
+        """
         import pycurl
+        res, num = self._multi.perform()
+        if res == pycurl.E_CALL_MULTI_PERFORM:
+            return True
+        return False
 
-        if not self._running and self._queue:
-            self._running = True
-            thread.start_new_thread(self.perform, ())
+    def deactivate_handle(self, handle):
+        del self._active[handle]
+        self._multi.remove_handle(handle)
+        url = handle.item.getURL()
+        self._inactive[handle] = (url.user, url.host, url.port)
 
+    def stop(self):
+        FetcherHandler.stop(self)
+        # XXX This should not be needed, but somehow it seems to help
+        #     in cases where pycurl segfaults.
+        self._multi = pycurl.CurlMulti()
+
+    def tick(self):
+        import pycurl
+
         fetcher = self._fetcher
-        multi = self._multi
 
         if self._cancel:
-            self._lock.acquire()
-            for handle in self._active:
-                item = handle.item
-                item.setCancelled()
-                url = item.getURL()
-                multi.remove_handle(handle)
-                userhost = (url.user, url.host, url.port)
+            for handle in list(self._active):
+                handle.item.setCancelled()
+                self.deactivate_handle(handle)
             self._active.clear()
-            self._lock.release()
 
+        if self.perform():
+            return True
+
         num = 1
         while num != 0:
 
-            self._lock.acquire()
-            num, succeeded, failed = multi.info_read()
-            self._lock.release()
+            num, succeeded, failed = self._multi.info_read()
 
             self.changeActiveDownloads(-len(succeeded)-len(failed))
 
@@ -1501,9 +1513,7 @@
 
                 local.close()
 
-                self._lock.acquire()
-                multi.remove_handle(handle)
-                self._lock.release()
+                self.deactivate_handle(handle)
 
                 if handle.getinfo(pycurl.SIZE_DOWNLOAD) == 0:
                     # Not modified
@@ -1516,10 +1526,6 @@
                     if mtime != -1:
                         os.utime(localpath, (mtime, mtime))
 
-                del self._active[handle]
-                userhost = (url.user, url.host, url.port)
-                self._inactive[handle] = userhost
-
                 valid, reason = fetcher.validate(item, localpath,
                                                  withreason=True)
                 if valid:
@@ -1540,14 +1546,8 @@
 
                 local.close()
 
-                self._lock.acquire()
-                multi.remove_handle(handle)
-                self._lock.release()
+                self.deactivate_handle(handle)
 
-                del self._active[handle]
-                userhost = (url.user, url.host, url.port)
-                self._inactive[handle] = userhost
-
                 if handle.partsize and "byte ranges" in errmsg:
                     os.unlink(localpath+".part")
                     item.reset()
@@ -1652,25 +1652,10 @@
                             handle.setopt(pycurl.TIMECONDITION,
                                           pycurl.TIMECONDITION_NONE)
 
-                        self._lock.acquire()
-                        multi.add_handle(handle)
-                        self._lock.release()
+                        self._multi.add_handle(handle)
 
         return bool(self._queue or self._active)
 
-    def perform(self):
-        import pycurl
-        multi = self._multi
-        mp = pycurl.E_CALL_MULTI_PERFORM
-        while self._queue or self._active:
-            self._lock.acquire()
-            res = mp
-            while res == mp:
-                res, num = multi.perform()
-            self._lock.release()
-            time.sleep(0.2)
-        self._running = False
-
 try:
     import pycurl
 except ImportError: