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Tmux is used to create, manage and kill virtual console sessions, which can be used for any purpose a console can take care of - in this case e.g. for starting (and stopping) your selected script. Tmux sessions always have a unique name by which they can be identified, e.g. middleware for the Middleware session. This is especially useful in case a tmux session could not be destroyed after a program crash: If a new session with the same name gets started from the LCC, the old session gets overridden.
The script that takes care of these sessions also writes command line outputs of the running programs into .../software/../lcc_script_logs. For example, the script to start and run the middleware is called tmux_middleware.bash and can be found in lab_control_center/bash. If you want to find out why your program crashed, the contents of this folder might be useful, in addition to log messages in the system and other custom error reports. You can find this folder for remote deployment as well (on the NUCs).
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Tasks with a limited runtime are managed using fork and the resulting PID, e.g. for sending reboot commands to the vehicles. These tasks are not observed by the crash checker, as they are not strictly part of a running simulation and are not supposed to be always online. Tmux offers a more convenient way to manage tasks, to detach them from the LCC and to observe if they are still online, and is thus used for any simulation-related externally started program (User-provided script, Middleware, IPsIPS...) |
Sessions exist for the middleware Middleware and your script (if a locally running simulation was started and a valid script was selected). There also exist sessions for the labcam, position detection and other vital features of the LCC (if they are activated).
The integrated crash checker checks regularly - during a simulation - if all these tools are still running. To simplify the process, we only look up if the according tmux sessions existexists, which in most cases is enough to detect a crash of the contained program.
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Remote Deployment
Take a look at this page. The crash checker also monitors running tmux sessions on the NUCs, if they have been deployed and the simulation is still running.
Round Trip Time (RTT) Measurements
Functionality
The round trip time is a measurement for the time (here: in milliseconds) a direct message exchange with instant answers takes between two participants within the network. It may differ with network load or may even produce no results in case of serious connection problems. Thus, regular RTT measurements provide a simple metric for the current quality of the connection to participants in the network and its stability.
The LCC regularly sends RTT measurement requests as long as no simulation is running (to prevent network overload).
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Picture of the LCC monitoring bar including information about the RTT, when no measurements could be made (because the participants are offline).
TODO: Insert image with example for working RTT measurement.
Experiment Runtime
A small indicator has been added that shows the user how long the experiment has been running. It is also part of the monitoring bar. It displays hours, minutes and seconds (if they are greater than zero).
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Overview
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