Module pollcatch 

To emit tokio.PollCatchV1 events, you can set up the task hooks when setting up your Tokio runtime:

Then, you can use the decoder (look at the crate README) to find long polls in your program.

Use it around your main like this:

let mut rt: tokio::runtime::Builder = tokio::runtime::Builder::new_multi_thread();
rt.enable_all();

#[cfg(tokio_unstable)]
{
    rt.on_before_task_poll(|_| async_profiler_agent::pollcatch::before_poll_hook())
     .on_after_task_poll(|_| async_profiler_agent::pollcatch::after_poll_hook());
}
let rt = rt.build().unwrap();
rt.block_on(your_main())

Except on a poll that is involved in a profiling sample, the poll hook overhead is limited to a few thread-local accesses and should be very very fast.

When a profiling sample is taken (normally around 1 / second), it adds slightly more overhead to report the sample, but that is a matter of microseconds and therefore should not worsen tail latency problems.

Functions

after_poll_hook

Call this in the Tokio after task hook

before_poll_hook

Call this in the Tokio before task hook