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src: skip the async id stack when nobody sees it - #66511
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With no async hook and no executionAsyncResource() user, every InternalCallbackScope pushed and popped the async ids on the stack, only for executionAsyncId() and triggerAsyncId() to read the top. Swap the two ids in place instead: they are all that those two and process.nextTick() read. executionAsyncResource() is the only reader of the stack: the scopes that skip it form a chain in AsyncHooks, counted in a new field, kLazyScopes, and JS asks C++ for the innermost one only while that count is not zero. The checks for a corrupted stack stay. Refs: nodejs/performance#24 Signed-off-by: Nigro Simone <nigro.simone@gmail.com>
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #66511 +/- ##
==========================================
- Coverage 92.86% 90.49% -2.37%
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Files 428 797 +369
Lines 195100 278432 +83332
Branches 30147 53496 +23349
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+ Hits 181175 251979 +70804
- Misses 13597 16810 +3213
- Partials 328 9643 +9315
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With no async hook and no
executionAsyncResource()user, every InternalCallbackScope pushes and pops the async ids on the stack, only forexecutionAsyncId()andtriggerAsyncId()to read the top. This swaps the two ids in place instead: they are all that those two andprocess.nextTick()read, so the readers pay nothing.executionAsyncResource()is the only reader of the stack. The scopes that skip it form a chain in AsyncHooks, counted in a new fieldkLazyScopes, and JS asks C++ for the innermost one only while that count is not zero. The checks for a corrupted stack stay: test/async-hookstest-improper-orderandtest-emit-*-on-destroyedfail without them, because the main script runs in a scope that starts before any hook.compare.js on
napi/make_callback, 30 runs, Linux x64, one core, on main (3e5c8af, with #66395):MakeCallback goes from 128.0 to 119.3 ns at n=1e7. test/async-hooks, the async hooks, AsyncLocalStorage, AsyncResource and nextTick tests in test/parallel, and the new addon test pass.
The new field and the chain are the part to look at first, the design was discussed in nodejs/performance#24.
Disclosure: I used Opus 5.5 (Max) as coding assistant