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84b4dd56be
* 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>
* Pool DSL stack-frame *sets* across UDF/subr calls (~31% on function-heavy put)
Companion to the per-block frame pooling: that left PushStackFrameSet /
PopStackFrameSet (entered once per user-defined function or subroutine call)
allocating. Each call did newStackFrameSet() -- a StackFrameSet plus its
initial StackFrame (a slice and a map) -- AND, worse, prepended it with
append([]*StackFrameSet{head}, sets...), allocating a fresh backing slice and
copying the whole save-stack every call.
Two changes:
- Treat the frameset save-stack as a tail stack (append to push, truncate to
pop) instead of prepending at index 0. get/set only ever touch the cached
head, so list order is irrelevant; this removes the per-call slice
realloc + O(depth) copy.
- Pool popped framesets (LIFO) and reset-and-reuse them on the next push,
mirroring the per-frameset frame free list. A reset trims back to one
cleared base frame (extras go to the frame pool). After warmup, repeated
calls allocate no framesets or frames.
Measured (big.csv, 1M rows, best of 5):
put, 2 nested func calls/record: 2.73 -> 1.87 (~31%)
GC cycles 25 -> 16; newStackFrameSet/newStackFrame fall out of the allocation
profile entirely. (chain-1 etc. have no UDFs and are unaffected.)
Verified: go test ./pkg/... and full regression suite pass; recursion
(fact/fib), local-scope isolation, and subroutine+oosvar all correct.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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| .. | ||
| doc.go | ||
| README.md | ||
| stack.go | ||
| state.go | ||
Contains state for the CST executor.