Parallel sheet reads from one reader, positional sources and reader lifetime (v5.2.0) by GabrielMarquezMatte · Pull Request #135 · GabrielMarquezMatte/ExcelReader

GabrielMarquezMatte · 2026-10-06T17:47:28Z

What does this change?

Enumerators obtained from one reader can now be consumed on different threads, for XLSX, XLSB, XLS
and CSV, and a reader's file or stream stays open until its last enumerator is disposed. To get
there, every source is read positionally and XLSX/XLSB stop using ZipArchive on the read path.
The public API is unchanged.

Positional sources. New internal ByteSource (memory, file handle, seekable stream) and
ByteSourceStream. ZipIndex (formerly ZipMemoryIndex) reads its directory and entries through
any ByteSource, so XLSX and XLSB from a path or a stream no longer go through
System.IO.Compression.ZipArchive. XLS loads its sectors the same way. A non-seekable stream is
buffered to memory at open for XLSX, XLSB and XLS.
Shared state is safe to share. The decompressed-byte counter is atomic, cached shared strings
are published with compare-and-swap, and the XLSX shared-string table is loaded once behind a gate
that records a failure and undoes a cancelled load.
Reader lifetime. A reference count ties the pooled buffers, the ZIP index and the source to the
reader and its live enumerators.
CSV. Memory, file paths and seekable streams are read positionally, so several enumerators can
run at once. A non-seekable stream is still one streaming pass and is not buffered.
Before the above (8379db3). WriteRecordBatch accepts more Arrow types; XLSB and XLS yield
rows written without cells, as XLSX does; the CSV structural scanner uses PMULL on ARM.

Behaviour changes

Using a reader after Dispose throws ObjectDisposedException.
Disposing a reader no longer closes its file or stream while an enumerator from it is undisposed.
An enumerator that is never disposed keeps the file open.
A failed XLSX shared-string load fails every later enumeration the same way. It used to yield empty
strings on the second attempt.
A CSV read over a seekable stream no longer leaves the caller's stream at the end.
XLSB and XLS readers yield rows that have no cells; the XLS writer emits a blank cell for such a row.
ZipIndex accepts trailing bytes after the end-of-central-directory record and rejects stored
entries whose two sizes disagree.

Not in this PR

The v6 API (IExcelWorkbook, sheet values, removal of IExcelRowReader). "Current sheet" and
MoveToSheet are still unsynchronized: select sheets and create enumerators from one thread.

Checklist

dotnet build ExcelReader.slnx --configuration Release builds clean (warnings are errors)
dotnet test tests/ExcelReader.Tests/ExcelReader.Tests.csproj --configuration Release passes
If this changes the public API: PublicAPI.Unshipped.txt updated (no public API change; the file is empty)
Tests added/updated for the behavior change
One focused change — unrelated fixes are in a separate PR (this is the 5.2.0 release branch: 28 commits)

Test plan

Full suite: 2767 passing (2672 before this work), run twice with no flaky test.
New tests: ByteSource and ByteSourceStream per source kind; ZipIndex over positional sources
including ZIP64 and failure paths; lifetime per format (enumerator outlives its reader, double
dispose, failed open releases the reader); concurrent sheets across XLSX/XLSB/XLS and
memory/stream/path, sync and async (27 cases, five consecutive runs); CSV with concurrent
enumerators per source kind.
Fuzz smoke: check <seeds> 512 with seeds 1 and 7, 349,866 cases, 0 failures.
Sequential reads, pinned to one core, alternated builds: no line slower than before by more than
1.5% on both lowest and median (XLSX and XLSB by path, FileStream and memory; CSV by path,
FileStream and memory).
One reader with six sheets read in parallel against one reader per sheet (best of 5):
XLSX 59 ms vs 65 ms, XLSB 67 ms vs 88 ms; sequential 225 ms and 206 ms.
Not run locally: the Python, Rust and C++ binding suites (their files and the C ABI are unchanged;
CI covers them), and a long fuzz run on ZipIndex.

… empty rows in readers

…seekable streams Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…Source Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…o the central directory Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…yteSource Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…e from the read path Excel.cs detects and dispatches with a ZipIndex; the Reopen* helpers, ZipEntryBytes, ZipReaderOpen and the ZipArchive helpers in WorkbookLookups are gone. Tests: deleted ZipIndexTests.ZipEntryBytesReadThrowsInvalidDataWhenEntryUnderDelivers (sole subject was ZipEntryBytes); rewrote the ReadViaZipArchive helper in ZipIndexTests to read the entry through ZipArchive directly. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…g a shared stream Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…P index ZIP64 fixtures now also run through a stream source, sync and async. The mutation differential test covers sync and async part and entry-stream reads. Entry streams are compared with the memory entry stream, since streams never verify declared sizes on any source. Reader entry points are checked for disposing the stream on failure, and the "less data than declared" guard is covered again. No product defect found. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…exact stream types Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

DecompressedByteCounter.Add and Remaining are now thread-safe via Interlocked.Add and Interlocked.Read, enabling concurrent sheet inflation under a shared decompression limit. Once any thread exceeds the limit, all subsequent Add calls throw—captured atomically in _total regardless of order. Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Replace lazy-initialization with thread-safe compare-and-swap in Cell.GetString() and each reader's SharedStringCache property. Materializes cache array once per reader; filled slots never change, ensuring enumerators on different threads see consistent string references and cached values. Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

OnceGate runs a load once for multiple callers. A failure is recorded and rethrown without reloading; cancellation runs reset and lets the next caller load fresh. Sync and async paths share one load. ReaderLifetime is a reference-counted lifetime tracker. The reader holds one reference, each enumerator another. Release runs when the last reference goes. Close is idempotent and prevents new acquisitions once called. Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

…or its enumerators Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…e offsets everywhere ByteSourceStream and ZipIndex throw ObjectDisposedException after Dispose; every ByteSource rejects a negative offset with ArgumentOutOfRangeException. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…uctor throws The constructor reads the header row before it returns. A throw there (a limit, a corrupt sheet) dropped the enumerator it had just taken, and that enumerator's lease kept the reader's source open after the caller disposed the reader. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…sources Enumerators created on one thread from a single XLSX, XLSB or XLS reader (memory, stream and path sources) are drained on separate threads, sync and async, and must match a sequential read. Threads reading one sheet must get the very same shared-string instances (equal strings for XLS labels). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dispose left the deferred-open flag set, so a MoveNext after Dispose opened a new sheet stream and buffers with no lease. Clear the flag in Dispose and DisposeAsync, and mark the cursor at end of data once its buffers are returned so a use after dispose reports no rows instead of waiting for a source that never comes. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

…numerators CsvReader over a seekable stream wraps it in a ByteSource and gives every enumerator its own positional view, so enumerators no longer share or rewind one Stream and can run concurrently. The reader holds a ReaderLifetime: Dispose closes it to new enumerators and its file or stream is released when the last enumerator is disposed. A non-seekable stream serves a single enumerator. Rewrites the thread-safety remark of IExcelRowReader accordingly. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

A FileStream opened with a non-UTF-8 encoding would hand parallel chunking the raw, untranscoded file. The only caller already filters on encoding, so this was latent. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The positional stream buffered 64K of its own under a consumer that already buffers, copying every byte twice. It now takes an unbuffered mode, used for CSV when no transcoding stream sits in between. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

codecov-commenter · 2026-10-06T17:53:35Z

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 91.30435% with 72 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.88%. Comparing base (fe522c5) to head (1723f07).

Files with missing lines	Patch %	Lines
...xcelReader.Core/Reader/Sources/ByteSourceStream.cs	77.61%	12 Missing and 3 partials ⚠️
src/ExcelReader.Core/Reader/Xlsb/XlsbReader.cs	87.67%	7 Missing and 2 partials ⚠️
src/ExcelReader.Core/Reader/Xlsx/XlsxReader.cs	84.21%	7 Missing and 2 partials ⚠️
src/ExcelReader.Core/Reader/Internal/OnceGate.cs	85.36%	3 Missing and 3 partials ⚠️
src/ExcelReader.Core/Reader/Sources/ByteSource.cs	88.67%	4 Missing and 2 partials ⚠️
src/ExcelReader.Core/Reader/Xls/XlsReader.cs	71.42%	6 Missing ⚠️
src/ExcelReader.Core/Reader/Zip/ZipIndex.cs	97.54%	2 Missing and 3 partials ⚠️
src/ExcelReader.Arrow/ArrowWriteExtensions.cs	90.69%	4 Missing ⚠️
src/ExcelReader.Core/Reader/Csv/CsvReader.cs	93.02%	1 Missing and 2 partials ⚠️
...xcelReader.Core/Reader/Csv/CsvStructuralScanner.cs	0.00%	3 Missing ⚠️
... and 4 more
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
+ Coverage   89.45%   89.88%   +0.42%     
==========================================
  Files         181      185       +4     
  Lines       13612    13911     +299     
  Branches     2515     2550      +35     
==========================================
+ Hits        12177    12504     +327     
+ Misses        956      941      -15     
+ Partials      479      466      -13

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github-actions · 2026-10-06T17:58:47Z

Benchmark Results

Baseline: master fe522c52, from the series published by benchmark-pages.yml. Both sides ran on a shared ubuntu-latest runner, so treat anything under ±10% as noise.

Moved by at least 10%

Benchmark	master	This PR	Delta
`ExcelReader.Benchmarks.RecordWriteBenchmark.Xls(Rows: 50000)`	6.49 ms	8.23 ms	+26.9%
`ExcelReader.Benchmarks.ReadBenchmark.OfficeIMO(Rows: 50000)`	160.78 ms	203.65 ms	+26.7%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsx_Sylvan(Rows: 65536)`	156.43 ms	189.03 ms	+20.8%
`ExcelReader.Benchmarks.RecordWriteBenchmark.CsvMapped(Rows: 50000)`	7.33 ms	8.76 ms	+19.5%
`ExcelReader.Benchmarks.DataReaderBenchmark.DataTable_Load(Rows: 50000)`	52.88 ms	62.43 ms	+18.1%
`ExcelReader.Benchmarks.XlsWriteBenchmark.XlsWriter(Rows: 50000)`	7.11 ms	8.37 ms	+17.7%
`ExcelReader.Benchmarks.WritePathBenchmark.StyledRows_Xlsx`	8.77 ms	10.29 ms	+17.4%
`ExcelReader.Benchmarks.XlsWriteBenchmark.XlsxWriter(Rows: 50000)`	14.40 ms	16.59 ms	+15.2%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsx_ExcelReader_Materialized_Interned(Rows: 65536)`	55.55 ms	63.77 ms	+14.8%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsb_ExcelReader_Materialized_Interned(Rows: 65536)`	48.42 ms	55.58 ms	+14.8%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsx_ExcelReader_Materialized(Rows: 65536)`	54.22 ms	61.91 ms	+14.2%
`ExcelReader.Benchmarks.RealDataReadBenchmark.Xlsx_ExcelReader_Memory_Prefetch`	45.63 ms	51.99 ms	+13.9%
`ExcelReader.Benchmarks.CsvWriteBenchmark.Sep(Rows: 50000)`	9.33 ms	10.55 ms	+13.0%
`ExcelReader.Benchmarks.WriteBenchmark.ExcelReaderWriter(Rows: 50000)`	14.67 ms	16.51 ms	+12.5%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsb_ExcelReader_Materialized(Rows: 65536)`	48.91 ms	55.04 ms	+12.5%
`ExcelReader.Benchmarks.RecordWriteBenchmark.Xlsb(Rows: 50000)`	10.06 ms	11.30 ms	+12.3%
`ExcelReader.Benchmarks.WriteBenchmark.ExcelReaderWriterSharedStrings(Rows: 50000)`	14.32 ms	16.05 ms	+12.1%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsb_ExcelReader(Rows: 65536)`	32.21 ms	35.91 ms	+11.5%
`ExcelReader.Benchmarks.WriteBenchmark.ExcelReaderWriterPrefetch(Rows: 50000)`	11.07 ms	12.32 ms	+11.2%
`ExcelReader.Benchmarks.WritePathBenchmark.NativeStrings_Csv`	6.66 ms	7.40 ms	+11.2%
`ExcelReader.Benchmarks.RealDataReadBenchmark.Xlsx_ExcelReader_Prefetch`	47.00 ms	52.21 ms	+11.1%
`ExcelReader.Benchmarks.RealDataReadBenchmark.Xlsm_ExcelReader_Prefetch`	45.52 ms	50.46 ms	+10.9%
`ExcelReader.Benchmarks.StringHeavyReadBenchmark.Xlsb_Sylvan(Rows: 65536)`	53.73 ms	59.23 ms	+10.2%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.Sep_Parallel(Corpus: NarrowInt)`	458.72 ms	408.54 ms	-10.9%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserStructSync(Rows: 50000)`	15.46 ms	13.61 ms	-11.9%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowInt(Dop: 1)`	801.66 ms	704.92 ms	-12.1%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowInt(Dop: 4)`	472.47 ms	414.42 ms	-12.3%
`ExcelReader.Benchmarks.ParseBenchmark.SylvanAsync(Rows: 50000)`	89.70 ms	78.45 ms	-12.5%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.ExcelReader_Sequential(Corpus: ConversionHeavy)`	957.15 ms	836.79 ms	-12.6%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserSync(Rows: 50000)`	16.56 ms	14.34 ms	-13.4%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavyAggregate(Dop: 2)`	740.68 ms	639.20 ms	-13.7%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Encrypted_OpenOnly`	44.88 ms	38.68 ms	-13.8%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserXlsbSync(Rows: 50000)`	11.90 ms	10.10 ms	-15.1%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavy(Dop: 4)`	774.11 ms	651.26 ms	-15.9%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.Sep_Parallel(Corpus: ConversionHeavy)`	813.60 ms	682.27 ms	-16.1%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavy(Dop: 8)`	760.80 ms	636.32 ms	-16.4%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavyAggregate(Dop: 16)`	503.59 ms	420.40 ms	-16.5%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavy(Dop: 16)`	763.79 ms	637.10 ms	-16.6%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserXlsbAsync(Rows: 50000)`	12.24 ms	10.21 ms	-16.6%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowIntAggregate(Dop: 2)`	490.19 ms	408.79 ms	-16.6%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowInt(Dop: 16)`	472.63 ms	392.44 ms	-17.0%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavyAggregate(Dop: 8)`	500.38 ms	414.20 ms	-17.2%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavy(Dop: 1)`	1.46 s	1.20 s	-17.5%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowIntAggregate(Dop: 4)`	311.19 ms	254.04 ms	-18.4%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.Sep_Sequential(Corpus: ConversionHeavy)`	1.18 s	957.88 ms	-18.8%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserSyncSharedStrings(Rows: 50000)`	16.30 ms	13.21 ms	-19.0%
`ExcelReader.Benchmarks.CsvParseBenchmark.ExcelParserAsync(Rows: 50000)`	7.35 ms	5.95 ms	-19.0%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.ExcelReader_Parallel(Corpus: ConversionHeavy)`	563.08 ms	455.56 ms	-19.1%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowIntAggregate(Dop: 16)`	321.72 ms	259.19 ms	-19.4%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowIntAggregate(Dop: 8)`	316.57 ms	252.86 ms	-20.1%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowInt(Dop: 8)`	489.10 ms	390.53 ms	-20.2%
`ExcelReader.Benchmarks.ParseBenchmark.ExcelParserAsync(Rows: 50000)`	18.53 ms	14.73 ms	-20.5%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowInt(Dop: 2)`	703.50 ms	556.85 ms	-20.8%
`ExcelReader.Benchmarks.CsvParallelVsSepBenchmark.ExcelReader_Parallel(Corpus: NarrowInt)`	493.02 ms	390.09 ms	-20.9%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Encrypted_Stream_VerifyIntegrity`	44.40 ms	34.77 ms	-21.7%
`ExcelReader.Benchmarks.ParseBenchmark.RefStructModelSync(Rows: 50000)`	15.55 ms	12.14 ms	-21.9%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Large_Encrypted_OpenOnly`	44.68 ms	34.78 ms	-22.2%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.NarrowIntAggregate(Dop: 1)`	733.63 ms	568.35 ms	-22.5%
`ExcelReader.Benchmarks.CsvParseBenchmark.ExcelParserSync(Rows: 50000)`	7.23 ms	5.60 ms	-22.6%
`ExcelReader.Benchmarks.CsvParseBenchmark.Sylvan(Rows: 50000)`	19.28 ms	14.65 ms	-24.0%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavy(Dop: 2)`	1.14 s	865.28 ms	-24.2%
`ExcelReader.Benchmarks.CsvParallelParseBenchmark.ConversionHeavyAggregate(Dop: 1)`	1.19 s	902.70 ms	-24.3%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Encrypted_Memory`	44.41 ms	33.55 ms	-24.4%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Large_Encrypted_Stream`	94.01 ms	69.84 ms	-25.7%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Encrypted_Stream`	50.15 ms	36.88 ms	-26.5%
`ExcelReader.Benchmarks.CsvParseBenchmark.Sep(Rows: 50000)`	14.65 ms	10.58 ms	-27.8%
`ExcelReader.Benchmarks.ColdStartBenchmark.FluentParseFirstUse(Rows: 200)`	38.45 ms	26.83 ms	-30.2%
`ExcelReader.Benchmarks.ColdStartBenchmark.TypedParseFirstUse(Rows: 200)`	42.83 ms	29.88 ms	-30.2%
`ExcelReader.Benchmarks.CsvReadBenchmark.ExcelReader(Rows: 50000)`	5.92 ms	4.07 ms	-31.2%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Large_Plain_Stream`	50.46 ms	34.03 ms	-32.6%
`ExcelReader.Benchmarks.ColdStartBenchmark.FluentParseWithAttributeFallbackFirstUse(Rows: 200)`	47.95 ms	31.70 ms	-33.9%
`ExcelReader.Benchmarks.NativeRowReadBenchmark.ReadAllBlob`	58.99 ms	37.91 ms	-35.7%
`ExcelReader.Benchmarks.NativeRowReadBenchmark.NextRowBlob`	54.49 ms	33.78 ms	-38.0%
`ExcelReader.Benchmarks.NativeRowReadBenchmark.NextRowDecoded`	61.82 ms	38.18 ms	-38.2%
`ExcelReader.Benchmarks.ColdStartBenchmark.RecordWriteFirstUse(Rows: 200)`	26.28 ms	15.89 ms	-39.5%
`ExcelReader.Benchmarks.NativeTypedParseBenchmark.ParseTyped`	52.60 ms	31.64 ms	-39.8%
`ExcelReader.Benchmarks.EncryptedWorkbookBenchmark.Plain_Stream`	59.22 µs	33.51 µs	-43.4%
`ExcelReader.Benchmarks.NativeTypedParseBenchmark.ParseArrow`	51.45 ms	28.58 ms	-44.4%
`ExcelReader.Benchmarks.ChunkedParseBenchmark.Batched_1k(Rows: 50000)`	12.90 ms	7.07 ms	-45.2%
`ExcelReader.Benchmarks.ChunkedParseBenchmark.Batched_10k(Rows: 50000)`	12.91 ms	6.94 ms	-46.2%
`ExcelReader.Benchmarks.ChunkedParseBenchmark.WholeSheet(Rows: 50000)`	13.72 ms	7.10 ms	-48.2%
`ExcelReader.Benchmarks.NativeRowReadBenchmark.ReadAllDecoded`	82.91 ms	42.50 ms	-48.7%

77 within ±10%.

Full results per group

ExcelReader.Benchmarks.ArrowConversionBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V74 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
CsvAllString	100000	22.12 ms	0.541 ms	0.141 ms	1.00	0.01	687.5000	562.5000	562.5000	16.27 MB	1.00
CsvTyped	100000	12.63 ms	0.469 ms	0.122 ms	0.57	0.01	468.7500	421.8750	421.8750	8.13 MB	0.50
XlsbTyped	100000	17.01 ms	2.200 ms	0.571 ms	0.77	0.02	468.7500	437.5000	437.5000	8.14 MB	0.50
CsvTypedWithInference	100000	11.29 ms	0.458 ms	0.119 ms	0.51	0.01	593.7500	562.5000	531.2500	14.89 MB	0.92

ExcelReader.Benchmarks.ChunkedParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 4.40GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	Gen0	Gen1	Allocated	Alloc Ratio
WholeSheet	50000	7.105 ms	0.3098 ms	0.0479 ms	1.00	78.1250	62.5000	1.3 MB	1.00
Batched_10k	50000	6.944 ms	0.3417 ms	0.0887 ms	0.98	93.7500	54.6875	1.59 MB	1.23
Batched_1k	50000	7.066 ms	0.2696 ms	0.0417 ms	0.99	93.7500	7.8125	1.51 MB	1.16

ExcelReader.Benchmarks.ColdStartBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 4.27GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-GOEFXF : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

InvocationCount=1  IterationCount=1  LaunchCount=16  
RunStrategy=ColdStart  UnrollFactor=1  WarmupCount=0

Method	Rows	Mean	Error	StdDev	Allocated
TypedParseFirstUse	200	29.88 ms	1.461 ms	1.435 ms	20.98 KB
RecordWriteFirstUse	200	15.89 ms	0.779 ms	0.765 ms	84.25 KB
FluentParseFirstUse	200	26.83 ms	4.229 ms	4.154 ms	23.5 KB
FluentParseWithAttributeFallbackFirstUse	200	31.70 ms	0.758 ms	0.745 ms	25.2 KB

ExcelReader.Benchmarks.CsvParallelParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
INTEL XEON PLATINUM 8573C 2.30GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Dop	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
ConversionHeavy	1	1,204.5 ms	44.57 ms	6.90 ms	1.00	0.01	8000.0000	-	671.37 MB	1.000
NarrowInt	1	704.9 ms	56.56 ms	14.69 ms	0.59	0.01	3000.0000	-	245.76 MB	0.366
ConversionHeavyAggregate	1	902.7 ms	23.79 ms	6.18 ms	0.75	0.01	-	-	1.17 MB	0.002
NarrowIntAggregate	1	568.3 ms	37.58 ms	9.76 ms	0.47	0.01	-	-	1.15 MB	0.002

ConversionHeavy	2	865.3 ms	60.98 ms	15.84 ms	1.00	0.02	8000.0000	4000.0000	678.7 MB	1.000
NarrowInt	2	556.9 ms	66.04 ms	17.15 ms	0.64	0.02	3000.0000	1000.0000	253.12 MB	0.373
ConversionHeavyAggregate	2	639.2 ms	33.81 ms	8.78 ms	0.74	0.02	-	-	1.22 MB	0.002
NarrowIntAggregate	2	408.8 ms	46.37 ms	12.04 ms	0.47	0.01	-	-	1.23 MB	0.002

ConversionHeavy	4	651.3 ms	33.42 ms	8.68 ms	1.00	0.02	8000.0000	6000.0000	678.78 MB	1.000
NarrowInt	4	414.4 ms	56.02 ms	14.55 ms	0.64	0.02	3000.0000	1000.0000	253.33 MB	0.373
ConversionHeavyAggregate	4	447.0 ms	52.82 ms	13.72 ms	0.69	0.02	-	-	1.22 MB	0.002
NarrowIntAggregate	4	254.0 ms	12.32 ms	3.20 ms	0.39	0.01	-	-	1.23 MB	0.002

ConversionHeavy	8	636.3 ms	52.45 ms	13.62 ms	1.00	0.03	8000.0000	7000.0000	678.81 MB	1.000
NarrowInt	8	390.5 ms	40.21 ms	6.22 ms	0.61	0.01	3000.0000	1000.0000	253.32 MB	0.373
ConversionHeavyAggregate	8	414.2 ms	48.52 ms	12.60 ms	0.65	0.02	-	-	1.23 MB	0.002
NarrowIntAggregate	8	252.9 ms	5.67 ms	0.88 ms	0.40	0.01	-	-	1.26 MB	0.002

ConversionHeavy	16	637.1 ms	50.01 ms	7.74 ms	1.00	0.02	8000.0000	2000.0000	679.27 MB	1.000
NarrowInt	16	392.4 ms	45.41 ms	7.03 ms	0.62	0.01	3000.0000	1000.0000	254.02 MB	0.374
ConversionHeavyAggregate	16	420.4 ms	9.14 ms	1.41 ms	0.66	0.01	-	-	1.29 MB	0.002
NarrowIntAggregate	16	259.2 ms	9.42 ms	2.45 ms	0.41	0.01	-	-	1.31 MB	0.002

ExcelReader.Benchmarks.CsvParallelVsSepBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
INTEL XEON PLATINUM 8573C 2.30GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Corpus	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
ExcelReader_Sequential	NarrowInt	642.7 ms	20.98 ms	5.45 ms	1.00	0.01	3000.0000	-	244.14 MB	1.00
ExcelReader_Parallel	NarrowInt	390.1 ms	26.27 ms	4.06 ms	0.61	0.01	3000.0000	1000.0000	253.15 MB	1.04
Sep_Sequential	NarrowInt	552.0 ms	5.22 ms	1.36 ms	0.86	0.01	3000.0000	-	244.15 MB	1.00
Sep_Parallel	NarrowInt	408.5 ms	59.06 ms	15.34 ms	0.64	0.02	3000.0000	2000.0000	257.6 MB	1.06

ExcelReader_Sequential	ConversionHeavy	836.8 ms	15.89 ms	4.13 ms	1.00	0.01	5000.0000	-	467.3 MB	1.00
ExcelReader_Parallel	ConversionHeavy	455.6 ms	49.65 ms	12.90 ms	0.54	0.01	5000.0000	4000.0000	473.63 MB	1.01
Sep_Sequential	ConversionHeavy	957.9 ms	13.27 ms	2.05 ms	1.14	0.01	5000.0000	-	467.31 MB	1.00
Sep_Parallel	ConversionHeavy	682.3 ms	64.62 ms	16.78 ms	0.82	0.02	6000.0000	5000.0000	477.26 MB	1.02

ExcelReader.Benchmarks.CsvParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
INTEL XEON PLATINUM 8573C 2.30GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	Gen0	Gen1	Allocated	Alloc Ratio
ExcelParserSync	50000	5.597 ms	0.0536 ms	0.0139 ms	1.00	46.8750	-	3.86 MB	1.00
ExcelParserAsync	50000	5.952 ms	0.0708 ms	0.0109 ms	1.06	46.8750	-	3.86 MB	1.00
Sep	50000	10.582 ms	0.2055 ms	0.0318 ms	1.89	46.8750	-	3.87 MB	1.00
Sylvan	50000	14.649 ms	0.1403 ms	0.0364 ms	2.62	125.0000	15.6250	10.95 MB	2.84

ExcelReader.Benchmarks.CsvReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 3.19GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Allocated	Alloc Ratio
ExcelReader	50000	4.071 ms	0.2974 ms	0.0772 ms	1.00	0.02	784 B	1.00
ExcelReaderWide	50000	12.523 ms	0.2030 ms	0.0314 ms	3.08	0.05	784 B	1.00
ExcelReaderAsync	50000	3.964 ms	0.0200 ms	0.0052 ms	0.97	0.02	856 B	1.09
Sep	50000	13.663 ms	0.1800 ms	0.0468 ms	3.36	0.06	4024 B	5.13
Sylvan	50000	5.893 ms	0.0510 ms	0.0079 ms	1.45	0.03	38682 B	49.34

ExcelReader.Benchmarks.CsvWriteBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
ExcelReaderWriter	50000	6.462 ms	0.2263 ms	0.0588 ms	1.00	0.01	500.0000	500.0000	500.0000	4 MB	1.00
Sep	50000	10.551 ms	0.7169 ms	0.1862 ms	1.63	0.03	500.0000	500.0000	500.0000	4.01 MB	1.00
SylvanWriter	50000	10.815 ms	0.2655 ms	0.0689 ms	1.67	0.02	500.0000	500.0000	500.0000	4.04 MB	1.01

ExcelReader.Benchmarks.DataReaderBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V74 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
Baseline_RawRows	50000	8.006 ms	0.0099 ms	0.0026 ms	1.00	0.00	-	-	-	3.73 KB	1.00
DataReader_GetValue	50000	11.050 ms	0.0855 ms	0.0222 ms	1.38	0.00	312.5000	-	-	5131.38 KB	1,374.09
DataReader_TypedGetters	50000	10.977 ms	0.0224 ms	0.0035 ms	1.37	0.00	93.7500	-	-	1615.75 KB	432.67
DataReader_GetBytes	50000	8.423 ms	0.0366 ms	0.0057 ms	1.05	0.00	-	-	-	4.42 KB	1.18
DataTable_Load	50000	62.434 ms	2.3489 ms	0.6100 ms	7.80	0.07	2000.0000	1875.0000	875.0000	23393.35 KB	6,264.33

ExcelReader.Benchmarks.EncryptedWorkbookBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
Plain_Stream	33.51 μs	1.352 μs	0.209 μs	1.00	0.01	0.5493	9.01 KB	1.00
Encrypted_Stream	36,876.78 μs	5,348.495 μs	1,388.987 μs	1,100.48	38.52	-	38.05 KB	4.22
Encrypted_Stream_VerifyIntegrity	34,768.61 μs	1,407.507 μs	365.525 μs	1,037.57	11.55	-	39.98 KB	4.44
Encrypted_Memory	33,554.87 μs	976.205 μs	151.069 μs	1,001.35	6.89	-	53 KB	5.88
Encrypted_OpenOnly	38,681.96 μs	4,660.453 μs	721.210 μs	1,154.35	20.30	-	32.43 KB	3.60
Large_Plain_Stream	34,029.41 μs	499.472 μs	77.294 μs	1,015.51	6.03	-	3.73 KB	0.41
Large_Encrypted_Stream	69,839.37 μs	3,167.099 μs	490.112 μs	2,084.16	17.51	-	29.46 KB	3.27
Large_Encrypted_OpenOnly	34,782.39 μs	2,043.549 μs	530.703 μs	1,037.98	15.63	-	28.86 KB	3.20

ExcelReader.Benchmarks.NativeRowReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 4.40GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
NextRowBlob	33.78 ms	2.293 ms	0.596 ms	1.00	0.02	266.6667	266.6667	266.6667	3.71 MB	1.00
NextRowDecoded	38.18 ms	1.039 ms	0.161 ms	1.13	0.02	285.7143	285.7143	285.7143	3.71 MB	1.00
ReadAllBlob	37.91 ms	2.487 ms	0.646 ms	1.12	0.03	1142.8571	1071.4286	71.4286	21.06 MB	5.68
ReadAllDecoded	42.50 ms	1.199 ms	0.312 ms	1.26	0.02	583.3333	583.3333	583.3333	5.71 MB	1.54

ExcelReader.Benchmarks.NativeTypedParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 4.40GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
ParseTyped	31.64 ms	2.536 ms	0.659 ms	1.00	0.03	812.5000	687.5000	375.0000	11.61 MB	1.00
ParseArrow	28.58 ms	1.906 ms	0.495 ms	0.90	0.02	906.2500	843.7500	437.5000	11.62 MB	1.00

ExcelReader.Benchmarks.ParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
INTEL XEON PLATINUM 8573C 2.30GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
ExcelParserSync	50000	14.34 ms	0.098 ms	0.015 ms	1.00	0.00	46.8750	3959.35 KB	1.000
ExcelParserSyncSharedStrings	50000	13.21 ms	0.582 ms	0.090 ms	0.92	0.01	15.6250	2349.29 KB	0.593
ExcelParserStructSync	50000	13.61 ms	0.054 ms	0.008 ms	0.95	0.00	15.6250	1615.6 KB	0.408
RefStructModelSync	50000	12.14 ms	0.142 ms	0.022 ms	0.85	0.00	-	4.27 KB	0.001
ExcelParserAsync	50000	14.73 ms	0.162 ms	0.042 ms	1.03	0.00	46.8750	3959.44 KB	1.000
ExcelParserXlsbSync	50000	10.10 ms	0.091 ms	0.024 ms	0.70	0.00	46.8750	3959.66 KB	1.000
ExcelParserXlsbAsync	50000	10.21 ms	0.212 ms	0.055 ms	0.71	0.00	46.8750	3959.75 KB	1.000
OfficeIMO	50000	174.72 ms	103.092 ms	26.773 ms	12.18	1.71	-	5833.73 KB	1.473
Sylvan	50000	82.08 ms	94.723 ms	14.658 ms	5.72	0.91	-	10726.71 KB	2.709
SylvanAsync	50000	78.45 ms	2.021 ms	0.313 ms	5.47	0.02	-	10727.74 KB	2.709

ExcelReader.Benchmarks.ReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 3.19GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
ExcelReader	50000	11.916 ms	0.0680 ms	0.0105 ms	1.00	0.00	-	3.73 KB	1.00
ExcelReaderAsync	50000	12.400 ms	0.1378 ms	0.0213 ms	1.04	0.00	-	3.8 KB	1.02
ExcelReaderXlsb	50000	7.270 ms	0.0250 ms	0.0065 ms	0.61	0.00	-	4.05 KB	1.08
ExcelReaderXlsbAsync	50000	7.402 ms	0.1075 ms	0.0279 ms	0.62	0.00	-	4.12 KB	1.10
ExcelReaderMaterialized	50000	13.284 ms	0.0819 ms	0.0213 ms	1.11	0.00	93.7500	1615.06 KB	432.49
Sylvan	50000	55.244 ms	1.3595 ms	0.2104 ms	4.64	0.02	-	1939.18 KB	519.28
OfficeIMO	50000	203.650 ms	264.4153 ms	40.9186 ms	17.09	3.07	-	7003.97 KB	1,875.54
OfficeIMOXlsb	50000	17.675 ms	0.3864 ms	0.0598 ms	1.48	0.00	406.2500	6858.72 KB	1,836.64

ExcelReader.Benchmarks.RealDataReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
Xlsx_ExcelReader	76.623 ms	1.3756 ms	0.2129 ms	1.00	0.00	-	7720 B	1.00
Xlsx_Sylvan	311.419 ms	22.7511 ms	3.5208 ms	4.06	0.04	-	659568 B	85.44
Xlsx_ExcelReader_Materialized	77.948 ms	0.9473 ms	0.1466 ms	1.02	0.00	-	17416 B	2.26
Xlsx_ExcelReader_Prefetch	52.214 ms	11.8649 ms	3.0813 ms	0.68	0.04	-	26852 B	3.48
Xlsx_ExcelReader_Memory	77.592 ms	0.8782 ms	0.1359 ms	1.01	0.00	-	7464 B	0.97
Xlsx_ExcelReader_Memory_Prefetch	51.987 ms	22.3976 ms	5.8166 ms	0.68	0.07	-	26908 B	3.49
Xlsm_ExcelReader	77.794 ms	0.8965 ms	0.2328 ms	1.02	0.00	-	7720 B	1.00
Xlsm_Sylvan	310.297 ms	5.0602 ms	1.3141 ms	4.05	0.02	-	659648 B	85.45
Xlsm_ExcelReader_Materialized	77.874 ms	0.7616 ms	0.1978 ms	1.02	0.00	-	17416 B	2.26
Xlsm_ExcelReader_Prefetch	50.457 ms	22.5951 ms	3.4966 ms	0.66	0.04	-	27962 B	3.62
Xlsm_ExcelReader_Memory	76.066 ms	0.3553 ms	0.0923 ms	0.99	0.00	-	7464 B	0.97
Xlsm_ExcelReader_Memory_Prefetch	46.903 ms	4.8716 ms	1.2651 ms	0.61	0.02	-	27426 B	3.55
Xlsb_ExcelReader	34.657 ms	0.2941 ms	0.0455 ms	0.45	0.00	-	7264 B	0.94
Xlsb_Sylvan	42.360 ms	0.2748 ms	0.0714 ms	0.55	0.00	-	346673 B	44.91
Xlsb_ExcelReader_Materialized	36.615 ms	0.4287 ms	0.0663 ms	0.48	0.00	-	16960 B	2.20
Xlsb_ExcelReader_Prefetch	21.407 ms	3.2100 ms	0.8336 ms	0.28	0.01	-	27473 B	3.56
Xlsb_ExcelReader_Memory	34.664 ms	0.1992 ms	0.0308 ms	0.45	0.00	-	9008 B	1.17
Xlsb_ExcelReader_Memory_Prefetch	22.041 ms	2.0007 ms	0.3096 ms	0.29	0.00	-	18254 B	2.36
Xls_ExcelReader	16.060 ms	0.1071 ms	0.0278 ms	0.21	0.00	-	12216 B	1.58
Xls_Sylvan	25.543 ms	0.4191 ms	0.1088 ms	0.33	0.00	-	190366 B	24.66
Xls_ExcelReader_Materialized	18.268 ms	0.0629 ms	0.0097 ms	0.24	0.00	-	21912 B	2.84
Xls_ExcelReader_Memory	15.556 ms	0.1738 ms	0.0269 ms	0.20	0.00	-	12080 B	1.56
Csv_ExcelReader	8.334 ms	0.0406 ms	0.0063 ms	0.11	0.00	-	784 B	0.10
Csv_Sylvan	6.833 ms	0.0811 ms	0.0211 ms	0.09	0.00	-	41226 B	5.34
Csv_ExcelReader_Materialized	32.940 ms	0.3277 ms	0.0851 ms	0.43	0.00	1437.5000	37443392 B	4,850.18
Csv_ExcelReader_Memory	7.664 ms	0.1114 ms	0.0289 ms	0.10	0.00	-	512 B	0.07

ExcelReader.Benchmarks.RealDataTypedParseBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Ratio	Gen0	Allocated	Alloc Ratio
Xlsx_ExcelParser	89.70 ms	0.956 ms	0.148 ms	1.00	333.3333	8.02 MB	1.00
Xlsb_ExcelParser	45.54 ms	0.449 ms	0.117 ms	0.51	272.7273	8.02 MB	1.00

ExcelReader.Benchmarks.RecordWriteBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
Xlsx	50000	17.620 ms	0.9798 ms	0.2545 ms	1.00	0.02	500.0000	500.0000	500.0000	4.02 MB	1.00
Xlsb	50000	11.297 ms	0.3082 ms	0.0800 ms	0.64	0.01	500.0000	500.0000	500.0000	4.02 MB	1.00
Xls	50000	8.233 ms	0.6094 ms	0.1583 ms	0.47	0.01	250.0000	250.0000	250.0000	4.03 MB	1.00
Csv	50000	6.688 ms	0.0535 ms	0.0139 ms	0.38	0.01	500.0000	500.0000	500.0000	4 MB	1.00
XlsxMapped	50000	18.528 ms	0.3185 ms	0.0827 ms	1.05	0.01	500.0000	500.0000	500.0000	4.02 MB	1.00
XlsbMapped	50000	12.139 ms	0.2471 ms	0.0382 ms	0.69	0.01	500.0000	500.0000	500.0000	4.02 MB	1.00
CsvMapped	50000	8.757 ms	0.0978 ms	0.0254 ms	0.50	0.01	500.0000	500.0000	500.0000	4 MB	1.00

ExcelReader.Benchmarks.StringHeavyReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
Xlsx_ExcelReader	65536	40.77 ms	2.000 ms	0.310 ms	1.00	0.01	-	-	-	2.18 MB	1.00
Xlsx_ExcelReader_Prefetch	65536	33.82 ms	2.274 ms	0.591 ms	0.83	0.01	-	-	-	2.27 MB	1.04
Xlsx_Sylvan	65536	189.03 ms	6.842 ms	1.777 ms	4.64	0.05	666.6667	333.3333	-	17.41 MB	7.98
Xlsx_ExcelReader_Materialized	65536	61.91 ms	3.108 ms	0.807 ms	1.52	0.02	1000.0000	875.0000	250.0000	15.25 MB	6.99
Xlsx_ExcelReader_Materialized_Interned	65536	63.77 ms	7.944 ms	2.063 ms	1.56	0.05	1000.0000	875.0000	250.0000	15.26 MB	7.00
Xlsb_ExcelReader	65536	35.91 ms	1.250 ms	0.193 ms	0.88	0.01	-	-	-	2.18 MB	1.00
Xlsb_ExcelReader_Prefetch	65536	26.53 ms	1.298 ms	0.337 ms	0.65	0.01	-	-	-	2.31 MB	1.06
Xlsb_Sylvan	65536	59.23 ms	11.118 ms	2.887 ms	1.45	0.07	1111.1111	1000.0000	333.3333	17.38 MB	7.97
Xlsb_ExcelReader_Materialized	65536	55.04 ms	4.139 ms	0.641 ms	1.35	0.02	1100.0000	1000.0000	300.0000	15.25 MB	6.99
Xlsb_ExcelReader_Materialized_Interned	65536	55.58 ms	5.176 ms	1.344 ms	1.36	0.03	1100.0000	1000.0000	300.0000	15.26 MB	7.00
Xlsb_ExcelReader_Memory	65536	35.11 ms	1.182 ms	0.183 ms	0.86	0.01	-	-	-	6.47 MB	2.97

ExcelReader.Benchmarks.WriteBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
ExcelReaderWriter	50000	16.508 ms	0.1546 ms	0.0401 ms	1.00	0.00	500.0000	500.0000	500.0000	4.02 MB	1.00
ExcelReaderWriterSharedStrings	50000	16.050 ms	0.2038 ms	0.0529 ms	0.97	0.00	500.0000	500.0000	500.0000	4.06 MB	1.01
ExcelReaderWriterPrefetch	50000	12.320 ms	2.6839 ms	0.6970 ms	0.75	0.04	484.3750	484.3750	484.3750	4.03 MB	1.00
ExcelReaderXlsbWriter	50000	10.434 ms	0.2605 ms	0.0403 ms	0.63	0.00	500.0000	500.0000	500.0000	4.02 MB	1.00
ExcelReaderXlsbWriterSharedStrings	50000	10.302 ms	0.1938 ms	0.0300 ms	0.62	0.00	500.0000	500.0000	500.0000	4.06 MB	1.01
ExcelReaderXlsbWriterPrefetch	50000	9.403 ms	0.9702 ms	0.2520 ms	0.57	0.01	484.3750	484.3750	484.3750	4.03 MB	1.00
OfficeIMO	50000	24.467 ms	0.4918 ms	0.1277 ms	1.48	0.01	312.5000	312.5000	312.5000	4.02 MB	1.00
SpreadCheetah	50000	21.526 ms	0.7055 ms	0.1832 ms	1.30	0.01	1437.5000	718.7500	718.7500	15.84 MB	3.94

ExcelReader.Benchmarks.WritePathBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Mean	Error	StdDev	Allocated
NativeStrings_Xlsx	28.076 ms	0.2023 ms	0.0313 ms	18448 B
NativeStrings_Csv	7.399 ms	0.0922 ms	0.0240 ms	416 B
ArrowStrings_Xlsx	36.424 ms	0.8572 ms	0.2226 ms	18496 B
StyledRows_Xlsx	10.294 ms	0.1763 ms	0.0458 ms	18632 B

ExcelReader.Benchmarks.XlsReadBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 3.19GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	Gen0	Gen1	Allocated	Alloc Ratio
ExcelReader	50000	5.449 ms	0.1054 ms	0.0274 ms	1.00	-	-	2.75 KB	1.00
ExcelReaderAsync	50000	4.922 ms	0.0394 ms	0.0102 ms	0.90	-	-	2.82 KB	1.03
Sylvan	50000	8.953 ms	0.0864 ms	0.0224 ms	1.64	93.7500	15.6250	1717.73 KB	624.63
OfficeIMO	50000	10.396 ms	0.1577 ms	0.0244 ms	1.91	640.6250	-	10499.25 KB	3,817.91

ExcelReader.Benchmarks.XlsWriteBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
XlsWriter	50000	8.375 ms	0.1838 ms	0.0477 ms	1.00	484.3750	484.3750	484.3750	16.03 MB	1.00
XlsxWriter	50000	16.594 ms	0.6382 ms	0.0988 ms	1.98	500.0000	500.0000	500.0000	4.02 MB	0.25

ExcelReader.Benchmarks.XlsxSharedStringHotPathBenchmark


BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 9V45 2.60GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4
  Job-MEHJPP : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v4

IterationCount=5  WarmupCount=1

Method	Rows	Mean	Error	StdDev	Ratio	RatioSD	Allocated	Alloc Ratio
EndToEnd	65536	40.782 ms	1.9189 ms	0.2970 ms	1.00	0.01	2285968 B	1.00
EndToEnd_Prefetch	65536	34.020 ms	3.5101 ms	0.9116 ms	0.83	0.02	2382275 B	1.04
SharedStringPrologue	65536	15.833 ms	0.1874 ms	0.0487 ms	0.39	0.00	765104 B	0.33
Stored_EndToEnd	65536	17.950 ms	0.2507 ms	0.0651 ms	0.44	0.00	2284888 B	1.00
Stored_SharedStringPrologue	65536	4.130 ms	0.1627 ms	0.0252 ms	0.10	0.00	764024 B	0.33
IndexParse_Utf8Parser	65536	2.227 ms	0.2182 ms	0.0567 ms	0.05	0.00	-	0.00
IndexParse_DigitLoop	65536	1.323 ms	0.0461 ms	0.0120 ms	0.03	0.00	-	0.00

GabrielMarquezMatte and others added 29 commits October 5, 2026 15:21

feat: enhance support for various Arrow types and improve handling of…

8379db3

… empty rows in readers

feat(core): add ByteSource, a positional view over memory, files and …

74050b3

…seekable streams Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

feat(core): add ByteSourceStream, a buffered range stream over a Byte…

a3a3752

…Source Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

refactor(core): rename ZipMemoryIndex to ZipIndex and index names int…

702e21a

…o the central directory Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

feat(core): let ZipIndex read its directory and entries through any B…

40b7a04

…yteSource Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

fix(core): reject stored ZIP entries whose sizes disagree

5f79408

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

refactor(core): read XLSX from streams and files through ZipIndex

9492ec3

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

refactor(core): read XLSB from streams and files through ZipIndex

676d146

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

refactor(core): load XLS sectors through ByteSource instead of seekin…

fc38fdf

…g a shared stream Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

fix(core): accept bytes after the ZIP end-of-central-directory record

696134e

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

fix(core): restore stream position on failed detection and wrap only …

fd30186

…exact stream types Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

test(core): make the inverting MemoryStream subclass not recurse

d408b0f

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

feat(core): load XLSX shared strings once and keep the reader alive f…

1e49a2b

…or its enumerators Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

feat(core): keep an XLSB reader alive for its enumerators

fecefc4

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

feat(core): keep an XLS reader alive for its enumerators

c8dbaa6

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

test(core): cancel an XLSX shared-string load and load again

ea28790

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

fix(core): offer no raw chunk source for a transcoded CSV file

ea85fef

A FileStream opened with a non-UTF-8 encoding would hand parallel chunking the raw, untranscoded file. The only caller already filters on encoding, so this was latent. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Merge branch 'master' into develop

1723f07

GabrielMarquezMatte merged commit 1161344 into master Oct 6, 2026
57 checks passed

Conversation

GabrielMarquezMatte commented Oct 6, 2026

What does this change?

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codecov-commenter commented Oct 6, 2026

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github-actions Bot commented Oct 6, 2026

Benchmark Results

Moved by at least 10%

ExcelReader.Benchmarks.ArrowConversionBenchmark

ExcelReader.Benchmarks.ChunkedParseBenchmark

ExcelReader.Benchmarks.ColdStartBenchmark

ExcelReader.Benchmarks.CsvParallelParseBenchmark

ExcelReader.Benchmarks.CsvParallelVsSepBenchmark

ExcelReader.Benchmarks.CsvParseBenchmark

ExcelReader.Benchmarks.CsvReadBenchmark

ExcelReader.Benchmarks.CsvWriteBenchmark

ExcelReader.Benchmarks.DataReaderBenchmark

ExcelReader.Benchmarks.EncryptedWorkbookBenchmark

ExcelReader.Benchmarks.NativeRowReadBenchmark

ExcelReader.Benchmarks.NativeTypedParseBenchmark

ExcelReader.Benchmarks.ParseBenchmark

ExcelReader.Benchmarks.ReadBenchmark

ExcelReader.Benchmarks.RealDataReadBenchmark

ExcelReader.Benchmarks.RealDataTypedParseBenchmark

ExcelReader.Benchmarks.RecordWriteBenchmark

ExcelReader.Benchmarks.StringHeavyReadBenchmark

ExcelReader.Benchmarks.WriteBenchmark

ExcelReader.Benchmarks.WritePathBenchmark

ExcelReader.Benchmarks.XlsReadBenchmark

ExcelReader.Benchmarks.XlsWriteBenchmark

ExcelReader.Benchmarks.XlsxSharedStringHotPathBenchmark

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