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src: keep ALS store in AsyncResource::MakeCallback - #66326
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AsyncResource saves the async context frame when it is created, and MakeCallback() enters it with async_context_frame::Scope. Then node::MakeCallback() opens the callback scope with an undefined frame, so the callback never runs in the saved one. Since AsyncContextFrame is the default, AsyncLocalStorage loses its store in these callbacks. Pass the saved frame to InternalMakeCallback(), as the Node-API AsyncContext already does. This also removes the Scope from every call, with its two Environment lookups and its global handle. Refs: nodejs#66316 Refs: nodejs#43038 Refs: nodejs/performance#24 Signed-off-by: Nigro Simone <[email protected]>
type=AsyncResource calls node::AsyncResource::MakeCallback() and type=Call a plain v8::Function::Call, from the same libuv timer as type=MakeCallback. Call is what the call costs without Node. Signed-off-by: Nigro Simone <[email protected]>
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #66326 +/- ##
==========================================
+ Coverage 90.36% 90.45% +0.09%
==========================================
Files 792 791 -1
Lines 275498 276571 +1073
Branches 52798 53114 +316
==========================================
+ Hits 248947 250172 +1225
+ Misses 16976 16799 -177
- Partials 9575 9600 +25
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This was referenced Sep 29, 2026
anonrig
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A test case like this fails with the PR:
'use strict';
const common = require('../../common');
const assert = require('assert');
const { AsyncLocalStorage } = require('async_hooks');
const binding = require(`./build/${common.buildType}/binding`);
const als = new AsyncLocalStorage();
let getterStore;
const object = Object.defineProperty({}, 'methöd', {
get() {
getterStore = als.getStore();
als.enterWith('getter'); // <= this leaks out the MakeCallback
return () => {};
},
});
const resource =
als.run('resource', () => binding.createAsyncResource(object));
let actual;
als.run('caller', () => {
binding.callViaString(resource);
actual = [getterStore, als.getStore()];
});
binding.destroyAsyncResource(resource);
assert.deepStrictEqual(actual, ['resource', 'caller']);
// With this PR, this results in ['resource', 'getter'] instead.| if (!env_->can_call_into_js()) return {}; | ||
| Local<Value> callback; | ||
| if (!get_resource() | ||
| ->Get(isolate->GetCurrentContext(), symbol) |
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This could call into JS and should be scoped with a async_context_frame::Scope.
Signed-off-by: Nigro Simone <[email protected]>
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Thanks, you are right. Fixed in 78d5c35: the Get() runs in the saved frame again, and your case is in test-async-local-storage.js, it fails without the fix. |
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Would you mind confirming if the performance gain still preserve after the change? IIUC it changes the claim in the OP. |
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Yes, it holds. The benchmark calls So by function it is still ~27% faster, and by name it costs the same as before. I updated the description: the two Environment lookups and the global handle are saved only on the function overload. |
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CI is green, could someone add commit-queue? Same for #66344. |
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@legendecas thanks for the review. CI is green (78290), could you add commit-queue? |
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AsyncResource saves the async context frame when it is created, and MakeCallback() enters it with async_context_frame::Scope. Then node::MakeCallback() opens the callback scope with an undefined frame, so the callback never runs in the saved one. Since AsyncContextFrame is the default (v24), AsyncLocalStorage loses its store in the callbacks of node::AsyncResource. With --no-async-context-frame the store is there.
Now MakeCallback() passes the saved frame to InternalMakeCallback(), as the Node-API AsyncContext already does. On the function overload the Scope goes away, so every call also saves two Environment lookups and a global handle. The overloads by method name keep it around the Get(), as a getter can call into JS.
The new test fails without the change: the store is undefined in the callback.
The second commit adds type=AsyncResource and type=Call to the make_callback benchmark added in #66316. Call is a plain v8::Function::Call, what the call costs without Node. benchmark/compare.js, 30 runs, Linux x64:
Refs: #43038
Refs: nodejs/performance#24
Disclosure: I used Opus 5.5 (Max) as coding assistant