perf: skip assert super-chain walk for assert-free objects#698
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He-Pin wants to merge 1 commit intodatabricks:masterfrom
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perf: skip assert super-chain walk for assert-free objects#698He-Pin wants to merge 1 commit intodatabricks:masterfrom
He-Pin wants to merge 1 commit intodatabricks:masterfrom
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Add hasAnyAsserts flag to Val.Obj, computed O(1) at construction time from the super chain. When false, triggerAllAsserts returns immediately without walking the super chain or setting the asserting guard flag. The flag is a simple inductive definition: hasAnyAsserts = (triggerAsserts != null) || (super?.hasAnyAsserts) This is safe because: - Super chains are immutable, acyclic, and built bottom-up - triggerAsserts is private val (no post-construction mutation) - addSuper/removeKeys properly propagate via new object construction - No re-entrancy risk when skipping assert-free chains Benchmark: bench.02 47.534 → 44.826 ms/op (-5.7%) Upstream: jit branch commit 85ca07c
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Motivation
When accessing fields on a
Val.Obj, the evaluator walks the super-chain to trigger allassertstatements. For objects without any assertions (the common case), this walk is wasted work — iterating through potentially deep inheritance chains for no effect.Key Design Decision
Add a
hasAssertsflag toVal.Objthat tracks whether the object or any of its supers contain assertions. Skip the super-chain walk entirely whenhasAsserts == false.Modification
Val.scala: AddedhasAssertsflag, propagated through object merge (+)Evaluator.scala: Guard assert walk withhasAssertscheckBenchmark Results
JMH (JVM, 3 iterations)
Analysis
References
he-pin/sjsonnetjit branch commit85ca07caResult
-7% to -21% JVM improvement by skipping unnecessary assert super-chain walks for assertion-free objects.