Potential blocking issue when use tracing_unbounded channel to send Sender<T> #13849
Description
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Description of bug
In #13504, the underlying channel of tracing_unbounded channel switched from futures-channel to async-channel.
In async-channel, the unconsumed messages of the channel will not drop even though all the receivers have been dropped and these messages can never be accessed smol-rs/async-channel#23, this behavior may be an issue when using tracing_unbounded channel to send Sender<T> to another worker and wait for receiving from this Sender<T> (like the usage mentioned at smol-rs/async-channel#23).
In autonomys/subspace#1352 (comment), we have encountered an issue with the abovementioned usage which causes our test block forever. I'm not quite familiar with the tracing_unbounded usage in substrate, but I do observe some use cases that use tracing_unbounded channel to send Sender<T> and they may be potential issues:
substrate/client/peerset/src/lib.rs
Line 278 in 851a826
substrate/client/network/sync/src/engine.rs
Line 331 in 851a826