[SPARK-41460][CORE] Introduce IsolatedThreadSafeRpcEndpoint to extend IsolatedRpcEndpoint
#38995
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I think this would breach the original design by the author argued at #26059 (comment). I don't want to break it, though I also don't have a use case of |
| /** | ||
| * Limit the threadCount to 1 so that messages are ensured to be handled in a thread-safe way. | ||
| */ | ||
| final def threadCount(): Int = 1 |
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According to the PR description, this final def is the main contribution, @Ngone51 ?
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Yes, and also the naming of IsolatedThreadSafeRpcEndpoint.
dongjoon-hyun
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IsolatedThreadSafeRpcEndpoint to extend IsolatedRpcEndpoint
mridulm
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Dec 10, 2022
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Looks good to me.
With this change, IsolatedRpcEndpoint is essentially a noop - other than as a marker interface, right ? Wondering if we want to remove it entirely
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Thanks @dongjoon-hyun @mridulm |
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…nd `IsolatedRpcEndpoint` ### What changes were proposed in this pull request? This PR introduces a new layer `IsolatedThreadSafeRpcEndpoint` to extend `IsolatedRpcEndpoint` and changes all the endpoints which currently extend `IsolatedRpcEndpoint` to extend `IsolatedThreadSafeRpcEndpoint` instead. Besides, `IsolatedThreadSafeRpcEndpoint` has overridden `def threadCount(): Int = 1` with `final` to avoid mistakenly having thread count > 1 for the thread-safe endpoint. ### Why are the changes needed? Busy endpoints like `DriverEndpoint`, `BlockManagerMasterEndpoint` were known to be thread-safe when they extended `ThreadSafeRpcEndpoint`. After we introduce `IsolatedRpcEndpoint` in [SPARK-29398](https://issues.apache.org/jira/browse/SPARK-29398), all these busy endpoints have been changed to extend `IsolatedRpcEndpoint`. These busy endpoints are still thread-safe since `IsolatedRpcEndpoint` by default only uses 1 thread. But that's not explicit to developers now compared to `ThreadSafeRpcEndpoint` (I actually find some people became to be confused about whether the endpoint is thread-safe or not). From time to time, `IsolatedRpcEndpoint#threadCount` might be mistakenly overridden with threadCount > 1 leading to thread-safety being broken. So this PR refactor here a bit to avoid the potential issue. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? N/A Closes apache#38995 from Ngone51/isolated. Authored-by: Yi Wu <yi.wu@databricks.com> Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
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What changes were proposed in this pull request?
This PR introduces a new layer
IsolatedThreadSafeRpcEndpointto extendIsolatedRpcEndpointand changes all the endpoints which currently extendIsolatedRpcEndpointto extendIsolatedThreadSafeRpcEndpointinstead. Besides,IsolatedThreadSafeRpcEndpointhas overriddendef threadCount(): Int = 1withfinalto avoid mistakenly having thread count > 1 for the thread-safe endpoint.Why are the changes needed?
Busy endpoints like
DriverEndpoint,BlockManagerMasterEndpointwere known to be thread-safe when they extendedThreadSafeRpcEndpoint. After we introduceIsolatedRpcEndpointin SPARK-29398, all these busy endpoints have been changed to extendIsolatedRpcEndpoint. These busy endpoints are still thread-safe sinceIsolatedRpcEndpointby default only uses 1 thread. But that's not explicit to developers now compared toThreadSafeRpcEndpoint(I actually find some people became to be confused about whether the endpoint is thread-safe or not). From time to time,IsolatedRpcEndpoint#threadCountmight be mistakenly overridden with threadCount > 1 leading to thread-safety being broken. So this PR refactor here a bit to avoid the potential issue.Does this PR introduce any user-facing change?
No.
How was this patch tested?
N/A