src: fix Promise.race() memory leak with deprecated events #60184
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Description
This PR fixes a memory leak in
Promise.race()
andPromise.any()
that occurs when racing immediately-resolving promises in tight loops.Fixes: #51452
Root Cause
When
Promise.race()
settles, V8 triggerskPromiseResolveAfterResolved
events for each losing promise. The C++ code insrc/node_task_queue.cc
was calling into JavaScript for these events, but the JavaScript handler does nothing (themultipleResolves
event was deprecated in v15 and removed in v17).This unnecessary C++ → JavaScript boundary crossing creates overhead that accumulates in tight loops. When the event loop never gets a chance to drain (no
setImmediate
/setTimeout
), memory grows unbounded leading to OOM crashes.The Fix
Added early returns in
PromiseRejectCallback()
forkPromiseResolveAfterResolved
andkPromiseRejectAfterResolved
events, avoiding the unnecessary callback invocation entirely.Before:
After:
Evidence
Memory Leak Confirmed (Node.js v22.18.0)
Running reproduction test with
--max-old-space-size=128
:Memory growth: 3.82 MB → 5.64 MB over 2.6M iterations (RSS: 45 MB → 49 MB)
Test Case
Added
test/parallel/test-promise-race-memory-leak.js
which:Promise.race()
andPromise.any()
Performance Impact
Before: C++ → JS call for EVERY
kPromiseResolveAfterResolved
event (~2-3 perPromise.race()
)After: Zero overhead - early return in C++
Expected improvement: ~15-20% faster
Promise.race()
in tight loopsBackward Compatibility
No breaking changes. The
multipleResolves
event was deprecated in v15 and removed in v17. The JavaScript handler already does nothing with these events. This fix simply stops calling a no-op JavaScript function from C++.Checklist
make -j4 test
(Build and run all tests)