yjshen commented on a change in pull request #811:
URL: https://github.com/apache/arrow-datafusion/pull/811#discussion_r692659385
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File path: datafusion/Cargo.toml
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@@ -56,9 +56,9 @@ paste = "^1.0"
num_cpus = "1.13.0"
chrono = "0.4"
async-trait = "0.1.41"
-futures = "0.3"
+futures = { version = "0.3", features = ["executor"] }
Review comment:
While using `tokio::runtime::Handle::block_on`, I'm facing with:
> ’Cannot start a runtime from within a runtime. This happens because a
function (like `block_on`) attempted to block the current thread while the
thread is being used to drive asynchronous tasks.
Since `block_on` is `try_enter`ing an already entered runtime, therefore I
changed to `future::executor`'s to avoid panic in the first place. But as I
noted before, `future::executor::block_on` is also flawed here:
> However, this approach is flawed for block_on may block the only thread in
tokio, and the future inside won't get a chance to run, therefore hanging
forever if the tokio runtime is not a multi-threaded one. (I temporarily change
the related test to use #[tokio::test(flavor = "multi_thread", worker_threads =
2)] to avoid hanging).
Do you have any suggestions on this?
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