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fix(frontend): use dedicated runtime to accept connection #16838

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merged 2 commits into from
May 21, 2024

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@chenzl25 chenzl25 commented May 20, 2024

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What's changed and what's your intention?

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@chenzl25 chenzl25 requested review from BugenZhao and neverchanje May 20, 2024 10:57
@github-actions github-actions bot added the type/fix Bug fix label May 20, 2024
@chenzl25 chenzl25 requested a review from fuyufjh May 20, 2024 10:58
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LGTM

It might still be worth noting that if all threads in worker_runtime are occupied with CPU-intensive queries, even if new connections can be accepted, they can't make any progress.

This could be significant in Cloud free-tier deployment where there's only 1 CPU core thus 1 worker threads.

Can refer to #9019 and #16693.

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LGTM

It might still be worth noting that if all threads in worker_runtime are occupied with CPU-intensive queries, even if new connections can be accepted, they can't make any progress.

This could be significant in Cloud free-tier deployment where there's only 1 CPU core thus 1 worker threads.

Can refer to #9019 and #16693.

One thing I can't figure out is why using the same tokio runtime would block the listen.accept with 100% probability.

Arc::new(peer_addr),
));
}
let worker_runtime = tokio::runtime::Handle::current();
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@wangrunji0408 madsim-tokio seems doesn't contain tokio::runtime::Handle

error[E0433]: failed to resolve: could not find `Handle` in `runtime`
   --> src/utils/pgwire/src/pg_server.rs:258:42
    |
258 |     let worker_runtime = tokio::runtime::Handle::current();
    |                                          ^^^^^^ could not find `Handle` in `runtime`

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One thing I can't figure out is why using the same tokio runtime would block the listen.accept with 100% probability.

I guess there's some sense of affinity mechanism for the I/O driver, as described in #9019

since tokio tends to move the IO scheduler to the same worker thread with this session, and an infinite loop starves the IO scheduler so that the main thread listening to the connection cannot be woken again! 😨

Can also refer to tokio-rs/tokio#4730.

@chenzl25 chenzl25 enabled auto-merge May 21, 2024 05:43
@chenzl25 chenzl25 added this pull request to the merge queue May 21, 2024
Merged via the queue into main with commit fb88b6d May 21, 2024
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@chenzl25 chenzl25 deleted the dylan/use_dedicated_runtime_to_accept_connection branch May 21, 2024 07:08
github-merge-queue bot pushed a commit that referenced this pull request May 21, 2024
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Bug: Frontend hangs and can't accept new connection
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