github.com/FenixAra/go@v0.0.0-20170127160404-96ea0918e670/src/runtime/debug/garbage_test.go (about)

     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  	"runtime"
     9  	. "runtime/debug"
    10  	"testing"
    11  	"time"
    12  )
    13  
    14  func TestReadGCStats(t *testing.T) {
    15  	defer SetGCPercent(SetGCPercent(-1))
    16  
    17  	var stats GCStats
    18  	var mstats runtime.MemStats
    19  	var min, max time.Duration
    20  
    21  	// First ReadGCStats will allocate, second should not,
    22  	// especially if we follow up with an explicit garbage collection.
    23  	stats.PauseQuantiles = make([]time.Duration, 10)
    24  	ReadGCStats(&stats)
    25  	runtime.GC()
    26  
    27  	// Assume these will return same data: no GC during ReadGCStats.
    28  	ReadGCStats(&stats)
    29  	runtime.ReadMemStats(&mstats)
    30  
    31  	if stats.NumGC != int64(mstats.NumGC) {
    32  		t.Errorf("stats.NumGC = %d, but mstats.NumGC = %d", stats.NumGC, mstats.NumGC)
    33  	}
    34  	if stats.PauseTotal != time.Duration(mstats.PauseTotalNs) {
    35  		t.Errorf("stats.PauseTotal = %d, but mstats.PauseTotalNs = %d", stats.PauseTotal, mstats.PauseTotalNs)
    36  	}
    37  	if stats.LastGC.UnixNano() != int64(mstats.LastGC) {
    38  		t.Errorf("stats.LastGC.UnixNano = %d, but mstats.LastGC = %d", stats.LastGC.UnixNano(), mstats.LastGC)
    39  	}
    40  	n := int(mstats.NumGC)
    41  	if n > len(mstats.PauseNs) {
    42  		n = len(mstats.PauseNs)
    43  	}
    44  	if len(stats.Pause) != n {
    45  		t.Errorf("len(stats.Pause) = %d, want %d", len(stats.Pause), n)
    46  	} else {
    47  		off := (int(mstats.NumGC) + len(mstats.PauseNs) - 1) % len(mstats.PauseNs)
    48  		for i := 0; i < n; i++ {
    49  			dt := stats.Pause[i]
    50  			if dt != time.Duration(mstats.PauseNs[off]) {
    51  				t.Errorf("stats.Pause[%d] = %d, want %d", i, dt, mstats.PauseNs[off])
    52  			}
    53  			if max < dt {
    54  				max = dt
    55  			}
    56  			if min > dt || i == 0 {
    57  				min = dt
    58  			}
    59  			off = (off + len(mstats.PauseNs) - 1) % len(mstats.PauseNs)
    60  		}
    61  	}
    62  
    63  	q := stats.PauseQuantiles
    64  	nq := len(q)
    65  	if q[0] != min || q[nq-1] != max {
    66  		t.Errorf("stats.PauseQuantiles = [%d, ..., %d], want [%d, ..., %d]", q[0], q[nq-1], min, max)
    67  	}
    68  
    69  	for i := 0; i < nq-1; i++ {
    70  		if q[i] > q[i+1] {
    71  			t.Errorf("stats.PauseQuantiles[%d]=%d > stats.PauseQuantiles[%d]=%d", i, q[i], i+1, q[i+1])
    72  		}
    73  	}
    74  
    75  	// compare memory stats with gc stats:
    76  	if len(stats.PauseEnd) != n {
    77  		t.Fatalf("len(stats.PauseEnd) = %d, want %d", len(stats.PauseEnd), n)
    78  	}
    79  	off := (int(mstats.NumGC) + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
    80  	for i := 0; i < n; i++ {
    81  		dt := stats.PauseEnd[i]
    82  		if dt.UnixNano() != int64(mstats.PauseEnd[off]) {
    83  			t.Errorf("stats.PauseEnd[%d] = %d, want %d", i, dt.UnixNano(), mstats.PauseEnd[off])
    84  		}
    85  		off = (off + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
    86  	}
    87  }
    88  
    89  var big = make([]byte, 1<<20)
    90  
    91  func TestFreeOSMemory(t *testing.T) {
    92  	var ms1, ms2 runtime.MemStats
    93  
    94  	if big == nil {
    95  		t.Skip("test is not reliable when run multiple times")
    96  	}
    97  	big = nil
    98  	runtime.GC()
    99  	runtime.ReadMemStats(&ms1)
   100  	FreeOSMemory()
   101  	runtime.ReadMemStats(&ms2)
   102  	if ms1.HeapReleased >= ms2.HeapReleased {
   103  		t.Errorf("released before=%d; released after=%d; did not go up", ms1.HeapReleased, ms2.HeapReleased)
   104  	}
   105  }
   106  
   107  func TestSetGCPercent(t *testing.T) {
   108  	// Test that the variable is being set and returned correctly.
   109  	// Assume the percentage itself is implemented fine during GC,
   110  	// which is harder to test.
   111  	old := SetGCPercent(123)
   112  	new := SetGCPercent(old)
   113  	if new != 123 {
   114  		t.Errorf("SetGCPercent(123); SetGCPercent(x) = %d, want 123", new)
   115  	}
   116  }
   117  
   118  func TestSetMaxThreadsOvf(t *testing.T) {
   119  	// Verify that a big threads count will not overflow the int32
   120  	// maxmcount variable, causing a panic (see Issue 16076).
   121  	//
   122  	// This can only happen when ints are 64 bits, since on platforms
   123  	// with 32 bit ints SetMaxThreads (which takes an int parameter)
   124  	// cannot be given anything that will overflow an int32.
   125  	//
   126  	// Call SetMaxThreads with 1<<31, but only on 64 bit systems.
   127  	nt := SetMaxThreads(1 << (30 + ^uint(0)>>63))
   128  	SetMaxThreads(nt) // restore previous value
   129  }