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Source file src/encoding/json/bench_test.go

Documentation: encoding/json

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Large data benchmark.
     6  // The JSON data is a summary of agl's changes in the
     7  // go, webkit, and chromium open source projects.
     8  // We benchmark converting between the JSON form
     9  // and in-memory data structures.
    10  
    11  package json
    12  
    13  import (
    14  	"bytes"
    15  	"compress/gzip"
    16  	"fmt"
    17  	"internal/testenv"
    18  	"io/ioutil"
    19  	"os"
    20  	"reflect"
    21  	"runtime"
    22  	"strings"
    23  	"sync"
    24  	"testing"
    25  )
    26  
    27  type codeResponse struct {
    28  	Tree     *codeNode `json:"tree"`
    29  	Username string    `json:"username"`
    30  }
    31  
    32  type codeNode struct {
    33  	Name     string      `json:"name"`
    34  	Kids     []*codeNode `json:"kids"`
    35  	CLWeight float64     `json:"cl_weight"`
    36  	Touches  int         `json:"touches"`
    37  	MinT     int64       `json:"min_t"`
    38  	MaxT     int64       `json:"max_t"`
    39  	MeanT    int64       `json:"mean_t"`
    40  }
    41  
    42  var codeJSON []byte
    43  var codeStruct codeResponse
    44  
    45  func codeInit() {
    46  	f, err := os.Open("testdata/code.json.gz")
    47  	if err != nil {
    48  		panic(err)
    49  	}
    50  	defer f.Close()
    51  	gz, err := gzip.NewReader(f)
    52  	if err != nil {
    53  		panic(err)
    54  	}
    55  	data, err := ioutil.ReadAll(gz)
    56  	if err != nil {
    57  		panic(err)
    58  	}
    59  
    60  	codeJSON = data
    61  
    62  	if err := Unmarshal(codeJSON, &codeStruct); err != nil {
    63  		panic("unmarshal code.json: " + err.Error())
    64  	}
    65  
    66  	if data, err = Marshal(&codeStruct); err != nil {
    67  		panic("marshal code.json: " + err.Error())
    68  	}
    69  
    70  	if !bytes.Equal(data, codeJSON) {
    71  		println("different lengths", len(data), len(codeJSON))
    72  		for i := 0; i < len(data) && i < len(codeJSON); i++ {
    73  			if data[i] != codeJSON[i] {
    74  				println("re-marshal: changed at byte", i)
    75  				println("orig: ", string(codeJSON[i-10:i+10]))
    76  				println("new: ", string(data[i-10:i+10]))
    77  				break
    78  			}
    79  		}
    80  		panic("re-marshal code.json: different result")
    81  	}
    82  }
    83  
    84  func BenchmarkCodeEncoder(b *testing.B) {
    85  	if codeJSON == nil {
    86  		b.StopTimer()
    87  		codeInit()
    88  		b.StartTimer()
    89  	}
    90  	b.RunParallel(func(pb *testing.PB) {
    91  		enc := NewEncoder(ioutil.Discard)
    92  		for pb.Next() {
    93  			if err := enc.Encode(&codeStruct); err != nil {
    94  				b.Fatal("Encode:", err)
    95  			}
    96  		}
    97  	})
    98  	b.SetBytes(int64(len(codeJSON)))
    99  }
   100  
   101  func BenchmarkCodeMarshal(b *testing.B) {
   102  	if codeJSON == nil {
   103  		b.StopTimer()
   104  		codeInit()
   105  		b.StartTimer()
   106  	}
   107  	b.RunParallel(func(pb *testing.PB) {
   108  		for pb.Next() {
   109  			if _, err := Marshal(&codeStruct); err != nil {
   110  				b.Fatal("Marshal:", err)
   111  			}
   112  		}
   113  	})
   114  	b.SetBytes(int64(len(codeJSON)))
   115  }
   116  
   117  func benchMarshalBytes(n int) func(*testing.B) {
   118  	sample := []byte("hello world")
   119  	// Use a struct pointer, to avoid an allocation when passing it as an
   120  	// interface parameter to Marshal.
   121  	v := &struct {
   122  		Bytes []byte
   123  	}{
   124  		bytes.Repeat(sample, (n/len(sample))+1)[:n],
   125  	}
   126  	return func(b *testing.B) {
   127  		for i := 0; i < b.N; i++ {
   128  			if _, err := Marshal(v); err != nil {
   129  				b.Fatal("Marshal:", err)
   130  			}
   131  		}
   132  	}
   133  }
   134  
   135  func BenchmarkMarshalBytes(b *testing.B) {
   136  	// 32 fits within encodeState.scratch.
   137  	b.Run("32", benchMarshalBytes(32))
   138  	// 256 doesn't fit in encodeState.scratch, but is small enough to
   139  	// allocate and avoid the slower base64.NewEncoder.
   140  	b.Run("256", benchMarshalBytes(256))
   141  	// 4096 is large enough that we want to avoid allocating for it.
   142  	b.Run("4096", benchMarshalBytes(4096))
   143  }
   144  
   145  func BenchmarkCodeDecoder(b *testing.B) {
   146  	if codeJSON == nil {
   147  		b.StopTimer()
   148  		codeInit()
   149  		b.StartTimer()
   150  	}
   151  	b.RunParallel(func(pb *testing.PB) {
   152  		var buf bytes.Buffer
   153  		dec := NewDecoder(&buf)
   154  		var r codeResponse
   155  		for pb.Next() {
   156  			buf.Write(codeJSON)
   157  			// hide EOF
   158  			buf.WriteByte('\n')
   159  			buf.WriteByte('\n')
   160  			buf.WriteByte('\n')
   161  			if err := dec.Decode(&r); err != nil {
   162  				b.Fatal("Decode:", err)
   163  			}
   164  		}
   165  	})
   166  	b.SetBytes(int64(len(codeJSON)))
   167  }
   168  
   169  func BenchmarkUnicodeDecoder(b *testing.B) {
   170  	j := []byte(`"\uD83D\uDE01"`)
   171  	b.SetBytes(int64(len(j)))
   172  	r := bytes.NewReader(j)
   173  	dec := NewDecoder(r)
   174  	var out string
   175  	b.ResetTimer()
   176  	for i := 0; i < b.N; i++ {
   177  		if err := dec.Decode(&out); err != nil {
   178  			b.Fatal("Decode:", err)
   179  		}
   180  		r.Seek(0, 0)
   181  	}
   182  }
   183  
   184  func BenchmarkDecoderStream(b *testing.B) {
   185  	b.StopTimer()
   186  	var buf bytes.Buffer
   187  	dec := NewDecoder(&buf)
   188  	buf.WriteString(`"` + strings.Repeat("x", 1000000) + `"` + "\n\n\n")
   189  	var x interface{}
   190  	if err := dec.Decode(&x); err != nil {
   191  		b.Fatal("Decode:", err)
   192  	}
   193  	ones := strings.Repeat(" 1\n", 300000) + "\n\n\n"
   194  	b.StartTimer()
   195  	for i := 0; i < b.N; i++ {
   196  		if i%300000 == 0 {
   197  			buf.WriteString(ones)
   198  		}
   199  		x = nil
   200  		if err := dec.Decode(&x); err != nil || x != 1.0 {
   201  			b.Fatalf("Decode: %v after %d", err, i)
   202  		}
   203  	}
   204  }
   205  
   206  func BenchmarkCodeUnmarshal(b *testing.B) {
   207  	if codeJSON == nil {
   208  		b.StopTimer()
   209  		codeInit()
   210  		b.StartTimer()
   211  	}
   212  	b.RunParallel(func(pb *testing.PB) {
   213  		for pb.Next() {
   214  			var r codeResponse
   215  			if err := Unmarshal(codeJSON, &r); err != nil {
   216  				b.Fatal("Unmarshal:", err)
   217  			}
   218  		}
   219  	})
   220  	b.SetBytes(int64(len(codeJSON)))
   221  }
   222  
   223  func BenchmarkCodeUnmarshalReuse(b *testing.B) {
   224  	if codeJSON == nil {
   225  		b.StopTimer()
   226  		codeInit()
   227  		b.StartTimer()
   228  	}
   229  	b.RunParallel(func(pb *testing.PB) {
   230  		var r codeResponse
   231  		for pb.Next() {
   232  			if err := Unmarshal(codeJSON, &r); err != nil {
   233  				b.Fatal("Unmarshal:", err)
   234  			}
   235  		}
   236  	})
   237  	// TODO(bcmills): Is there a missing b.SetBytes here?
   238  }
   239  
   240  func BenchmarkUnmarshalString(b *testing.B) {
   241  	data := []byte(`"hello, world"`)
   242  	b.RunParallel(func(pb *testing.PB) {
   243  		var s string
   244  		for pb.Next() {
   245  			if err := Unmarshal(data, &s); err != nil {
   246  				b.Fatal("Unmarshal:", err)
   247  			}
   248  		}
   249  	})
   250  }
   251  
   252  func BenchmarkUnmarshalFloat64(b *testing.B) {
   253  	data := []byte(`3.14`)
   254  	b.RunParallel(func(pb *testing.PB) {
   255  		var f float64
   256  		for pb.Next() {
   257  			if err := Unmarshal(data, &f); err != nil {
   258  				b.Fatal("Unmarshal:", err)
   259  			}
   260  		}
   261  	})
   262  }
   263  
   264  func BenchmarkUnmarshalInt64(b *testing.B) {
   265  	data := []byte(`3`)
   266  	b.RunParallel(func(pb *testing.PB) {
   267  		var x int64
   268  		for pb.Next() {
   269  			if err := Unmarshal(data, &x); err != nil {
   270  				b.Fatal("Unmarshal:", err)
   271  			}
   272  		}
   273  	})
   274  }
   275  
   276  func BenchmarkIssue10335(b *testing.B) {
   277  	b.ReportAllocs()
   278  	j := []byte(`{"a":{ }}`)
   279  	b.RunParallel(func(pb *testing.PB) {
   280  		var s struct{}
   281  		for pb.Next() {
   282  			if err := Unmarshal(j, &s); err != nil {
   283  				b.Fatal(err)
   284  			}
   285  		}
   286  	})
   287  }
   288  
   289  func BenchmarkUnmapped(b *testing.B) {
   290  	b.ReportAllocs()
   291  	j := []byte(`{"s": "hello", "y": 2, "o": {"x": 0}, "a": [1, 99, {"x": 1}]}`)
   292  	b.RunParallel(func(pb *testing.PB) {
   293  		var s struct{}
   294  		for pb.Next() {
   295  			if err := Unmarshal(j, &s); err != nil {
   296  				b.Fatal(err)
   297  			}
   298  		}
   299  	})
   300  }
   301  
   302  func BenchmarkTypeFieldsCache(b *testing.B) {
   303  	var maxTypes int = 1e6
   304  	if testenv.Builder() != "" {
   305  		maxTypes = 1e3 // restrict cache sizes on builders
   306  	}
   307  
   308  	// Dynamically generate many new types.
   309  	types := make([]reflect.Type, maxTypes)
   310  	fs := []reflect.StructField{{
   311  		Type:  reflect.TypeOf(""),
   312  		Index: []int{0},
   313  	}}
   314  	for i := range types {
   315  		fs[0].Name = fmt.Sprintf("TypeFieldsCache%d", i)
   316  		types[i] = reflect.StructOf(fs)
   317  	}
   318  
   319  	// clearClear clears the cache. Other JSON operations, must not be running.
   320  	clearCache := func() {
   321  		fieldCache = sync.Map{}
   322  	}
   323  
   324  	// MissTypes tests the performance of repeated cache misses.
   325  	// This measures the time to rebuild a cache of size nt.
   326  	for nt := 1; nt <= maxTypes; nt *= 10 {
   327  		ts := types[:nt]
   328  		b.Run(fmt.Sprintf("MissTypes%d", nt), func(b *testing.B) {
   329  			nc := runtime.GOMAXPROCS(0)
   330  			for i := 0; i < b.N; i++ {
   331  				clearCache()
   332  				var wg sync.WaitGroup
   333  				for j := 0; j < nc; j++ {
   334  					wg.Add(1)
   335  					go func(j int) {
   336  						for _, t := range ts[(j*len(ts))/nc : ((j+1)*len(ts))/nc] {
   337  							cachedTypeFields(t)
   338  						}
   339  						wg.Done()
   340  					}(j)
   341  				}
   342  				wg.Wait()
   343  			}
   344  		})
   345  	}
   346  
   347  	// HitTypes tests the performance of repeated cache hits.
   348  	// This measures the average time of each cache lookup.
   349  	for nt := 1; nt <= maxTypes; nt *= 10 {
   350  		// Pre-warm a cache of size nt.
   351  		clearCache()
   352  		for _, t := range types[:nt] {
   353  			cachedTypeFields(t)
   354  		}
   355  		b.Run(fmt.Sprintf("HitTypes%d", nt), func(b *testing.B) {
   356  			b.RunParallel(func(pb *testing.PB) {
   357  				for pb.Next() {
   358  					cachedTypeFields(types[0])
   359  				}
   360  			})
   361  		})
   362  	}
   363  }
   364  

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