Do I need to clean the completed tasks in tokio::task::JoinSet?

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hi, I'm writing a TUI executable, I use tokio::select on crossterm::event::EventStream to achieve a non-blocking loop to receive user keyboard/mouse events.

At the same time, I also want to create an async task queue that can run some generic tasks: read/write files, update data logic, delay/timeout methods.

The word task here is similar to function pointers with a global context in C/C++.

After I read some documents, I found rust and tokio provide the tokio::task::JoinSet, it could help me create new async tasks, and run them in multiple green threads. And also possible to abort all the tasks, or wait for them done.

That's probably what I want. But I still have 1 more question:

The JoinSet is not a future Stream, so I cannot use tokio::select on it. So how could I know what task is completed?

If I don't select it, but keep create new tasks. Will it increase memory usage along with the tasks created, and finally get out of memory and crash the TUI application?

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JoinSet keeps the result of running a task to completion available until you use join_all, join_next, or try_join_next to get the result of running a task. Memory usage will go up as long as this isn't done.

You have three directions you can go in:

  1. Use tokio_util::TaskTracker to track tasks. This is a lot like JoinSet, but it immediately drops the result of running a task, rather than keeping it around for later.
  2. Use tokio::select! on JoinSet::join_next as well as EventStream::next, to pull out completed tasks.
  3. Make use of futures::stream::poll_fn to turn JoinSet::poll_join_next into a stream
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Thanks @farnz , the 2nd option seems really fit my requirement! I will have a try!

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