From 3d0b335b0fa5fcde7562a6c4c8c4ae84e70a81f0 Mon Sep 17 00:00:00 2001
From: Qingyang Hu <qingyang.hu@mongodb.com>
Date: Fri, 22 May 2026 22:22:13 -0400
Subject: [PATCH 1/4] GODRIVER-3868 Update extended bson cases.

---
 bson/benchmark_test.go                   | 116 +++++++++++++----------
 internal/cmd/benchmark/benchmark_test.go |  52 +++++++++-
 testdata/extended_bson/deep_bson.json.gz | Bin 616 -> 0 bytes
 testdata/extended_bson/flat_bson.json.gz | Bin 5078 -> 0 bytes
 testdata/extended_bson/full_bson.json.gz | Bin 3345 -> 0 bytes
 5 files changed, 118 insertions(+), 50 deletions(-)
 delete mode 100644 testdata/extended_bson/deep_bson.json.gz
 delete mode 100644 testdata/extended_bson/flat_bson.json.gz
 delete mode 100644 testdata/extended_bson/full_bson.json.gz

diff --git a/bson/benchmark_test.go b/bson/benchmark_test.go
index 991714eb65..ebb437f96d 100644
--- a/bson/benchmark_test.go
+++ b/bson/benchmark_test.go
@@ -7,14 +7,14 @@
 package bson
 
 import (
+	"archive/tar"
 	"bytes"
 	"compress/gzip"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
-	"path"
 	"sync"
 	"testing"
 )
@@ -144,54 +144,74 @@ var nestedInstance = nestedtest1{
 	},
 }
 
-const extendedBSONDir = "../testdata/extended_bson"
+const extendedBSONTGZ = "../testdata/specifications/source/benchmarking/data/extended_bson.tgz"
 
 var (
 	extJSONFiles   map[string]map[string]any
 	extJSONFilesMu sync.Mutex
 )
 
-// readExtJSONFile reads the GZIP-compressed extended JSON document from the given filename in the
-// "extended BSON" test data directory (../testdata/extended_bson) and returns it as a
-// map[string]any. It panics on any errors.
-func readExtJSONFile(filename string) map[string]any {
+// readExtJSONFile reads the named JSON file from the extended_bson.tgz archive and returns it as a
+// map[string]any. The first call decompresses the archive and caches all entries; subsequent calls
+// only look up the cache. It calls b.Fatal on any errors.
+func readExtJSONFile(b *testing.B, filename string) map[string]any {
+	b.Helper()
 	extJSONFilesMu.Lock()
 	defer extJSONFilesMu.Unlock()
-	if v, ok := extJSONFiles[filename]; ok {
-		return v
-	}
-	filePath := path.Join(extendedBSONDir, filename)
-	file, err := os.Open(filePath)
-	if err != nil {
-		panic(fmt.Sprintf("error opening file %q: %s", filePath, err))
-	}
-	defer func() {
-		_ = file.Close()
-	}()
 
-	gz, err := gzip.NewReader(file)
-	if err != nil {
-		panic(fmt.Sprintf("error creating GZIP reader: %s", err))
-	}
-	defer func() {
-		_ = gz.Close()
-	}()
+	if extJSONFiles == nil {
+		file, err := os.Open(extendedBSONTGZ)
+		if err != nil {
+			b.Fatalf("error opening %q: %s", extendedBSONTGZ, err)
+			return nil
+		}
+		defer func() {
+			_ = file.Close()
+		}()
+
+		gz, err := gzip.NewReader(file)
+		if err != nil {
+			b.Fatalf("error creating gzip reader: %s", err)
+			return nil
+		}
+		defer func() {
+			_ = gz.Close()
+		}()
 
-	data, err := ioutil.ReadAll(gz)
-	if err != nil {
-		panic(fmt.Sprintf("error reading GZIP contents of file: %s", err))
-	}
+		extJSONFiles = make(map[string]map[string]any)
 
-	var v map[string]any
-	err = UnmarshalExtJSON(data, false, &v)
-	if err != nil {
-		panic(fmt.Sprintf("error unmarshalling extended JSON: %s", err))
+		tr := tar.NewReader(gz)
+		for {
+			hdr, err := tr.Next()
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			if err != nil {
+				b.Fatalf("error reading tar: %s", err)
+				return nil
+			}
+			if hdr.Typeflag != tar.TypeReg {
+				continue
+			}
+			data, err := io.ReadAll(tr)
+			if err != nil {
+				b.Fatalf("error reading tar entry %q: %s", hdr.Name, err)
+				return nil
+			}
+			var v map[string]any
+			if err = UnmarshalExtJSON(data, false, &v); err != nil {
+				b.Fatalf("error unmarshalling %q: %s", hdr.Name, err)
+				return nil
+			}
+			extJSONFiles[hdr.Name] = v
+		}
 	}
 
-	if extJSONFiles == nil {
-		extJSONFiles = make(map[string]map[string]any)
+	v, ok := extJSONFiles["extended_bson/"+filename]
+	if !ok {
+		b.Fatalf("file %q not found in %q", filename, extendedBSONTGZ)
+		return nil
 	}
-	extJSONFiles[filename] = v
 	return v
 }
 
@@ -213,16 +233,16 @@ func BenchmarkMarshal(b *testing.B) {
 			value: encodetestBsonD,
 		},
 		{
-			desc:  "deep_bson.json.gz",
-			value: readExtJSONFile("deep_bson.json.gz"),
+			desc:  "deep_bson.json",
+			value: readExtJSONFile(b, "deep_bson.json"),
 		},
 		{
-			desc:  "flat_bson.json.gz",
-			value: readExtJSONFile("flat_bson.json.gz"),
+			desc:  "flat_bson.json",
+			value: readExtJSONFile(b, "flat_bson.json"),
 		},
 		{
-			desc:  "full_bson.json.gz",
-			value: readExtJSONFile("full_bson.json.gz"),
+			desc:  "full_bson.json",
+			value: readExtJSONFile(b, "full_bson.json"),
 		},
 	}
 
@@ -314,16 +334,16 @@ func BenchmarkUnmarshal(b *testing.B) {
 			value: nestedInstance,
 		},
 		{
-			name:  "deep_bson.json.gz",
-			value: readExtJSONFile("deep_bson.json.gz"),
+			name:  "deep_bson.json",
+			value: readExtJSONFile(b, "deep_bson.json"),
 		},
 		{
-			name:  "flat_bson.json.gz",
-			value: readExtJSONFile("flat_bson.json.gz"),
+			name:  "flat_bson.json",
+			value: readExtJSONFile(b, "flat_bson.json"),
 		},
 		{
-			name:  "full_bson.json.gz",
-			value: readExtJSONFile("full_bson.json.gz"),
+			name:  "full_bson.json",
+			value: readExtJSONFile(b, "full_bson.json"),
 		},
 	}
 
diff --git a/internal/cmd/benchmark/benchmark_test.go b/internal/cmd/benchmark/benchmark_test.go
index 3e0ba80dce..cfd6d40b7d 100644
--- a/internal/cmd/benchmark/benchmark_test.go
+++ b/internal/cmd/benchmark/benchmark_test.go
@@ -209,8 +209,56 @@ func loadSourceDocument(b *testing.B, canonicalOnly bool, pathParts ...string) b
 	return doc
 }
 
+func loadBSONExtJSONFile(b *testing.B, canonicalOnly bool, source string) bson.D {
+	b.Helper()
+
+	tgzPath := filepath.Join(testdataDir(b), "specifications", "source", "benchmarking", "data", "extended_bson.tgz")
+
+	file, err := os.Open(tgzPath)
+	require.NoError(b, err, "failed to open %q", tgzPath)
+	defer file.Close()
+
+	gz, err := gzip.NewReader(file)
+	require.NoError(b, err, "failed to create gzip reader")
+	defer gz.Close()
+
+	tr := tar.NewReader(gz)
+	for {
+		hdr, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+
+		require.NoError(b, err, "failed to read tar")
+
+		if hdr.Typeflag != tar.TypeReg {
+			continue
+		}
+
+		if hdr.Name != bsonDataDir+"/"+source {
+			continue
+		}
+
+		data, err := io.ReadAll(tr)
+		require.NoError(b, err, "failed to read tar entry %q", hdr.Name)
+
+		var doc bson.D
+
+		err = bson.UnmarshalExtJSON(data, canonicalOnly, &doc)
+		require.NoError(b, err, "failed to unmarshal extended JSON from %q", hdr.Name)
+
+		require.NotEmpty(b, doc)
+
+		return doc
+	}
+
+	b.Fatalf("file %q not found in %q", bsonDataDir+"/"+source, tgzPath)
+
+	return nil
+}
+
 func benchmarkBSONEncoding(b *testing.B, canonicalOnly bool, source string) {
-	doc := loadSourceDocument(b, canonicalOnly, testdataPerfDir(b), bsonDataDir, source)
+	doc := loadBSONExtJSONFile(b, canonicalOnly, source)
 
 	b.ResetTimer()
 
@@ -229,7 +277,7 @@ func benchmarkBSONEncoding(b *testing.B, canonicalOnly bool, source string) {
 }
 
 func benchmarkBSONDecoding(b *testing.B, canonicalOnly bool, source string) {
-	doc := loadSourceDocument(b, canonicalOnly, testdataPerfDir(b), bsonDataDir, source)
+	doc := loadBSONExtJSONFile(b, canonicalOnly, source)
 
 	raw, err := bson.Marshal(doc)
 	require.NoError(b, err, "failed to encode bson data")
diff --git a/testdata/extended_bson/deep_bson.json.gz b/testdata/extended_bson/deep_bson.json.gz
deleted file mode 100644
index e2588ef533a525d215b0dd604e087565f68fb53d..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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diff --git a/testdata/extended_bson/flat_bson.json.gz b/testdata/extended_bson/flat_bson.json.gz
deleted file mode 100644
index 124148bf67162d2a58f75312a92121a8aa304230..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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diff --git a/testdata/extended_bson/full_bson.json.gz b/testdata/extended_bson/full_bson.json.gz
deleted file mode 100644
index afd5b59f99e7ed34dec3dc5635760fcb7d743094..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 3345
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From 009755fb1861bc6c1287899ac38e51c8ffda02b6 Mon Sep 17 00:00:00 2001
From: Qingyang Hu <qingyang.hu@mongodb.com>
Date: Mon, 1 Jun 2026 23:18:28 -0400
Subject: [PATCH 2/4] rewrite with sync.Once

---
 bson/benchmark_test.go | 141 ++++++++++++++++++++++-------------------
 1 file changed, 75 insertions(+), 66 deletions(-)

diff --git a/bson/benchmark_test.go b/bson/benchmark_test.go
index ebb437f96d..0f4f887839 100644
--- a/bson/benchmark_test.go
+++ b/bson/benchmark_test.go
@@ -17,6 +17,8 @@ import (
 	"os"
 	"sync"
 	"testing"
+
+	"go.mongodb.org/mongo-driver/v2/internal/require"
 )
 
 var encodetestBsonD D
@@ -144,76 +146,83 @@ var nestedInstance = nestedtest1{
 	},
 }
 
-const extendedBSONTGZ = "../testdata/specifications/source/benchmarking/data/extended_bson.tgz"
+// loadExtendedBSON is a function that returns the extended BSON data for a given filename in the
+// extended_bson.tgz archive. The first call to loadExtendedBSON will decompress all the JSON files
+// in the archive and cache all entries; subsequent calls will only return the cache. Caller must
+// not mutate the returned value.
+var loadExtendedBSON = func() func(tb testing.TB, filename string) map[string]any {
+	const extendedBSONTGZ = "../testdata/specifications/source/benchmarking/data/extended_bson.tgz"
 
-var (
-	extJSONFiles   map[string]map[string]any
-	extJSONFilesMu sync.Mutex
-)
+	var once sync.Once
+	var onceErr error
+	entryErr := make(map[string]error)
+	results := make(map[string]map[string]any)
 
-// readExtJSONFile reads the named JSON file from the extended_bson.tgz archive and returns it as a
-// map[string]any. The first call decompresses the archive and caches all entries; subsequent calls
-// only look up the cache. It calls b.Fatal on any errors.
-func readExtJSONFile(b *testing.B, filename string) map[string]any {
-	b.Helper()
-	extJSONFilesMu.Lock()
-	defer extJSONFilesMu.Unlock()
-
-	if extJSONFiles == nil {
-		file, err := os.Open(extendedBSONTGZ)
-		if err != nil {
-			b.Fatalf("error opening %q: %s", extendedBSONTGZ, err)
-			return nil
-		}
-		defer func() {
-			_ = file.Close()
-		}()
-
-		gz, err := gzip.NewReader(file)
-		if err != nil {
-			b.Fatalf("error creating gzip reader: %s", err)
-			return nil
-		}
-		defer func() {
-			_ = gz.Close()
-		}()
-
-		extJSONFiles = make(map[string]map[string]any)
+	return func(tb testing.TB, filename string) map[string]any {
+		tb.Helper()
 
-		tr := tar.NewReader(gz)
-		for {
-			hdr, err := tr.Next()
-			if errors.Is(err, io.EOF) {
-				break
-			}
+		once.Do(func() {
+			file, err := os.Open(extendedBSONTGZ)
 			if err != nil {
-				b.Fatalf("error reading tar: %s", err)
-				return nil
-			}
-			if hdr.Typeflag != tar.TypeReg {
-				continue
+				onceErr = fmt.Errorf("error opening %q: %v", extendedBSONTGZ, err)
+				return
 			}
-			data, err := io.ReadAll(tr)
+			defer func() {
+				_ = file.Close()
+			}()
+
+			gz, err := gzip.NewReader(file)
 			if err != nil {
-				b.Fatalf("error reading tar entry %q: %s", hdr.Name, err)
-				return nil
+				onceErr = fmt.Errorf("error creating gzip reader: %v", err)
+				return
+			}
+			defer func() {
+				_ = gz.Close()
+			}()
+
+			tr := tar.NewReader(gz)
+			for {
+				hdr, err := tr.Next()
+				if errors.Is(err, io.EOF) {
+					break
+				}
+				if err != nil {
+					onceErr = fmt.Errorf("error reading tar header: %v", err)
+					return
+				}
+				if hdr.Typeflag != tar.TypeReg {
+					continue
+				}
+				data, err := io.ReadAll(tr)
+				if err != nil {
+					entryErr[hdr.Name] = fmt.Errorf("error reading tar entry: %v", err)
+					continue
+				}
+
+				var v map[string]any
+				err = UnmarshalExtJSON(data, false, &v)
+				if err != nil {
+					entryErr[hdr.Name] = fmt.Errorf("error unmarshalling: %v", err)
+					continue
+				}
+				results[hdr.Name] = v
 			}
-			var v map[string]any
-			if err = UnmarshalExtJSON(data, false, &v); err != nil {
-				b.Fatalf("error unmarshalling %q: %s", hdr.Name, err)
-				return nil
+		})
+		entry := "extended_bson/" + filename
+		if err, ok := entryErr[entry]; ok {
+			require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, err)
+		}
+		v, ok := results[entry]
+		if !ok {
+			if onceErr != nil {
+				require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, onceErr)
+			} else {
+				require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: not found", filename, extendedBSONTGZ)
 			}
-			extJSONFiles[hdr.Name] = v
 		}
+		return v
 	}
-
-	v, ok := extJSONFiles["extended_bson/"+filename]
-	if !ok {
-		b.Fatalf("file %q not found in %q", filename, extendedBSONTGZ)
-		return nil
-	}
-	return v
-}
+}()
 
 func BenchmarkMarshal(b *testing.B) {
 	cases := []struct {
@@ -234,15 +243,15 @@ func BenchmarkMarshal(b *testing.B) {
 		},
 		{
 			desc:  "deep_bson.json",
-			value: readExtJSONFile(b, "deep_bson.json"),
+			value: loadExtendedBSON(b, "deep_bson.json"),
 		},
 		{
 			desc:  "flat_bson.json",
-			value: readExtJSONFile(b, "flat_bson.json"),
+			value: loadExtendedBSON(b, "flat_bson.json"),
 		},
 		{
 			desc:  "full_bson.json",
-			value: readExtJSONFile(b, "full_bson.json"),
+			value: loadExtendedBSON(b, "full_bson.json"),
 		},
 	}
 
@@ -335,15 +344,15 @@ func BenchmarkUnmarshal(b *testing.B) {
 		},
 		{
 			name:  "deep_bson.json",
-			value: readExtJSONFile(b, "deep_bson.json"),
+			value: loadExtendedBSON(b, "deep_bson.json"),
 		},
 		{
 			name:  "flat_bson.json",
-			value: readExtJSONFile(b, "flat_bson.json"),
+			value: loadExtendedBSON(b, "flat_bson.json"),
 		},
 		{
 			name:  "full_bson.json",
-			value: readExtJSONFile(b, "full_bson.json"),
+			value: loadExtendedBSON(b, "full_bson.json"),
 		},
 	}
 

From b17879b752faedac8ce9a8f33ef99381406effca Mon Sep 17 00:00:00 2001
From: Qingyang Hu <qingyang.hu@mongodb.com>
Date: Mon, 1 Jun 2026 23:26:03 -0400
Subject: [PATCH 3/4] revert changes in
 internal/cmd/benchmark/benchmark_test.go

---
 internal/cmd/benchmark/benchmark_test.go | 52 +-----------------------
 1 file changed, 2 insertions(+), 50 deletions(-)

diff --git a/internal/cmd/benchmark/benchmark_test.go b/internal/cmd/benchmark/benchmark_test.go
index cfd6d40b7d..3e0ba80dce 100644
--- a/internal/cmd/benchmark/benchmark_test.go
+++ b/internal/cmd/benchmark/benchmark_test.go
@@ -209,56 +209,8 @@ func loadSourceDocument(b *testing.B, canonicalOnly bool, pathParts ...string) b
 	return doc
 }
 
-func loadBSONExtJSONFile(b *testing.B, canonicalOnly bool, source string) bson.D {
-	b.Helper()
-
-	tgzPath := filepath.Join(testdataDir(b), "specifications", "source", "benchmarking", "data", "extended_bson.tgz")
-
-	file, err := os.Open(tgzPath)
-	require.NoError(b, err, "failed to open %q", tgzPath)
-	defer file.Close()
-
-	gz, err := gzip.NewReader(file)
-	require.NoError(b, err, "failed to create gzip reader")
-	defer gz.Close()
-
-	tr := tar.NewReader(gz)
-	for {
-		hdr, err := tr.Next()
-		if errors.Is(err, io.EOF) {
-			break
-		}
-
-		require.NoError(b, err, "failed to read tar")
-
-		if hdr.Typeflag != tar.TypeReg {
-			continue
-		}
-
-		if hdr.Name != bsonDataDir+"/"+source {
-			continue
-		}
-
-		data, err := io.ReadAll(tr)
-		require.NoError(b, err, "failed to read tar entry %q", hdr.Name)
-
-		var doc bson.D
-
-		err = bson.UnmarshalExtJSON(data, canonicalOnly, &doc)
-		require.NoError(b, err, "failed to unmarshal extended JSON from %q", hdr.Name)
-
-		require.NotEmpty(b, doc)
-
-		return doc
-	}
-
-	b.Fatalf("file %q not found in %q", bsonDataDir+"/"+source, tgzPath)
-
-	return nil
-}
-
 func benchmarkBSONEncoding(b *testing.B, canonicalOnly bool, source string) {
-	doc := loadBSONExtJSONFile(b, canonicalOnly, source)
+	doc := loadSourceDocument(b, canonicalOnly, testdataPerfDir(b), bsonDataDir, source)
 
 	b.ResetTimer()
 
@@ -277,7 +229,7 @@ func benchmarkBSONEncoding(b *testing.B, canonicalOnly bool, source string) {
 }
 
 func benchmarkBSONDecoding(b *testing.B, canonicalOnly bool, source string) {
-	doc := loadBSONExtJSONFile(b, canonicalOnly, source)
+	doc := loadSourceDocument(b, canonicalOnly, testdataPerfDir(b), bsonDataDir, source)
 
 	raw, err := bson.Marshal(doc)
 	require.NoError(b, err, "failed to encode bson data")

From 9b37a70c7ed1b4931ce8d0cb037caed3220b6e58 Mon Sep 17 00:00:00 2001
From: Qingyang Hu <qingyang.hu@mongodb.com>
Date: Wed, 3 Jun 2026 15:53:42 -0400
Subject: [PATCH 4/4] Use global variables to replace closure.

---
 bson/benchmark_test.go | 121 +++++++++++++++++++++--------------------
 1 file changed, 62 insertions(+), 59 deletions(-)

diff --git a/bson/benchmark_test.go b/bson/benchmark_test.go
index 0f4f887839..045cc5f558 100644
--- a/bson/benchmark_test.go
+++ b/bson/benchmark_test.go
@@ -146,83 +146,86 @@ var nestedInstance = nestedtest1{
 	},
 }
 
+var (
+	loadExtendedBSONOnce      sync.Once
+	loadExtendedBSONErr       error
+	loadExtendedBSONEntries   map[string]map[string]any
+	loadExtendedBSONEntryErrs map[string]error
+)
+
 // loadExtendedBSON is a function that returns the extended BSON data for a given filename in the
 // extended_bson.tgz archive. The first call to loadExtendedBSON will decompress all the JSON files
 // in the archive and cache all entries; subsequent calls will only return the cache. Caller must
 // not mutate the returned value.
-var loadExtendedBSON = func() func(tb testing.TB, filename string) map[string]any {
+func loadExtendedBSON(tb testing.TB, filename string) map[string]any {
+	tb.Helper()
+
 	const extendedBSONTGZ = "../testdata/specifications/source/benchmarking/data/extended_bson.tgz"
 
-	var once sync.Once
-	var onceErr error
-	entryErr := make(map[string]error)
-	results := make(map[string]map[string]any)
+	loadExtendedBSONOnce.Do(func() {
+		file, err := os.Open(extendedBSONTGZ)
+		if err != nil {
+			loadExtendedBSONErr = fmt.Errorf("error opening %q: %v", extendedBSONTGZ, err)
+			return
+		}
+		defer func() {
+			_ = file.Close()
+		}()
+
+		gz, err := gzip.NewReader(file)
+		if err != nil {
+			loadExtendedBSONErr = fmt.Errorf("error creating gzip reader: %v", err)
+			return
+		}
+		defer func() {
+			_ = gz.Close()
+		}()
 
-	return func(tb testing.TB, filename string) map[string]any {
-		tb.Helper()
+		loadExtendedBSONEntries = make(map[string]map[string]any)
+		loadExtendedBSONEntryErrs = make(map[string]error)
 
-		once.Do(func() {
-			file, err := os.Open(extendedBSONTGZ)
+		tr := tar.NewReader(gz)
+		for {
+			hdr, err := tr.Next()
+			if errors.Is(err, io.EOF) {
+				break
+			}
 			if err != nil {
-				onceErr = fmt.Errorf("error opening %q: %v", extendedBSONTGZ, err)
+				loadExtendedBSONErr = fmt.Errorf("error reading tar header: %v", err)
 				return
 			}
-			defer func() {
-				_ = file.Close()
-			}()
-
-			gz, err := gzip.NewReader(file)
+			if hdr.Typeflag != tar.TypeReg {
+				continue
+			}
+			data, err := io.ReadAll(tr)
 			if err != nil {
-				onceErr = fmt.Errorf("error creating gzip reader: %v", err)
-				return
+				loadExtendedBSONEntryErrs[hdr.Name] = fmt.Errorf("error reading tar entry: %v", err)
+				continue
 			}
-			defer func() {
-				_ = gz.Close()
-			}()
-
-			tr := tar.NewReader(gz)
-			for {
-				hdr, err := tr.Next()
-				if errors.Is(err, io.EOF) {
-					break
-				}
-				if err != nil {
-					onceErr = fmt.Errorf("error reading tar header: %v", err)
-					return
-				}
-				if hdr.Typeflag != tar.TypeReg {
-					continue
-				}
-				data, err := io.ReadAll(tr)
-				if err != nil {
-					entryErr[hdr.Name] = fmt.Errorf("error reading tar entry: %v", err)
-					continue
-				}
 
-				var v map[string]any
-				err = UnmarshalExtJSON(data, false, &v)
-				if err != nil {
-					entryErr[hdr.Name] = fmt.Errorf("error unmarshalling: %v", err)
-					continue
-				}
-				results[hdr.Name] = v
+			var v map[string]any
+			err = UnmarshalExtJSON(data, false, &v)
+			if err != nil {
+				loadExtendedBSONEntryErrs[hdr.Name] = fmt.Errorf("error unmarshalling: %v", err)
+				continue
 			}
-		})
-		entry := "extended_bson/" + filename
-		if err, ok := entryErr[entry]; ok {
-			require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, err)
+			loadExtendedBSONEntries[hdr.Name] = v
 		}
-		v, ok := results[entry]
-		if !ok {
-			if onceErr != nil {
-				require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, onceErr)
-			} else {
-				require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: not found", filename, extendedBSONTGZ)
-			}
+	})
+	entry := "extended_bson/" + filename
+	if err, ok := loadExtendedBSONEntryErrs[entry]; ok {
+		require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, err)
+	}
+	v, ok := loadExtendedBSONEntries[entry]
+	if !ok {
+		if loadExtendedBSONErr != nil {
+			require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: %v", filename, extendedBSONTGZ, loadExtendedBSONErr)
+		} else {
+			require.FailNowf(tb, "failed to load benchmark data", "error loading file %q from %q: not found", filename, extendedBSONTGZ)
 		}
-		return v
 	}
-}()
+	return v
+}
 
 func BenchmarkMarshal(b *testing.B) {
 	cases := []struct {