Implement exclude keys for ActionController::Live execution sharing #56393
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When using `ActionController::Live` the execution context is shared across threads. In some cases, like database context switching from a writer to a replica connection, you may not want that context to be shared. This PR implements a config option for excluding specific keys from the shared execution. By default no keys are shared to support backwards compatibility in order to maintain current behavior while implementing a way for applications experiencing an issue with database connections to opt-out. See #52906. To exclude a specific key application-wide, set the following config option: ```ruby config.action_controller.live_streaming_excluded_keys = [:active_record_connected_to_stack] ``` If you want finer-grained control over which controllers exclude these keys you can set `live_streaming_excluded_keys` in the controller itself. ```ruby class MyController < ApplicationController include ActionController::Live self.live_streaming_excluded_keys = [:active_record_connected_to_stack] def index ... end end ``` In the future we may want to default to excluding this key since I'm not sure anyone wants to share database context. However I chose not to do that in this PR because we need to backport this to use as a bug fix, and if it changes behavior that could break applications. Fixes #52906
eileencodes
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Implement exclude keys for ActionController::Live execution sharing
eileencodes
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Implement exclude keys for ActionController::Live execution sharing
tavianator
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Dec 18, 2025
| # shares execution state from the parent thread. | ||
| # | ||
| # You can configure which execution state keys should be excluded from being shared | ||
| # using the `config.action_controller.live.streaming_excluded_keys` configuration: |
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| # using the `config.action_controller.live.streaming_excluded_keys` configuration: | |
| # using the `config.action_controller.live_streaming_excluded_keys` configuration: |
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When using
ActionController::Livethe execution context is shared across threads. In some cases, like database context switching from a writer to a replica connection, you may not want that context to be shared.This PR implements a config option for excluding specific keys from the shared execution. By default no keys are shared to support backwards compatibility in order to maintain current behavior while implementing a way for applications experiencing an issue with database connections to opt-out. See #52906.
To exclude a specific key application-wide, set the following config option:
If you want finer-grained control over which controllers exclude these keys you can set
live_streaming_excluded_keysin the controller itself.In the future we may want to default to excluding this key since I'm not sure anyone wants to share database context. However I chose not to do that in this PR because we need to backport this to use as a bug fix, and if it changes behavior that could break applications.
Fixes #52906