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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> |
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| .. | ||
| channel_writer.go | ||
| doc.go | ||
| file_output_handlers.go | ||
| README.md | ||
| record_writer.go | ||
| record_writer_csv.go | ||
| record_writer_csv_colorizer.go | ||
| record_writer_csvlite.go | ||
| record_writer_dcf.go | ||
| record_writer_dkvp.go | ||
| record_writer_dkvpx.go | ||
| record_writer_factory.go | ||
| record_writer_json_jsonl.go | ||
| record_writer_markdown.go | ||
| record_writer_nidx.go | ||
| record_writer_pprint.go | ||
| record_writer_tsv.go | ||
| record_writer_xtab.go | ||
| record_writer_yaml.go | ||
Logic for formatting output records as strings to standard output.
There is one record-writer type per supported output file format, and a factory method.