RFC 2: Skeleton for ExecutionContext #15350
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straight-shoota merged 16 commits intocrystal-lang:masterfrom Feb 22, 2025
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RFC 2: Skeleton for ExecutionContext #15350straight-shoota merged 16 commits intocrystal-lang:masterfrom
straight-shoota merged 16 commits intocrystal-lang:masterfrom
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- Add the `ExecutionContext` module; - Add the `ExecutionContext::Scheduler` module; - Add the `execution_context` compile-time flag. When the `execution_context` flag is set: - Don't load `Crystal::Scheduler`; - Plug `ExecutionContext` instead of `Crystal::Scheduler` in `spawn`, `Fiber`, ... This is only the skeleton: there are no implementations (yet). Trying to compile anything with `-Dexecution_context` will obviously fail for the time being.
The current ST and MT schedulers use a distinct pool per thread, which means we only need the thread safety for execution contexts that will share a single pool for a whole context.
The point is to avoid parallel enqueues while running the event loop, so we get better control to where and how the runnable fibers are enqueued; for example all at once instead of one by one (may not be as effective as it sounds). More importantly for Execution Contexts: it avoids parallel enqueues while the eventloop is running which sometimes leads to confusing behavior; for example when deciding to wake up a scheduler/thread we musn't interryupt the event loop (obviously). This is working correctly for the Polling (Epoll, Kqueue) and IOCP event loop implementations. I'm less confident with the libevent one where the external library executes arbitrary callbacks.
Co-authored-by: Johannes Müller <straightshoota@gmail.com>
We need this because we don't load crystal/scheduler anymore when execution contexts are enabled.
straight-shoota
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Jan 31, 2025
straight-shoota
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Merged with master to bring in #15409 + solved conflicts. |
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I solved more conflicts. Now I can run my branch with the ST and MT schedulers using #15345 and this branch 👍 |
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As far as I can tell: there's nothing left to do here. Just waiting for a (final) review :) |
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straight-shoota
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Integrates the skeleton as per crystal-lang/rfcs#2 - Add the `ExecutionContext` module; - Add the `ExecutionContext::Scheduler` module; - Add the `execution_context` compile-time flag. When the `execution_context` flag is set: - Don't load `Crystal::Scheduler`; - Plug `ExecutionContext` instead of `Crystal::Scheduler` in `spawn`, `Fiber`, ... This is only the skeleton: there are no implementations (yet). Trying to compile anything with `-Dexecution_context` will fail until the ST and/or MT context are implemented. Co-authored-by: Johannes Müller <straightshoota@gmail.com>
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…tal-lang#15350] It's pointless because we always add the default context anyway. Let's make the initialization explicit.
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Introduced in crystal-lang/crystal#15350
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Integrates the skeleton as per RFC #0002.
ExecutionContextmodule;ExecutionContext::Schedulermodule;execution_contextcompile-time flag.When the
execution_contextflag is set:Crystal::Scheduler;ExecutionContextinstead ofCrystal::Schedulerinspawn,Fiber, ...This is only the skeleton: there are no implementations (yet). Trying to compile anything with
-Dexecution_contextwill obviously fail until the follow up pull requests implementing at least the ST and/or MT context are merged.TODO:
Fiber.newafter InitializeFiberwith an explicit stack #15409 is merged;havenot needed: this is already done case inFiber::ExecutionContext#spawnto useself.stack_poolwhen creating the fiber.Fiber.new(with special case when interpreted);Fiber::Queuehas been renamedFiber::Listin Add fiber queues for execution context schedulers #15345Thread#dead_fiber_stack?(Void*vsFiber::Stack)refs #15342
depends on #15345