Hi Tom, after having a short look at the code again, I can confirm that the traci python client is probably not ready to be used for multiple connections, especially when using subscriptions. Encapsulating the global variables in an object seems to be a good idea although I do not want to force everyone to include that object in every call because it would break all the existing code. So either we should include it only in those cases where it is really needed (subscriptions), or, what I like more, extend the existing global traci._connections to not only include the real socket connections but rather a TraCI object as proposed by you and switch between them with the already existing traci.switch command.
A prototype implementation would be very welcome! Best regards, Michael Am 08.07.2014 21:41, schrieb Thomas Lockhart: > On 7/8/14 12:05 PM, Michael Behrisch wrote: >> Hi Tom, >> >> Am 05.07.2014 04:51, schrieb Thomas Lockhart: >>> I'm looking at the city_mobil runner.py and afaict it is having trouble >>> with the non-reentrant structure of the traci module. It does one run of >>> simpleManager.py and then tries to do the same thing with >>> activeManager.py. There are some problems with global variables in >>> vehicleControl.py and in statistics.py, and even after cleaning those up >>> it seems that traci has some additional globals which are not >>> initialized in the traci.init() call or reset in the traci.close() call. >>> >>> Any thoughts on whether this is a priority to fix in traci, or whether >>> we should restructure the runner script to ensure that the two test >>> cases are run in separate processes? >> I would say fixing the CityMobil scenario is not so high priority >> because the way the runner does it is not the usual use case, you would >> probably only start one manager. >> But I would say traci itself should be clean after the connection(s) are >> closed. Can you give an example on what goes wrong? >> > What I see is that the second instantiation ends immediately at step > zero with a message to the effect "at the request of TraCI". If I go > through and re-initialize some more of the globals defined in > traci/__init__.py, I can get it to end at 100 steps, which is an > explicit completion condition in the manager if the number of persons is > zero. But the expected behavior is that it runs for 3k or 4k steps, > which is what happens when that test case is run separately. > > There must be more globals which need to be re-initialized, but I > haven't found them all yet. > > In general, traci is implemented as a set of functions and module-wide > state variables, which means that there are variables which can not be > shared between traci connections without exposing side effects. If this > were implemented as a class then the state and temporary variables would > be encapsulated in the object and would be created anew when a new > object was created. > > If this were desirable I would guess that this could be implemented as > an addition to the current features. Something like: > > from traci import traci as TraCI > traci = TraCI() > traci.init(PORT) > # or traci = TraCI(PORT) > ... > > where I've made the code a bit obtuse to show how it could almost match > the current usage. > > The module could possibly still allow the current usage: > > import traci > traci.init(PORT) > ... > > possibly by implementing the init() function in the traci/__init__.py > file as > > tglobal = None > ... > def init(PORT): > tglobal = traci(PORT) > return > > Let me know if a prototype implementation would be of interest. > > - Tom ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ sumo-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/sumo-user
