BUG REPORT: SUMO simulation stops unexpectedly during long simulations with Simu5G and Veins

[enzoniko]

Description: When running long-duration simulations with Simu5G, Veins, SUMO, Omnet++, and INET, the SUMO simulation stops abruptly without any error message. This happens consistently in both the Simu5G PnP VM and a local installation, across various scenarios and network configurations. The Omnet++ simulation continues, but no new vehicles are spawned in SUMO, effectively halting the vehicular network simulation and preventing data collection.
Steps to Reproduce:
*Set up simulation: Use the Simu5G PnP VM or follow the local installation instructions detailed below.
*Scenario: Employ any scenario with continuous traffic patterns and a longer duration (exceeding 1 hour for instance). The LuSTNanoScenario from the F2MD repository reliably reproduces this issue.
*Modify simulation: Change the “cars” examples (both LTE and 5G NR) to use the lust.launchd.xml file, making sure to have all the necessary scenario files in the directory. These files can be found here. Also, remember to modify the simulation so the “sim_time_limit” is higher.
*Run simulation: Initiate the simulation and observe.
Expected Result: The simulation should run continuously for the entire duration specified in the scenario, with SUMO and Omnet++ working in sync.
Actual Result: The SUMO simulation stops prematurely without any error message, while the Omnet++ simulation continues. This prevents new vehicles from being generated, hindering the simulation of the vehicular network.
Observations:
The issue appears to occur during breaks in vehicle spawning when no vehicles are visible on the SUMO GUI.
Introducing a stationary vehicle parked for the entire simulation in the LuSTNanoScenario (as described in the attached report) serves as a temporary workaround, but this may not be a general solution and could affect the realism of the simulation.
System Information:
*Simu5G version: 1.2.1
*Veins version: 5.2
*SUMO version: 1.11.0
*Omnet++ version: 6.0.3
*INET version: 4.4
*Operating System: Ubuntu 20.04 (PnP) or Ubuntu 22.04 (Local installation)
*Simulation duration: Longer (1 hour for instance)
Possible Workarounds:
Adding a permanently parked vehicle to the simulation scenario (as detailed in the attached report). This workaround is not ideal as it may introduce artificial behavior and impact the validity of the simulation results.
Severity: High - This bug severely limits the ability to conduct realistic long-term simulations with Simu5G and Veins, preventing the collection of meaningful network traces and hindering research objectives.

Local Installation Instructions
To set up a local installation, the following steps were followed:

Workspace Setup
*Create a workspace directory: /home/workspace.

Download Required Components
*Omnet++ 6.0 following official instructions.
*SUMO 1.11.0 from SUMO documentation and add it to the system PATH.
*Veins 5.2 extracted to /home/workspace/simu5GWS.
*Simu5G 1.2.1 from GitHub extracted to /home/workspace/simu5GWS and renamed to "simu5G".

Set Up Omnet++ Projects
*Open the Omnet++ IDE on the /home/workspace/simu5GWS.
*Install INET 4.4 through the menu: Help -> Install Simulation Models.
*Import Veins, INET, and Simu5G projects via File -> Import -> General -> Existing Projects into Workspace.
*Configure project references:
**Veins_INET → Reference INET 4.4.
**Simu5G → Reference Veins_INET but not Veins.
*Enable Simu5G features: Project Properties -> Omnet++ -> Project Features → Tick "Simu5G Cars".
*Build all projects ( Ctrl + B ).

Validation
Run the cars example in both LTE and NR folders (Simu5G/simulations) while ensuring the veins_launchd daemon is active.

[paulojna]

I have encountered the same problem. For the same .net and .rou files, vehicles stop being injected depending on the SUMO scale parameter (for example, with scale=0.3, it stops at ~14 000 seconds while with scale=0.2 it stops at ~11 000 seconds). This suggests the issue might be related to the number of vehicles in the simulation (?)