diff --git a/eventlet/hubs/poll.py b/eventlet/hubs/poll.py
index 8bc99b8..d6c62ca 100644
--- a/eventlet/hubs/poll.py
+++ b/eventlet/hubs/poll.py
@@ -5,7 +5,7 @@ select = patcher.original('select')
 time = patcher.original('time')
 sleep = time.sleep
 
-from eventlet.common import get_errno
+from eventlet.common import get_errno, clear_sys_exc_info
 from eventlet.hubs.hub import BaseHub, READ, WRITE
 
 EXC_MASK = select.POLLERR | select.POLLHUP
@@ -109,4 +109,4 @@ class Hub(BaseHub):
                 raise
             except:
                 self.squelch_exception(fileno, sys.exc_info())
-                sys.exc_clear()
+                clear_sys_exc_info()
diff --git a/eventlet/hubs/timer.py b/eventlet/hubs/timer.py
index e4c185e..e99cd28 100644
--- a/eventlet/hubs/timer.py
+++ b/eventlet/hubs/timer.py
@@ -75,6 +75,11 @@ class Timer(object):
         except AttributeError:
             pass
 
+    # No default ordering in 3.x. heapq uses <
+    # FIXME should full set be added?
+    def __lt__(self, other): 
+        return id(self)<id(other)
+
 class LocalTimer(Timer):
 
     def __init__(self, *args, **kwargs):
diff --git a/eventlet/proc.py b/eventlet/proc.py
index 6b65bc0..0ecc3f5 100644
--- a/eventlet/proc.py
+++ b/eventlet/proc.py
@@ -389,7 +389,7 @@ class Source(object):
             return LinkToGreenlet(listener)
         if hasattr(listener, 'send'):
             return LinkToEvent(listener)
-        elif callable(listener):
+        elif hasattr(listener, '__call__'):
             return LinkToCallable(listener)
         else:
             raise TypeError("Don't know how to link to %r" % (listener, ))
diff --git a/eventlet/tpool.py b/eventlet/tpool.py
index 9c35ffc..50d631f 100644
--- a/eventlet/tpool.py
+++ b/eventlet/tpool.py
@@ -30,8 +30,10 @@ QUIET=True
 
 _rfile = _wfile = None
 
+_bytetosend = ' '.encode()
+
 def _signal_t2e():
-    _wfile.write(' ')
+    _wfile.write(_bytetosend)
     _wfile.flush()
 
 _reqq = None
@@ -42,7 +44,7 @@ def tpool_trampoline():
     while(True):
         try:
             _c = _rfile.read(1)
-            assert _c != ""
+            assert _c
         except ValueError:
             break  # will be raised when pipe is closed
         while not _rspq.empty():
@@ -218,8 +220,8 @@ def setup():
         _setup_already = True
     try:
         _rpipe, _wpipe = os.pipe()
-        _wfile = os.fdopen(_wpipe,"w",0)
-        _rfile = os.fdopen(_rpipe,"r",0)
+        _wfile = os.fdopen(_wpipe,"wb",0)
+        _rfile = os.fdopen(_rpipe,"rb",0)
         ## Work whether or not wrap_pipe_with_coroutine_pipe was called
         if not isinstance(_rfile, greenio.GreenPipe):
             _rfile = greenio.GreenPipe(_rfile)
@@ -234,8 +236,8 @@ def setup():
         csock = util.__original_socket__(socket.AF_INET, socket.SOCK_STREAM)
         csock.connect(('localhost', sock.getsockname()[1]))
         nsock, addr = sock.accept()
-        _rfile = greenio.GreenSocket(csock).makefile()
-        _wfile = nsock.makefile('w')
+        _rfile = greenio.GreenSocket(csock).makefile('rb', 0)
+        _wfile = nsock.makefile('wb',0)
 
     _reqq = Queue(maxsize=-1)
     _rspq = Queue(maxsize=-1)
diff --git a/tests/convenience_test.py b/tests/convenience_test.py
index ca561d9..a3be65f 100644
--- a/tests/convenience_test.py
+++ b/tests/convenience_test.py
@@ -1,6 +1,6 @@
 import eventlet
 from eventlet import event
-from tests import LimitedTestCase
+from tests import LimitedTestCase, s2b
 
 class TestServe(LimitedTestCase):
     def setUp(self):
@@ -21,37 +21,37 @@ class TestServe(LimitedTestCase):
         l = eventlet.listen(('localhost', 0))
         gt = eventlet.spawn(eventlet.serve, l, closer)
         client = eventlet.connect(('localhost', l.getsockname()[1]))
-        client.sendall('a')
-        self.assertEqual('', client.recv(100))
+        client.sendall(s2b('a'))
+        self.assertFalse(client.recv(100))
         gt.kill()
 
 
     def test_excepting_server(self):
         # tests that the server closes the client sock on handle() exception
         def crasher(sock,addr):
-            x = sock.recv(1024)
+            sock.recv(1024)
             0/0
             
         l = eventlet.listen(('localhost', 0))
         gt = eventlet.spawn(eventlet.serve, l, crasher)
         client = eventlet.connect(('localhost', l.getsockname()[1]))
-        client.sendall('a')
+        client.sendall(s2b('a'))
         self.assertRaises(ZeroDivisionError, gt.wait)
-        self.assertEqual('', client.recv(100))
+        self.assertFalse(client.recv(100))
 
     def test_excepting_server_already_closed(self):
         # same as above but with explicit clsoe before crash
         def crasher(sock,addr):
-            x = sock.recv(1024)
+            sock.recv(1024)
             sock.close()
             0/0
             
         l = eventlet.listen(('localhost', 0))
         gt = eventlet.spawn(eventlet.serve, l, crasher)
         client = eventlet.connect(('localhost', l.getsockname()[1]))
-        client.sendall('a')
+        client.sendall(s2b('a'))
         self.assertRaises(ZeroDivisionError, gt.wait)
-        self.assertEqual('', client.recv(100))
+        self.assertFalse(client.recv(100))
 
     def test_called_for_each_connection(self):
         hits = [0]
@@ -61,7 +61,7 @@ class TestServe(LimitedTestCase):
         gt = eventlet.spawn(eventlet.serve, l, counter)
         for i in xrange(100):
             client = eventlet.connect(('localhost', l.getsockname()[1]))
-            self.assertEqual('', client.recv(100))            
+            self.assertFalse(client.recv(100))            
         gt.kill()
         self.assertEqual(100, hits[0])
         
@@ -85,14 +85,14 @@ class TestServe(LimitedTestCase):
     def test_concurrency(self):
         evt = event.Event()
         def waiter(sock, addr):
-            sock.sendall('hi')
+            sock.sendall(s2b('hi'))
             evt.wait()
         l = eventlet.listen(('localhost', 0))
         gt = eventlet.spawn(eventlet.serve, l, waiter, 5)
         def test_client():
             c = eventlet.connect(('localhost', l.getsockname()[1]))
             # verify the client is connected by getting data
-            self.assertEquals('hi', c.recv(2))
+            self.assertEquals(s2b('hi'), c.recv(2))
             return c
         clients = [test_client() for i in xrange(5)]
         # very next client should not get anything
@@ -101,5 +101,3 @@ class TestServe(LimitedTestCase):
             timeout_value="timed out")
         self.assertEquals(x, "timed out")
 
-        
-        
\ No newline at end of file