Adding leak test framework (#2254)

leak-detect_test.go

@@ -0,0 +1,154 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package leaktest provides tools to detect leaked goroutines in tests.
+// To use it, call "defer leaktest.AfterTest(t)()" at the beginning of each
+// test that may use goroutines.
+package main
+
+import (
+	"runtime"
+	"sort"
+	"strings"
+	"time"
+)
+
+const (
+	// deadline (in seconds) upto which the go routine leak detection has to be retried.
+	leakDetectDeadline = 5
+	// pause time (in milliseconds) between each snapshot at the end of the go routine leak detection.
+	leakDetectPauseTimeMs = 50
+)
+
+// LeakDetect - type with  methods for go routine leak detection.
+type LeakDetect struct {
+	relevantRoutines map[string]bool
+}
+
+// NewLeakDetect - Initialize a LeakDetector with the snapshot of relevant Go routines.
+func NewLeakDetect() LeakDetect {
+	snapshot := LeakDetect{
+		relevantRoutines: make(map[string]bool),
+	}
+	for _, g := range pickRelevantGoroutines() {
+		snapshot.relevantRoutines[g] = true
+	}
+	return snapshot
+}
+
+// CompareCurrentSnapshot - Comapres the initial relevant stack trace with the current one (during the time of invocation).
+func (initialSnapShot LeakDetect) CompareCurrentSnapshot() []string {
+	var stackDiff []string
+	for _, g := range pickRelevantGoroutines() {
+		// Identify the Go routines those were not present in the initial snapshot.
+		// In other words a stack diff.
+		if !initialSnapShot.relevantRoutines[g] {
+			stackDiff = append(stackDiff, g)
+		}
+	}
+	return stackDiff
+}
+
+// DetectLeak - Creates a snapshot of runtiem stack and compares it with  the initial stack snapshot.
+func (initialSnapShot LeakDetect) DetectLeak(t TestErrHandler) {
+	if t.Failed() {
+		return
+	}
+	// Loop, waiting for goroutines to shut down.
+	// Wait up to 5 seconds, but finish as quickly as possible.
+	deadline := time.Now().Add(leakDetectDeadline * time.Second)
+	for {
+		// get sack snapshot of relevant go routines.
+		leaked := initialSnapShot.CompareCurrentSnapshot()
+		// current stack snapshot matches the initial one, no leaks, return.
+		if len(leaked) == 0 {
+			return
+		}
+		// wait a test again will deadline.
+		if time.Now().Before(deadline) {
+			time.Sleep(leakDetectPauseTimeMs * time.Millisecond)
+			continue
+		}
+		// after the deadline time report all the difference in the latest snapshot compared with the initial one.
+		for _, g := range leaked {
+			t.Errorf("Leaked goroutine: %v", g)
+		}
+		return
+	}
+}
+
+// DetectTestLeak -  snapshots the currently-running goroutines and returns a
+// function to be run at the end of tests to see whether any
+// goroutines leaked.
+// Usage: `defer DetectTestLeak(t)()` in beginning line of benchmarks or unit tests.
+func DetectTestLeak(t TestErrHandler) func() {
+	initialStackSnapShot := NewLeakDetect()
+	return func() {
+		initialStackSnapShot.DetectLeak(t)
+	}
+}
+
+// list of functions to be ignored from the stack trace.
+// Leak detection is done when tests are run, should ignore the tests related functions,
+// and other runtime functions while identifying leaks.
+var ignoredStackFns = []string{
+	"",
+	// Below are the stacks ignored by the upstream leaktest code.
+	"testing.Main(",
+	"testing.tRunner(",
+	"testing.tRunner(",
+	"runtime.goexit",
+	"created by runtime.gc",
+	// ignore the snapshot function.
+	// since the snapshot is taken here the entry will have the current function too.
+	"pickRelevantGoroutines",
+	"runtime.MHeap_Scavenger",
+	"signal.signal_recv",
+	"sigterm.handler",
+	"runtime_mcall",
+	"goroutine in C code",
+}
+
+// Identify whether the stack trace entry is part of ignoredStackFn .
+func isIgnoredStackFn(stack string) (ok bool) {
+	ok = true
+	for _, stackFn := range ignoredStackFns {
+		if !strings.Contains(stack, stackFn) {
+			ok = false
+			continue
+		}
+		break
+	}
+	return ok
+}
+
+// pickRelevantGoroutines returns all goroutines we care about for the purpose
+// of leak checking. It excludes testing or runtime ones.
+func pickRelevantGoroutines() (gs []string) {
+	// make a large buffer to hold the runtime stack info.
+	buf := make([]byte, 2<<20)
+	buf = buf[:runtime.Stack(buf, true)]
+	// runtime stack of go routines will be listed with 2 blank spaces between each of them, so split on "\n\n" .
+	for _, g := range strings.Split(string(buf), "\n\n") {
+		// Again split on a new line, the first line of the second half contaisn the info about the go routine.
+		sl := strings.SplitN(g, "\n", 2)
+		if len(sl) != 2 {
+			continue
+		}
+		stack := strings.TrimSpace(sl[1])
+		// ignore the testing go routine.
+		// since the tests will be invoking the leaktest it would contain the test go routine.
+		if strings.HasPrefix(stack, "testing.RunTests") {
+			continue
+		}
+		// Ignore the following go routines.
+		// testing and run time go routines should be ignored, only the application generated go routines should be taken into account.
+		if isIgnoredStackFn(stack) {
+			continue
+		}
+		gs = append(gs, g)
+	}
+	sort.Strings(gs)
+	return
+}

test-utils_test.go

@@ -46,9 +46,9 @@ func init() {
 	initNSLock()
 }
 
-// The Argument to TestServer should satidy the interface.
+// TestErrHandler - Golang Testing.T and Testing.B, and gocheck.C satisfy this interface.
-// Golang Testing.T and Testing.B, and gocheck.C satisfy the interface.
 // This makes it easy to run the TestServer from any of the tests.
+// Using this interface, functionalities to be used in tests can be made generalized, and can be integrated in benchmarks/unit tests/go check suite tests.
 type TestErrHandler interface {
 	Error(args ...interface{})
 	Errorf(format string, args ...interface{})