go/opentelemetry-go
1
0
Fork 0
mirror of https://github.com/open-telemetry/opentelemetry-go.git synced 2025-08-10 22:31:50 +02:00
Code Issues Releases Activity

all: replace math/rand with math/rand/v2 (#6732)

Browse Source 
Update to new stdlib apis.

The new Float64 is uniform, which resolves a long comment.


https://cs.opensource.google/go/go/+/refs/tags/go1.24.2:src/math/rand/v2/rand.go;l=209

> // There are exactly 1<<53 float64s in [0,1). Use Intn(1<<53) /
(1<<53).
	return float64(r.Uint64()<<11>>11) / (1 << 53)

```
goos: linux
goarch: amd64
pkg: go.opentelemetry.io/otel/sdk/trace
cpu: 12th Gen Intel(R) Core(TM) i7-1260P
                                 │   old.txt    │               new.txt                │
                                 │    sec/op    │    sec/op     vs base                │
TraceStart/with_a_simple_span-16   387.1n ±  5%   306.8n ± 15%  -20.73% (p=0.000 n=10)
TraceStart/with_several_links-16   542.2n ±  5%   501.0n ±  2%   -7.61% (p=0.000 n=10)
TraceStart/with_attributes-16      521.4n ± 14%   571.6n ±  6%   +9.64% (p=0.009 n=10)
geomean                            478.3n         444.6n         -7.05%

                                 │  old.txt   │               new.txt               │
                                 │    B/op    │    B/op     vs base                 │
TraceStart/with_a_simple_span-16   528.0 ± 0%   528.0 ± 0%       ~ (p=1.000 n=10) ¹
TraceStart/with_several_links-16   704.0 ± 0%   704.0 ± 0%       ~ (p=1.000 n=10) ¹
TraceStart/with_attributes-16      784.0 ± 0%   784.0 ± 0%       ~ (p=1.000 n=10) ¹
geomean                            663.0        663.0       +0.00%
¹ all samples are equal

                                 │  old.txt   │               new.txt               │
                                 │ allocs/op  │ allocs/op   vs base                 │
TraceStart/with_a_simple_span-16   2.000 ± 0%   2.000 ± 0%       ~ (p=1.000 n=10) ¹
TraceStart/with_several_links-16   3.000 ± 0%   3.000 ± 0%       ~ (p=1.000 n=10) ¹
TraceStart/with_attributes-16      4.000 ± 0%   4.000 ± 0%       ~ (p=1.000 n=10) ¹
geomean                            2.884        2.884       +0.00%
¹ all samples are equal
```

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>
Co-authored-by: Damien Mathieu <42@dmathieu.com>
This commit is contained in:
Sean Liao
2025-05-15 08:21:49 +01:00
committed by GitHub
parent f410084b21
commit a571c52b0a
10 changed files with 41 additions and 71 deletions
Download Patch File Download Diff File Expand all files Collapse all files

36
sdk/metric/exemplar/fixed_size_reservoir.go
View File

@@ -6,7 +6,7 @@ package exemplar // import "go.opentelemetry.io/otel/sdk/metric/exemplar"
import (
"context"
"math"
"math/rand"
"math/rand/v2"
"time"
"go.opentelemetry.io/otel/attribute"
@@ -44,18 +44,11 @@ type FixedSizeReservoir struct {
// w is the largest random number in a distribution that is used to compute
// the next next.
w float64
// rng is used to make sampling decisions.
//
// Do not use crypto/rand. There is no reason for the decrease in performance
// given this is not a security sensitive decision.
rng *rand.Rand
}
func newFixedSizeReservoir(s *storage) *FixedSizeReservoir {
r := &FixedSizeReservoir{
storage: s,
rng: rand.New(rand.NewSource(time.Now().UnixNano())),
}
r.reset()
return r
@@ -64,26 +57,15 @@ func newFixedSizeReservoir(s *storage) *FixedSizeReservoir {
// randomFloat64 returns, as a float64, a uniform pseudo-random number in the
// open interval (0.0,1.0).
func (r *FixedSizeReservoir) randomFloat64() float64 {
// TODO: This does not return a uniform number. rng.Float64 returns a
// uniformly random int in [0,2^53) that is divided by 2^53. Meaning it
// returns multiples of 2^-53, and not all floating point numbers between 0
// and 1 (i.e. for values less than 2^-4 the 4 last bits of the significand
// are always going to be 0).
// TODO: Use an algorithm that avoids rejection sampling. For example:
//
// An alternative algorithm should be considered that will actually return
// a uniform number in the interval (0,1). For example, since the default
// rand source provides a uniform distribution for Int63, this can be
// converted following the prototypical code of Mersenne Twister 64 (Takuji
// Nishimura and Makoto Matsumoto:
// http://www.math.sci.hiroshima-u.ac.jp/m-mat/MT/VERSIONS/C-LANG/mt19937-64.c)
//
// (float64(rng.Int63()>>11) + 0.5) * (1.0 / 4503599627370496.0)
//
// There are likely many other methods to explore here as well.
f := r.rng.Float64()
// const precision = 1 << 53 // 2^53
// // Generate an integer in [1, 2^53 - 1]
// v := rand.Uint64() % (precision - 1) + 1
// return float64(v) / float64(precision)
f := rand.Float64()
for f == 0 {
f = r.rng.Float64()
f = rand.Float64()
}
return f
}
@@ -146,7 +128,7 @@ func (r *FixedSizeReservoir) Offer(ctx context.Context, t time.Time, n Value, a
} else {
if r.count == r.next {
// Overwrite a random existing measurement with the one offered.
idx := int(r.rng.Int63n(int64(cap(r.store))))
idx := int(rand.Int64N(int64(cap(r.store))))
r.store[idx] = newMeasurement(ctx, t, n, a)
r.advance()
}

8
sdk/metric/exemplar/fixed_size_reservoir_test.go
View File

@@ -6,10 +6,9 @@ package exemplar
import (
"context"
"math"
"math/rand"
"math/rand/v2"
"slices"
"testing"
"time"
"github.com/stretchr/testify/assert"
)
@@ -28,7 +27,10 @@ func TestNewFixedSizeReservoirSamplingCorrectness(t *testing.T) {
intensity := 0.1
sampleSize := 1000
rng := rand.New(rand.NewSource(time.Now().UnixNano()))
u := rand.Uint32()
seed := [32]byte{byte(u), byte(u >> 8), byte(u >> 16), byte(u >> 24)}
t.Logf("rng seed: %x", seed)
rng := rand.New(rand.NewChaCha8(seed))
data := make([]float64, sampleSize*1000)
for i := range data {

8
sdk/resource/benchmark_test.go
View File

@@ -5,7 +5,7 @@ package resource_test
import (
"fmt"
"math/rand"
"math/rand/v2"
"testing"
"go.opentelemetry.io/otel/attribute"
@@ -21,18 +21,18 @@ func makeAttrs(n int) (_, _ *resource.Resource) {
for i := 0; i < n; i++ {
var k string
for {
k = fmt.Sprint("k", rand.Intn(1000000000))
k = fmt.Sprint("k", rand.IntN(1000000000))
if !used[k] {
used[k] = true
break
}
}
l1[i] = attribute.String(k, fmt.Sprint("v", rand.Intn(1000000000)))
l1[i] = attribute.String(k, fmt.Sprint("v", rand.IntN(1000000000)))
if rand.Float64() < conflict {
l2[i] = l1[i]
} else {
l2[i] = attribute.String(k, fmt.Sprint("v", rand.Intn(1000000000)))
l2[i] = attribute.String(k, fmt.Sprint("v", rand.IntN(1000000000)))
}
}
return resource.NewSchemaless(l1...), resource.NewSchemaless(l2...)

26
sdk/trace/id_generator.go
View File

@@ -5,10 +5,8 @@ package trace // import "go.opentelemetry.io/otel/sdk/trace"
import (
"context"
crand "crypto/rand"
"encoding/binary"
"math/rand"
"sync"
"math/rand/v2"
"go.opentelemetry.io/otel/trace"
)
@@ -29,20 +27,15 @@ type IDGenerator interface {
// must never be done outside of a new major release.
}
type randomIDGenerator struct {
sync.Mutex
randSource *rand.Rand
}
type randomIDGenerator struct{}
var _ IDGenerator = &randomIDGenerator{}
// NewSpanID returns a non-zero span ID from a randomly-chosen sequence.
func (gen *randomIDGenerator) NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID {
gen.Lock()
defer gen.Unlock()
sid := trace.SpanID{}
for {
_, _ = gen.randSource.Read(sid[:])
binary.NativeEndian.PutUint64(sid[:], rand.Uint64())
if sid.IsValid() {
break
}
@@ -53,18 +46,17 @@ func (gen *randomIDGenerator) NewSpanID(ctx context.Context, traceID trace.Trace
// NewIDs returns a non-zero trace ID and a non-zero span ID from a
// randomly-chosen sequence.
func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID) {
gen.Lock()
defer gen.Unlock()
tid := trace.TraceID{}
sid := trace.SpanID{}
for {
_, _ = gen.randSource.Read(tid[:])
binary.NativeEndian.PutUint64(tid[:8], rand.Uint64())
binary.NativeEndian.PutUint64(tid[8:], rand.Uint64())
if tid.IsValid() {
break
}
}
for {
_, _ = gen.randSource.Read(sid[:])
binary.NativeEndian.PutUint64(sid[:], rand.Uint64())
if sid.IsValid() {
break
}
@@ -73,9 +65,5 @@ func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.
}
func defaultIDGenerator() IDGenerator {
gen := &randomIDGenerator{}
var rngSeed int64
_ = binary.Read(crand.Reader, binary.LittleEndian, &rngSeed)
gen.randSource = rand.New(rand.NewSource(rngSeed))
return gen
return &randomIDGenerator{}
}

2
sdk/trace/provider_test.go
View File

@@ -7,7 +7,7 @@ import (
"context"
"errors"
"fmt"
"math/rand"
"math/rand/v2"
"testing"
"github.com/stretchr/testify/assert"

2
sdk/trace/sampling_test.go
View File

@@ -6,7 +6,7 @@ package trace
import (
"context"
"fmt"
"math/rand"
"math/rand/v2"
"testing"
"github.com/stretchr/testify/assert"