set unlimited HWM for all relay devices

libzmq-3 set the default HWM for sockets to 1000 from infinite,
which can result in dropped messages on ROUTER or PUB sockets under high load.

IPython/parallel/apps/ipcontrollerapp.py

@@ -56,7 +56,7 b' from IPython.parallel.controller.hub import HubFactory'
 from IPython.parallel.controller.scheduler import TaskScheduler,launch_scheduler
 from IPython.parallel.controller.dictdb import DictDB
 
-from IPython.parallel.util import split_url, disambiguate_url
+from IPython.parallel.util import split_url, disambiguate_url, set_hwm
 
 # conditional import of SQLiteDB / MongoDB backend class
 real_dbs = []
@@ -385,6 +385,7 b' class IPControllerApp(BaseParallelApplication):'
 
         # Multiplexer Queue (in a Process)
         q = mq(zmq.ROUTER, zmq.ROUTER, zmq.PUB, b'in', b'out')
+        
         q.bind_in(f.client_url('mux'))
         q.setsockopt_in(zmq.IDENTITY, b'mux_in')
         q.bind_out(f.engine_url('mux'))
@@ -438,6 +439,22 b' class IPControllerApp(BaseParallelApplication):'
                 # single-threaded Controller
                 kwargs['in_thread'] = True
                 launch_scheduler(*sargs, **kwargs)
+        
+        # set unlimited HWM for all relay devices
+        if hasattr(zmq, 'SNDHWM'):
+            q = children[0]
+            q.setsockopt_in(zmq.RCVHWM, 0)
+            q.setsockopt_out(zmq.SNDHWM, 0)
+            
+            for q in children[1:]:
+                if not hasattr(q, 'setsockopt_in'):
+                    continue
+                q.setsockopt_in(zmq.SNDHWM, 0)
+                q.setsockopt_in(zmq.RCVHWM, 0)
+                q.setsockopt_out(zmq.SNDHWM, 0)
+                q.setsockopt_out(zmq.RCVHWM, 0)
+                q.setsockopt_mon(zmq.SNDHWM, 0)
+            
 
     def terminate_children(self):
         child_procs = []

IPython/parallel/controller/hub.py

@@ -285,6 +285,7 b' class HubFactory(RegistrationFactory):'
         
         # Registrar socket
         q = ZMQStream(ctx.socket(zmq.ROUTER), loop)
+        util.set_hwm(q, 0)
         q.bind(self.client_url('registration'))
         self.log.info("Hub listening on %s for registration.", self.client_url('registration'))
         if self.client_ip != self.engine_ip:
@@ -297,6 +298,7 b' class HubFactory(RegistrationFactory):'
         hpub = ctx.socket(zmq.PUB)
         hpub.bind(self.engine_url('hb_ping'))
         hrep = ctx.socket(zmq.ROUTER)
+        util.set_hwm(hrep, 0)
         hrep.bind(self.engine_url('hb_pong'))
         self.heartmonitor = HeartMonitor(loop=loop, config=self.config, log=self.log,
                                 pingstream=ZMQStream(hpub,loop),

IPython/parallel/controller/scheduler.py

@@ -811,13 +811,16 b' def launch_scheduler(in_addr, out_addr, mon_addr, not_addr, reg_addr, config=Non'
         ctx = zmq.Context()
         loop = ioloop.IOLoop()
     ins = ZMQStream(ctx.socket(zmq.ROUTER),loop)
+    util.set_hwm(ins, 0)
     ins.setsockopt(zmq.IDENTITY, identity + b'_in')
     ins.bind(in_addr)
 
     outs = ZMQStream(ctx.socket(zmq.ROUTER),loop)
+    util.set_hwm(outs, 0)
     outs.setsockopt(zmq.IDENTITY, identity + b'_out')
     outs.bind(out_addr)
     mons = zmqstream.ZMQStream(ctx.socket(zmq.PUB),loop)
+    util.set_hwm(mons, 0)
     mons.connect(mon_addr)
     nots = zmqstream.ZMQStream(ctx.socket(zmq.SUB),loop)
     nots.setsockopt(zmq.SUBSCRIBE, b'')

IPython/parallel/util.py

@@ -349,3 +349,20 b' def local_logger(logname, loglevel=logging.DEBUG):'
     logger.setLevel(loglevel)
     return logger
 
+def set_hwm(sock, hwm=0):
+    """set zmq High Water Mark on a socket
+    
+    in a way that always works for various pyzmq / libzmq versions.
+    """
+    import zmq
+    
+    for key in ('HWM', 'SNDHWM', 'RCVHWM'):
+        opt = getattr(zmq, key, None)
+        if opt is None:
+            continue
+        try:
+            sock.setsockopt(opt, hwm)
+        except zmq.ZMQError:
+            pass
+
+        
  No newline at end of file