garbage_test.go

Documentation: runtime/debug

		 1  // Copyright 2013 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 debug_test
		 6  
		 7  import (
		 8  	"internal/testenv"
		 9  	"runtime"
		10  	. "runtime/debug"
		11  	"testing"
		12  	"time"
		13  )
		14  
		15  func TestReadGCStats(t *testing.T) {
		16  	defer SetGCPercent(SetGCPercent(-1))
		17  
		18  	var stats GCStats
		19  	var mstats runtime.MemStats
		20  	var min, max time.Duration
		21  
		22  	// First ReadGCStats will allocate, second should not,
		23  	// especially if we follow up with an explicit garbage collection.
		24  	stats.PauseQuantiles = make([]time.Duration, 10)
		25  	ReadGCStats(&stats)
		26  	runtime.GC()
		27  
		28  	// Assume these will return same data: no GC during ReadGCStats.
		29  	ReadGCStats(&stats)
		30  	runtime.ReadMemStats(&mstats)
		31  
		32  	if stats.NumGC != int64(mstats.NumGC) {
		33  		t.Errorf("stats.NumGC = %d, but mstats.NumGC = %d", stats.NumGC, mstats.NumGC)
		34  	}
		35  	if stats.PauseTotal != time.Duration(mstats.PauseTotalNs) {
		36  		t.Errorf("stats.PauseTotal = %d, but mstats.PauseTotalNs = %d", stats.PauseTotal, mstats.PauseTotalNs)
		37  	}
		38  	if stats.LastGC.UnixNano() != int64(mstats.LastGC) {
		39  		t.Errorf("stats.LastGC.UnixNano = %d, but mstats.LastGC = %d", stats.LastGC.UnixNano(), mstats.LastGC)
		40  	}
		41  	n := int(mstats.NumGC)
		42  	if n > len(mstats.PauseNs) {
		43  		n = len(mstats.PauseNs)
		44  	}
		45  	if len(stats.Pause) != n {
		46  		t.Errorf("len(stats.Pause) = %d, want %d", len(stats.Pause), n)
		47  	} else {
		48  		off := (int(mstats.NumGC) + len(mstats.PauseNs) - 1) % len(mstats.PauseNs)
		49  		for i := 0; i < n; i++ {
		50  			dt := stats.Pause[i]
		51  			if dt != time.Duration(mstats.PauseNs[off]) {
		52  				t.Errorf("stats.Pause[%d] = %d, want %d", i, dt, mstats.PauseNs[off])
		53  			}
		54  			if max < dt {
		55  				max = dt
		56  			}
		57  			if min > dt || i == 0 {
		58  				min = dt
		59  			}
		60  			off = (off + len(mstats.PauseNs) - 1) % len(mstats.PauseNs)
		61  		}
		62  	}
		63  
		64  	q := stats.PauseQuantiles
		65  	nq := len(q)
		66  	if q[0] != min || q[nq-1] != max {
		67  		t.Errorf("stats.PauseQuantiles = [%d, ..., %d], want [%d, ..., %d]", q[0], q[nq-1], min, max)
		68  	}
		69  
		70  	for i := 0; i < nq-1; i++ {
		71  		if q[i] > q[i+1] {
		72  			t.Errorf("stats.PauseQuantiles[%d]=%d > stats.PauseQuantiles[%d]=%d", i, q[i], i+1, q[i+1])
		73  		}
		74  	}
		75  
		76  	// compare memory stats with gc stats:
		77  	if len(stats.PauseEnd) != n {
		78  		t.Fatalf("len(stats.PauseEnd) = %d, want %d", len(stats.PauseEnd), n)
		79  	}
		80  	off := (int(mstats.NumGC) + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
		81  	for i := 0; i < n; i++ {
		82  		dt := stats.PauseEnd[i]
		83  		if dt.UnixNano() != int64(mstats.PauseEnd[off]) {
		84  			t.Errorf("stats.PauseEnd[%d] = %d, want %d", i, dt.UnixNano(), mstats.PauseEnd[off])
		85  		}
		86  		off = (off + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
		87  	}
		88  }
		89  
		90  var big = make([]byte, 1<<20)
		91  
		92  func TestFreeOSMemory(t *testing.T) {
		93  	var ms1, ms2 runtime.MemStats
		94  
		95  	if big == nil {
		96  		t.Skip("test is not reliable when run multiple times")
		97  	}
		98  	big = nil
		99  	runtime.GC()
	 100  	runtime.ReadMemStats(&ms1)
	 101  	FreeOSMemory()
	 102  	runtime.ReadMemStats(&ms2)
	 103  	if ms1.HeapReleased >= ms2.HeapReleased {
	 104  		t.Errorf("released before=%d; released after=%d; did not go up", ms1.HeapReleased, ms2.HeapReleased)
	 105  	}
	 106  }
	 107  
	 108  var (
	 109  	setGCPercentBallast interface{}
	 110  	setGCPercentSink		interface{}
	 111  )
	 112  
	 113  func TestSetGCPercent(t *testing.T) {
	 114  	testenv.SkipFlaky(t, 20076)
	 115  
	 116  	// Test that the variable is being set and returned correctly.
	 117  	old := SetGCPercent(123)
	 118  	new := SetGCPercent(old)
	 119  	if new != 123 {
	 120  		t.Errorf("SetGCPercent(123); SetGCPercent(x) = %d, want 123", new)
	 121  	}
	 122  
	 123  	// Test that the percentage is implemented correctly.
	 124  	defer func() {
	 125  		SetGCPercent(old)
	 126  		setGCPercentBallast, setGCPercentSink = nil, nil
	 127  	}()
	 128  	SetGCPercent(100)
	 129  	runtime.GC()
	 130  	// Create 100 MB of live heap as a baseline.
	 131  	const baseline = 100 << 20
	 132  	var ms runtime.MemStats
	 133  	runtime.ReadMemStats(&ms)
	 134  	setGCPercentBallast = make([]byte, baseline-ms.Alloc)
	 135  	runtime.GC()
	 136  	runtime.ReadMemStats(&ms)
	 137  	if abs64(baseline-int64(ms.Alloc)) > 10<<20 {
	 138  		t.Fatalf("failed to set up baseline live heap; got %d MB, want %d MB", ms.Alloc>>20, baseline>>20)
	 139  	}
	 140  	// NextGC should be ~200 MB.
	 141  	const thresh = 20 << 20 // TODO: Figure out why this is so noisy on some builders
	 142  	if want := int64(2 * baseline); abs64(want-int64(ms.NextGC)) > thresh {
	 143  		t.Errorf("NextGC = %d MB, want %d±%d MB", ms.NextGC>>20, want>>20, thresh>>20)
	 144  	}
	 145  	// Create some garbage, but not enough to trigger another GC.
	 146  	for i := 0; i < int(1.2*baseline); i += 1 << 10 {
	 147  		setGCPercentSink = make([]byte, 1<<10)
	 148  	}
	 149  	setGCPercentSink = nil
	 150  	// Adjust GOGC to 50. NextGC should be ~150 MB.
	 151  	SetGCPercent(50)
	 152  	runtime.ReadMemStats(&ms)
	 153  	if want := int64(1.5 * baseline); abs64(want-int64(ms.NextGC)) > thresh {
	 154  		t.Errorf("NextGC = %d MB, want %d±%d MB", ms.NextGC>>20, want>>20, thresh>>20)
	 155  	}
	 156  
	 157  	// Trigger a GC and get back to 100 MB live with GOGC=100.
	 158  	SetGCPercent(100)
	 159  	runtime.GC()
	 160  	// Raise live to 120 MB.
	 161  	setGCPercentSink = make([]byte, int(0.2*baseline))
	 162  	// Lower GOGC to 10. This must force a GC.
	 163  	runtime.ReadMemStats(&ms)
	 164  	ngc1 := ms.NumGC
	 165  	SetGCPercent(10)
	 166  	// It may require an allocation to actually force the GC.
	 167  	setGCPercentSink = make([]byte, 1<<20)
	 168  	runtime.ReadMemStats(&ms)
	 169  	ngc2 := ms.NumGC
	 170  	if ngc1 == ngc2 {
	 171  		t.Errorf("expected GC to run but it did not")
	 172  	}
	 173  }
	 174  
	 175  func abs64(a int64) int64 {
	 176  	if a < 0 {
	 177  		return -a
	 178  	}
	 179  	return a
	 180  }
	 181  
	 182  func TestSetMaxThreadsOvf(t *testing.T) {
	 183  	// Verify that a big threads count will not overflow the int32
	 184  	// maxmcount variable, causing a panic (see Issue 16076).
	 185  	//
	 186  	// This can only happen when ints are 64 bits, since on platforms
	 187  	// with 32 bit ints SetMaxThreads (which takes an int parameter)
	 188  	// cannot be given anything that will overflow an int32.
	 189  	//
	 190  	// Call SetMaxThreads with 1<<31, but only on 64 bit systems.
	 191  	nt := SetMaxThreads(1 << (30 + ^uint(0)>>63))
	 192  	SetMaxThreads(nt) // restore previous value
	 193  }
	 194
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