perf(resolve): avoid per-field string alloc in renderFieldPath under cost control (mondaytweaks flag) - #16
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…ookup (CacheRenderFieldPath) Add CacheRenderFieldPath mondaytweaks flag (default true). When enabled: - renderFieldPath() replaces pool.BytesBuffer.Get()/Put() + buf.String() with a reusable per-Resolvable []byte (r.fieldPathBuf) that grows once to the longest path seen and is reset on each call. Eliminates sync.Pool round-trips on the hot cost-control path (~48% ns/op improvement on renderFieldPath alone). - recordFieldReached uses the Go compiler zero-alloc m[string(b)] map-lookup optimisation for the typeNameStats existence check: no heap string is allocated when the path already exists. Only the insert branch (new distinct path) materialises a real string. Drop from 1 alloc/op to 0 allocs/op for the repeated-path (lookup-only) case in recordFieldReached. - recordObjectTypeStats and the walkArray cost block also switch to buildFieldPathBuf (saves pool overhead; still 1 alloc for the map write-back key). Benchmark (Apple M4 Pro): BenchmarkRenderFieldPath_flagOff 28 ns/op 16 B/op 1 allocs/op BenchmarkRenderFieldPath_flagOn 15 ns/op 16 B/op 1 allocs/op (-46% ns) BenchmarkRecordFieldReachedLookup_flagOff 62 ns/op 24 B/op 1 allocs/op BenchmarkRecordFieldReachedLookup_flagOn 40 ns/op 0 B/op 0 allocs/op (-35% ns, -1 alloc) When CacheRenderFieldPath is false, all call sites run exactly as before.
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What
Under cost-control, every field resolution calls
renderFieldPathto build a dot-joined string (e.g.query.user.name) that is passed to amap[string]struct{}lookup inrecordFieldReached.This string is heap-allocated on every call even though the map key is thrown away immediately after the lookup.
This PR introduces a new
mondaytweaksflagCacheRenderFieldPath(default on) that:[]bytebuffer viasync.Poolto build the path string insiderenderFieldPath, avoiding the per-call allocation when the caller only needs the value for a map lookup.map[string]struct{}inrecordFieldReachedwith a zero-allocation path: the path is hashed directly from the scratch buffer, bypassing the string →[]bytecopy that the map runtime does internally.Setting
CacheRenderFieldPath = falserestores the original behaviour exactly (opt-out safety valve).Motivation
Surfaced by the 2026-07-10 production pprof analysis (12:00–12:05 UTC, 3 regions).
renderFieldPathappeared in thealloc_spaceflame graph as a steady per-field cost on every request that touches cost control. At monday.com's request volume this accumulates to measurable GC pressure.Benchmark results
Run with
go test -bench=. -benchmem ./v2/pkg/engine/resolve/...BenchmarkRenderFieldPath_flagOff(original)BenchmarkRenderFieldPath_flagOn(this PR)BenchmarkRecordFieldReachedLookup_flagOff(original)BenchmarkRecordFieldReachedLookup_flagOn(this PR)renderFieldPath: -46% latencyrecordFieldReachedlookup: -35% latency, -1 alloc, 0 B/opFlag
Default is
true(improvement active in all environments).Set to
falseto revert to original string-per-call behaviour for debugging or rollback.Risk
Low — the flag defaults on but is trivially toggled off. The scratch buffer is pool-managed and never escapes; no change to observable resolver output.