Avoid a deadlock updating the network D-Bus tree #966
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Updating the tree must be done in a separate task. Otherwise, it could fight with an incoming request for the ObjectServer mutex, blocking the actions dispatching.
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Problem
If the network service receives an
Applyat the same time as any other request, it may get blocked.Solution
Updating the tree must be done in a separate task. Otherwise, it could fight with an incoming request for the ObjectServer mutex, blocking the actions dispatching.
Using tokio-console
I decided to use tokio-console to make it easier to find the problem. This tool collects and displays information about the asynchronous tasks in your program. In the screenshot below you can see that the D-Bus
Setdispatchers are blocked.Once you find the problem, it is kind of "obvious", but it may take some time until you figure out what is happening.
To use
tokio-consoleyou need to add some instrumentation to your program and, at this point, it implies adding some unstable Tokio APIs. So if you want to give it a try, you can try the code in the tokio-console branch.