mirror of
https://github.com/johnkerl/miller.git
synced 2026-07-18 00:45:47 +00:00
99b8fbdcd5
* Batch-allocate per-record objects; reuse CSV writer field buffer After batch-arena field allocation, profiling cat over 1M-record CSV showed the remaining ~5M allocations were almost entirely per-record (one each): the Mlrmap struct, the RecordAndContext wrapper, the CSV writer's []string, and the go-csv parser's own buffers. Address the first three: - mlrval.RecordArena gains NewRecord(), vending the Mlrmap struct itself from a per-batch slab (respecting --no-hash-records). Rolled out to every line-based reader (CSV, CSV-lite, TSV, DKVP, NIDX, PPRINT, XTAB, DKVPX) in place of NewMlrmapAsRecord. - The CSV reader batch-allocates RecordAndContext wrappers from a per-batch slab instead of one heap object per record (comment/output-string entries still allocate individually, but they are rare). - RecordWriterCSV reuses a single fieldsBuffer []string across records instead of allocating one per Write; WriteCSVRecordMaybeColorized consumes it synchronously and the writer is single-goroutine, so this is safe. Effect (big.*, 1M records, cat, best of 5): csv 0.26 -> 0.22 dkvp 0.51 -> 0.45 (Mlrmap slab) For CSV, cat's allocation-object count drops ~5.0M -> ~2.1M. The remaining ~2M are the go-csv parser's per-record backing string and field slice, which are intrinsic to parsing and would require a zero-copy/batch-slab parser rework. A CPU profile of cat now shows it is I/O-bound (syscall ~56%, bufio read+flush), with allocation/GC down to ~10% -- i.e. further allocation trimming no longer moves cat's wall-clock. GOGC=off confirms (no change). Verified: go test ./pkg/... and full regression suite pass; output is byte-identical across all formats including record-retaining verbs (tac), hashed and --no-hash-records. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * Pool DSL stack frames across records (~8-9% on put) A StackFrameSet lives on the persistent runtime.State and is reused across all records, but every block entry (StatementBlockNode.Execute does PushStackFrame/PopStackFrame, which runs once per record for the main block, plus once per if/for/etc.) allocated a fresh StackFrame -- a []*var slice and a map[string]int -- and discarded it on exit. For `put`/`filter` that is millions of throwaway allocations. Since push/pop is strictly LIFO, retain popped frames in a per-frameset free list and clear-and-reuse them on the next push. After the first record establishes the max block-nesting depth, per-record block execution is allocation-free for frames. len(stackFrames) remains the logical depth, so get/set/defineTyped/unset/etc. are unchanged. Measured (big.csv, 1M rows, best of 4): put chain-1 0.78 -> 0.72 (~8%) put chain-4 0.96 -> 0.87 (~9%) Allocation objects for put chain-1 drop ~23.1M -> ~20.0M (the per-record newStackFrame churn, ~2.86M, is eliminated). UDF calls still allocate a fresh frameset per call (PushStackFrameSet); pooling those is a separate change. The dominant remaining DSL allocator is FromFloat (~6.8M, interior arithmetic temporaries); eliminating it needs node-owned result slots + in-place bif variants, a much larger and aliasing-sensitive change, left for follow-up. Verified: go test ./pkg/... and full regression suite pass; put output is byte-identical, including UDFs with locals/loops/blocks. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com> |
||
|---|---|---|
| .. | ||
| auxents | ||
| bifs | ||
| cli | ||
| climain | ||
| colorizer | ||
| dkvpx | ||
| dsl | ||
| entrypoint | ||
| go-csv | ||
| input | ||
| lib | ||
| mlrval | ||
| output | ||
| parsing | ||
| pbnjay-strptime | ||
| platform | ||
| runtime | ||
| scan | ||
| stream | ||
| terminals | ||
| transformers | ||
| types | ||
| version | ||
| README.md | ||
Please see ../../README-dev.md for an overview; please see each subdirectory for details about it.