libgo/go/runtime/gc_test.go

   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 package runtime_test
   6
   7 import (
   8         "os"
   9         "reflect"
  10         "runtime"
  11         "runtime/debug"
  12         "testing"
  13         "time"
  14         "unsafe"
  15 )
  16
  17 func TestGcSys(t *testing.T) {
  18         if os.Getenv("GOGC") == "off" {
  19                 t.Skip("skipping test; GOGC=off in environment")
  20         }
  21         got := runTestProg(t, "testprog", "GCSys")
  22         want := "OK\n"
  23         if got != want {
  24                 t.Fatalf("expected %q, but got %q", want, got)
  25         }
  26 }
  27
  28 func TestGcDeepNesting(t *testing.T) {
  29         type T [2][2][2][2][2][2][2][2][2][2]*int
  30         a := new(T)
  31
  32         // Prevent the compiler from applying escape analysis.
  33         // This makes sure new(T) is allocated on heap, not on the stack.
  34         t.Logf("%p", a)
  35
  36         a[0][0][0][0][0][0][0][0][0][0] = new(int)
  37         *a[0][0][0][0][0][0][0][0][0][0] = 13
  38         runtime.GC()
  39         if *a[0][0][0][0][0][0][0][0][0][0] != 13 {
  40                 t.Fail()
  41         }
  42 }
  43
  44 func TestGcHashmapIndirection(t *testing.T) {
  45         defer debug.SetGCPercent(debug.SetGCPercent(1))
  46         runtime.GC()
  47         type T struct {
  48                 a [256]int
  49         }
  50         m := make(map[T]T)
  51         for i := 0; i < 2000; i++ {
  52                 var a T
  53                 a.a[0] = i
  54                 m[a] = T{}
  55         }
  56 }
  57
  58 func TestGcArraySlice(t *testing.T) {
  59         type X struct {
  60                 buf     [1]byte
  61                 nextbuf []byte
  62                 next    *X
  63         }
  64         var head *X
  65         for i := 0; i < 10; i++ {
  66                 p := &X{}
  67                 p.buf[0] = 42
  68                 p.next = head
  69                 if head != nil {
  70                         p.nextbuf = head.buf[:]
  71                 }
  72                 head = p
  73                 runtime.GC()
  74         }
  75         for p := head; p != nil; p = p.next {
  76                 if p.buf[0] != 42 {
  77                         t.Fatal("corrupted heap")
  78                 }
  79         }
  80 }
  81
  82 func TestGcRescan(t *testing.T) {
  83         type X struct {
  84                 c     chan error
  85                 nextx *X
  86         }
  87         type Y struct {
  88                 X
  89                 nexty *Y
  90                 p     *int
  91         }
  92         var head *Y
  93         for i := 0; i < 10; i++ {
  94                 p := &Y{}
  95                 p.c = make(chan error)
  96                 if head != nil {
  97                         p.nextx = &head.X
  98                 }
  99                 p.nexty = head
 100                 p.p = new(int)
 101                 *p.p = 42
 102                 head = p
 103                 runtime.GC()
 104         }
 105         for p := head; p != nil; p = p.nexty {
 106                 if *p.p != 42 {
 107                         t.Fatal("corrupted heap")
 108                 }
 109         }
 110 }
 111
 112 func TestGcLastTime(t *testing.T) {
 113         ms := new(runtime.MemStats)
 114         t0 := time.Now().UnixNano()
 115         runtime.GC()
 116         t1 := time.Now().UnixNano()
 117         runtime.ReadMemStats(ms)
 118         last := int64(ms.LastGC)
 119         if t0 > last || last > t1 {
 120                 t.Fatalf("bad last GC time: got %v, want [%v, %v]", last, t0, t1)
 121         }
 122         pause := ms.PauseNs[(ms.NumGC+255)%256]
 123         // Due to timer granularity, pause can actually be 0 on windows
 124         // or on virtualized environments.
 125         if pause == 0 {
 126                 t.Logf("last GC pause was 0")
 127         } else if pause > 10e9 {
 128                 t.Logf("bad last GC pause: got %v, want [0, 10e9]", pause)
 129         }
 130 }
 131
 132 var hugeSink interface{}
 133
 134 func TestHugeGCInfo(t *testing.T) {
 135         // The test ensures that compiler can chew these huge types even on weakest machines.
 136         // The types are not allocated at runtime.
 137         if hugeSink != nil {
 138                 // 400MB on 32 bots, 4TB on 64-bits.
 139                 const n = (400 << 20) + (unsafe.Sizeof(uintptr(0))-4)<<40
 140                 hugeSink = new([n]*byte)
 141                 hugeSink = new([n]uintptr)
 142                 hugeSink = new(struct {
 143                         x float64
 144                         y [n]*byte
 145                         z []string
 146                 })
 147                 hugeSink = new(struct {
 148                         x float64
 149                         y [n]uintptr
 150                         z []string
 151                 })
 152         }
 153 }
 154
 155 /*
 156 func TestPeriodicGC(t *testing.T) {
 157         // Make sure we're not in the middle of a GC.
 158         runtime.GC()
 159
 160         var ms1, ms2 runtime.MemStats
 161         runtime.ReadMemStats(&ms1)
 162
 163         // Make periodic GC run continuously.
 164         orig := *runtime.ForceGCPeriod
 165         *runtime.ForceGCPeriod = 0
 166
 167         // Let some periodic GCs happen. In a heavily loaded system,
 168         // it's possible these will be delayed, so this is designed to
 169         // succeed quickly if things are working, but to give it some
 170         // slack if things are slow.
 171         var numGCs uint32
 172         const want = 2
 173         for i := 0; i < 20 && numGCs < want; i++ {
 174                 time.Sleep(5 * time.Millisecond)
 175
 176                 // Test that periodic GC actually happened.
 177                 runtime.ReadMemStats(&ms2)
 178                 numGCs = ms2.NumGC - ms1.NumGC
 179         }
 180         *runtime.ForceGCPeriod = orig
 181
 182         if numGCs < want {
 183                 t.Fatalf("no periodic GC: got %v GCs, want >= 2", numGCs)
 184         }
 185 }
 186 */
 187
 188 func BenchmarkSetTypePtr(b *testing.B) {
 189         benchSetType(b, new(*byte))
 190 }
 191
 192 func BenchmarkSetTypePtr8(b *testing.B) {
 193         benchSetType(b, new([8]*byte))
 194 }
 195
 196 func BenchmarkSetTypePtr16(b *testing.B) {
 197         benchSetType(b, new([16]*byte))
 198 }
 199
 200 func BenchmarkSetTypePtr32(b *testing.B) {
 201         benchSetType(b, new([32]*byte))
 202 }
 203
 204 func BenchmarkSetTypePtr64(b *testing.B) {
 205         benchSetType(b, new([64]*byte))
 206 }
 207
 208 func BenchmarkSetTypePtr126(b *testing.B) {
 209         benchSetType(b, new([126]*byte))
 210 }
 211
 212 func BenchmarkSetTypePtr128(b *testing.B) {
 213         benchSetType(b, new([128]*byte))
 214 }
 215
 216 func BenchmarkSetTypePtrSlice(b *testing.B) {
 217         benchSetType(b, make([]*byte, 1<<10))
 218 }
 219
 220 type Node1 struct {
 221         Value       [1]uintptr
 222         Left, Right *byte
 223 }
 224
 225 func BenchmarkSetTypeNode1(b *testing.B) {
 226         benchSetType(b, new(Node1))
 227 }
 228
 229 func BenchmarkSetTypeNode1Slice(b *testing.B) {
 230         benchSetType(b, make([]Node1, 32))
 231 }
 232
 233 type Node8 struct {
 234         Value       [8]uintptr
 235         Left, Right *byte
 236 }
 237
 238 func BenchmarkSetTypeNode8(b *testing.B) {
 239         benchSetType(b, new(Node8))
 240 }
 241
 242 func BenchmarkSetTypeNode8Slice(b *testing.B) {
 243         benchSetType(b, make([]Node8, 32))
 244 }
 245
 246 type Node64 struct {
 247         Value       [64]uintptr
 248         Left, Right *byte
 249 }
 250
 251 func BenchmarkSetTypeNode64(b *testing.B) {
 252         benchSetType(b, new(Node64))
 253 }
 254
 255 func BenchmarkSetTypeNode64Slice(b *testing.B) {
 256         benchSetType(b, make([]Node64, 32))
 257 }
 258
 259 type Node64Dead struct {
 260         Left, Right *byte
 261         Value       [64]uintptr
 262 }
 263
 264 func BenchmarkSetTypeNode64Dead(b *testing.B) {
 265         benchSetType(b, new(Node64Dead))
 266 }
 267
 268 func BenchmarkSetTypeNode64DeadSlice(b *testing.B) {
 269         benchSetType(b, make([]Node64Dead, 32))
 270 }
 271
 272 type Node124 struct {
 273         Value       [124]uintptr
 274         Left, Right *byte
 275 }
 276
 277 func BenchmarkSetTypeNode124(b *testing.B) {
 278         benchSetType(b, new(Node124))
 279 }
 280
 281 func BenchmarkSetTypeNode124Slice(b *testing.B) {
 282         benchSetType(b, make([]Node124, 32))
 283 }
 284
 285 type Node126 struct {
 286         Value       [126]uintptr
 287         Left, Right *byte
 288 }
 289
 290 func BenchmarkSetTypeNode126(b *testing.B) {
 291         benchSetType(b, new(Node126))
 292 }
 293
 294 func BenchmarkSetTypeNode126Slice(b *testing.B) {
 295         benchSetType(b, make([]Node126, 32))
 296 }
 297
 298 type Node128 struct {
 299         Value       [128]uintptr
 300         Left, Right *byte
 301 }
 302
 303 func BenchmarkSetTypeNode128(b *testing.B) {
 304         benchSetType(b, new(Node128))
 305 }
 306
 307 func BenchmarkSetTypeNode128Slice(b *testing.B) {
 308         benchSetType(b, make([]Node128, 32))
 309 }
 310
 311 type Node130 struct {
 312         Value       [130]uintptr
 313         Left, Right *byte
 314 }
 315
 316 func BenchmarkSetTypeNode130(b *testing.B) {
 317         benchSetType(b, new(Node130))
 318 }
 319
 320 func BenchmarkSetTypeNode130Slice(b *testing.B) {
 321         benchSetType(b, make([]Node130, 32))
 322 }
 323
 324 type Node1024 struct {
 325         Value       [1024]uintptr
 326         Left, Right *byte
 327 }
 328
 329 func BenchmarkSetTypeNode1024(b *testing.B) {
 330         benchSetType(b, new(Node1024))
 331 }
 332
 333 func BenchmarkSetTypeNode1024Slice(b *testing.B) {
 334         benchSetType(b, make([]Node1024, 32))
 335 }
 336
 337 func benchSetType(b *testing.B, x interface{}) {
 338         v := reflect.ValueOf(x)
 339         t := v.Type()
 340         switch t.Kind() {
 341         case reflect.Ptr:
 342                 b.SetBytes(int64(t.Elem().Size()))
 343         case reflect.Slice:
 344                 b.SetBytes(int64(t.Elem().Size()) * int64(v.Len()))
 345         }
 346         b.ResetTimer()
 347         //runtime.BenchSetType(b.N, x)
 348 }
 349
 350 func BenchmarkAllocation(b *testing.B) {
 351         type T struct {
 352                 x, y *byte
 353         }
 354         ngo := runtime.GOMAXPROCS(0)
 355         work := make(chan bool, b.N+ngo)
 356         result := make(chan *T)
 357         for i := 0; i < b.N; i++ {
 358                 work <- true
 359         }
 360         for i := 0; i < ngo; i++ {
 361                 work <- false
 362         }
 363         for i := 0; i < ngo; i++ {
 364                 go func() {
 365                         var x *T
 366                         for <-work {
 367                                 for i := 0; i < 1000; i++ {
 368                                         x = &T{}
 369                                 }
 370                         }
 371                         result <- x
 372                 }()
 373         }
 374         for i := 0; i < ngo; i++ {
 375                 <-result
 376         }
 377 }
 378
 379 func TestPrintGC(t *testing.T) {
 380         if testing.Short() {
 381                 t.Skip("Skipping in short mode")
 382         }
 383         defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
 384         done := make(chan bool)
 385         go func() {
 386                 for {
 387                         select {
 388                         case <-done:
 389                                 return
 390                         default:
 391                                 runtime.GC()
 392                         }
 393                 }
 394         }()
 395         for i := 0; i < 1e4; i++ {
 396                 func() {
 397                         defer print("")
 398                 }()
 399         }
 400         close(done)
 401 }
 402
 403 /*
 404
 405 // The implicit y, ok := x.(error) for the case error
 406 // in testTypeSwitch used to not initialize the result y
 407 // before passing &y to assertE2I2GC.
 408 // Catch this by making assertE2I2 call runtime.GC,
 409 // which will force a stack scan and failure if there are
 410 // bad pointers, and then fill the stack with bad pointers
 411 // and run the type switch.
 412 func TestAssertE2I2Liveness(t *testing.T) {
 413         // Note that this flag is defined in export_test.go
 414         // and is not available to ordinary imports of runtime.
 415         *runtime.TestingAssertE2I2GC = true
 416         defer func() {
 417                 *runtime.TestingAssertE2I2GC = false
 418         }()
 419
 420         poisonStack()
 421         testTypeSwitch(io.EOF)
 422         poisonStack()
 423         testAssert(io.EOF)
 424         poisonStack()
 425         testAssertVar(io.EOF)
 426 }
 427
 428 func poisonStack() uintptr {
 429         var x [1000]uintptr
 430         for i := range x {
 431                 x[i] = 0xff
 432         }
 433         return x[123]
 434 }
 435
 436 func testTypeSwitch(x interface{}) error {
 437         switch y := x.(type) {
 438         case nil:
 439                 // ok
 440         case error:
 441                 return y
 442         }
 443         return nil
 444 }
 445
 446 func testAssert(x interface{}) error {
 447         if y, ok := x.(error); ok {
 448                 return y
 449         }
 450         return nil
 451 }
 452
 453 func testAssertVar(x interface{}) error {
 454         var y, ok = x.(error)
 455         if ok {
 456                 return y
 457         }
 458         return nil
 459 }
 460
 461 func TestAssertE2T2Liveness(t *testing.T) {
 462         *runtime.TestingAssertE2T2GC = true
 463         defer func() {
 464                 *runtime.TestingAssertE2T2GC = false
 465         }()
 466
 467         poisonStack()
 468         testIfaceEqual(io.EOF)
 469 }
 470
 471 var a bool
 472
 473 //go:noinline
 474 func testIfaceEqual(x interface{}) {
 475         if x == "abc" {
 476                 a = true
 477         }
 478 }
 479
 480 func TestPageAccounting(t *testing.T) {
 481         // Grow the heap in small increments. This used to drop the
 482         // pages-in-use count below zero because of a rounding
 483         // mismatch (golang.org/issue/15022).
 484         const blockSize = 64 << 10
 485         blocks := make([]*[blockSize]byte, (64<<20)/blockSize)
 486         for i := range blocks {
 487                 blocks[i] = new([blockSize]byte)
 488         }
 489
 490         // Check that the running page count matches reality.
 491         pagesInUse, counted := runtime.CountPagesInUse()
 492         if pagesInUse != counted {
 493                 t.Fatalf("mheap_.pagesInUse is %d, but direct count is %d", pagesInUse, counted)
 494         }
 495 }
 496
 497 */