s2n-quic-dc stream::tests::restart test flakiness

[boquan-fang]

Security issue notifications

Problem:

s2n-quic CI introduce dcQUIC stream tokio tests in recent days. The PR #2772 implements those tests. However, the stream::tests::restart test is very flaky on macOS-latest platform. We need to address the flakiness.

Need By Date:

Soon.

Solution:

N/A. Need investigation.

Requirements / Acceptance Criteria:

The s2n-quic CI shouldn't be flaky on that test.

Out of scope:

The test running on aarch64-unknown-linux-gnu is running extremely slow. We need to address that problem as well, but that is not in scope with this issue.

[boquan-fang]

Pulling the Github MacOS-latest image down involves licensing issue which we can't do. Alternatively, we might try to use https://github.com/nektos/act to run the image locally? I hope that can provide faster feedback.

[boquan-fang]

Alternatively, I tried to start lots of CI runs with stream restart test only on my fork's main branch. There is no flakiness there: https://github.com/boquan-fang/s2n-quic/actions/workflows/ci.yml.

[boquan-fang]

My theory is that 50 milliseconds are not enough to reestablish a recovery handshake. I want to extend it to 2 seconds and see if that mitigate the flakiness.

[boquan-fang]

We primarily witness the flakiness of the restart test to be with UDP, but not TCP. I discussed this issue with @Mark-Simulacrum and we decided to disable the restart test with TCP on MacOS. We can come back to this ticket in the future. I am going to lower the priority of this ticket to low, since the flakiness has been largely addressed right now.