diff --git a/src/calibre/gui2/tweak_book/completion/__init__.py b/src/calibre/gui2/tweak_book/completion/__init__.py
new file mode 100644
index 0000000000..8b13789179
--- /dev/null
+++ b/src/calibre/gui2/tweak_book/completion/__init__.py
@@ -0,0 +1 @@
+
diff --git a/src/calibre/gui2/tweak_book/completion/worker.py b/src/calibre/gui2/tweak_book/completion/worker.py
new file mode 100644
index 0000000000..e05e8ebd8b
--- /dev/null
+++ b/src/calibre/gui2/tweak_book/completion/worker.py
@@ -0,0 +1,102 @@
+#!/usr/bin/env python
+# vim:fileencoding=utf-8
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__ = 'GPL v3'
+__copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
+
+import cPickle, os, sys
+from threading import Thread, Event
+from Queue import Queue
+from contextlib import closing
+
+from calibre.constants import iswindows
+from calibre.utils.ipc import eintr_retry_call
+
+class CompletionWorker(Thread):
+
+    daemon = True
+
+    def __init__(self, worker_entry_point='main'):
+        Thread.__init__(self)
+        self.worker_entry_point = worker_entry_point
+        self.start()
+        self.main_queue = Queue()
+        self.reap_thread = None
+        self.shutting_down = False
+        self.connected = Event()
+
+    def launch_worker_process(self):
+        from calibre.utils.ipc.server import create_listener
+        from calibre.utils.ipc.simple_worker import start_pipe_worker
+        self.worker_process = p = start_pipe_worker(
+            'from {0} import run_main, {1}; run_main({1})'.format(self.__class__.__module__, self.worker_entry_point), stdout=None)
+        auth_key = os.urandom(32)
+        address, self.listener = create_listener(auth_key)
+        eintr_retry_call(p.stdin.write, cPickle.dumps((address, auth_key), -1))
+        p.stdin.flush(), p.stdin.close()
+        self.control_conn = eintr_retry_call(self.listener.accept)
+        self.data_conn = eintr_retry_call(self.listener.accept)
+        self.connected.set()
+
+    def send(self, data, conn=None):
+        conn = conn or self.control_conn
+        try:
+            eintr_retry_call(conn.send, data)
+        except:
+            if not self.shutting_down:
+                raise
+
+    def recv(self, conn=None):
+        conn = conn or self.control_conn
+        try:
+            return eintr_retry_call(conn.recv)
+        except:
+            if not self.shutting_down:
+                raise
+
+    def wait_for_connection(self, timeout=None):
+        self.connected.wait(timeout)
+
+    def run(self):
+        self.launch_worker_process()
+        while True:
+            obj = self.main_queue.get()
+            if obj is None:
+                break
+
+    def shutdown(self):
+        self.shutting_down = True
+        self.main_queue.put(None)
+        p = self.worker_process
+        if p.returncode is None:
+            self.worker_process.terminate()
+            t = self.reap_thread = Thread(target=p.wait)
+            t.daemon = True
+            t.start()
+
+    def join(self, timeout=0.2):
+        if self.reap_thread is not None:
+            self.reap_thread.join(timeout)
+        if not iswindows and self.worker_process.returncode is None:
+            self.worker_process.kill()
+        return self.worker_process.returncode
+
+
+def run_main(func):
+    from multiprocessing.connection import Client
+    address, key = cPickle.loads(eintr_retry_call(sys.stdin.read))
+    with closing(Client(address, authkey=key)) as control_conn, closing(Client(address, authkey=key)) as data_conn:
+        func(control_conn, data_conn)
+
+def test_main(control_conn, data_conn):
+    obj = control_conn.recv()
+    control_conn.send(obj)
+
+def test():
+    w = CompletionWorker(worker_entry_point='test_main')
+    w.wait_for_connection()
+    w.send('Hello World!')
+    print (w.recv())
+    w.shutdown(), w.join()
diff --git a/src/calibre/utils/ipc/simple_worker.py b/src/calibre/utils/ipc/simple_worker.py
index d06550cdce..0a0e0cbcaf 100644
--- a/src/calibre/utils/ipc/simple_worker.py
+++ b/src/calibre/utils/ipc/simple_worker.py
@@ -134,11 +134,12 @@ def create_worker(env, priority='normal', cwd=None, func='main'):
     w(cwd=cwd, priority=priority)
     return listener, w
 
-def start_pipe_worker(command, env=None, priority='normal'):
-    import subprocess, atexit
+def start_pipe_worker(command, env=None, priority='normal', **process_args):
+    import subprocess
     from functools import partial
     w = Worker(env or {})
     args = {'stdout':subprocess.PIPE, 'stdin':subprocess.PIPE, 'env':w.env}
+    args.update(process_args)
     if iswindows:
         import win32process
         priority = {
@@ -157,7 +158,6 @@ def start_pipe_worker(command, env=None, priority='normal'):
         args['close_fds'] = True
 
     p = subprocess.Popen([w.executable, '--pipe-worker', command], **args)
-    atexit.register(w.kill)
     return p
 
 def fork_job(mod_name, func_name, args=(), kwargs={}, timeout=300,  # seconds
diff --git a/src/calibre/utils/ipc/worker.py b/src/calibre/utils/ipc/worker.py
index cc4a2a73fa..28371d8000 100644
--- a/src/calibre/utils/ipc/worker.py
+++ b/src/calibre/utils/ipc/worker.py
@@ -162,7 +162,7 @@ def main():
         # Close open file descriptors inherited from parent
         # On Unix this is done by the subprocess module
         os.closerange(3, 256)
-    if isosx and 'CALIBRE_WORKER_ADDRESS' not in os.environ:
+    if isosx and 'CALIBRE_WORKER_ADDRESS' not in os.environ and '--pipe-worker' not in sys.argv:
         # On some OS X computers launchd apparently tries to
         # launch the last run process from the bundle
         # so launch the gui as usual