Emulab experiments support a limited number of agents
Because of the way our event libraries construct subscriptions for pubsub, we appear to be limited to around 100 agents per node (or maybe it is per experiment). The size of the subscription string eventually exceeds the max size of a pubsub packet (4K) triggering:
event_subscribe_auth: could not subscribe to event
( EXPT == "testbed/lots-o-pagents" ) && ( OBJTYPE == "PROGRAM" ) &&
( OBJNAME == "atest-99" || OBJNAME == "atest-98" || OBJNAME == "atest-97" || OBJNAME == "atest-96" ||
OBJNAME == "atest-95" || OBJNAME == "atest-94" || OBJNAME == "atest-93" ||
...
OBJNAME == "atest-10" || OBJNAME == "atest-1" ) &&
( EVENTTYPE == "RUN" || EVENTTYPE == "START" || EVENTTYPE == "STOP" || EVENTTYPE == "HALT" || EVENTTYPE == "KILL" ) &&
SCHEDULER == 0 : PubSub Error:7 - pubsub_add_subscription: expression too big
could not subscribe to event
Lots of ways we might get around this, including registering multiple subscriptions and/or raising the size of a pubsub packet.