runtime: goroutine leak detection by using the garbage collector

src/internal/goexperiment/flags.go

@@ -120,4 +120,7 @@ type Flags struct {
 	// RandomizedHeapBase enables heap base address randomization on 64-bit
 	// platforms.
 	RandomizedHeapBase64 bool
+
+	// GoroutineLeakFinderGC enables the Deadlock GC implementation.
+	GoroutineLeakFinderGC bool
 }

src/net/http/pprof/pprof.go

@@ -351,25 +351,27 @@ func collectProfile(p *pprof.Profile) (*profile.Profile, error) {
 }
 
 var profileSupportsDelta = map[handler]bool{
-	"allocs":       true,
-	"block":        true,
-	"goroutine":    true,
-	"heap":         true,
-	"mutex":        true,
-	"threadcreate": true,
+	"allocs":        true,
+	"block":         true,
+	"goroutine":     true,
+	"goroutineleak": true,
+	"heap":          true,
+	"mutex":         true,
+	"threadcreate":  true,
 }
 
 var profileDescriptions = map[string]string{
-	"allocs":       "A sampling of all past memory allocations",
-	"block":        "Stack traces that led to blocking on synchronization primitives",
-	"cmdline":      "The command line invocation of the current program",
-	"goroutine":    "Stack traces of all current goroutines. Use debug=2 as a query parameter to export in the same format as an unrecovered panic.",
-	"heap":         "A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.",
-	"mutex":        "Stack traces of holders of contended mutexes",
-	"profile":      "CPU profile. You can specify the duration in the seconds GET parameter. After you get the profile file, use the go tool pprof command to investigate the profile.",
-	"symbol":       "Maps given program counters to function names. Counters can be specified in a GET raw query or POST body, multiple counters are separated by '+'.",
-	"threadcreate": "Stack traces that led to the creation of new OS threads",
-	"trace":        "A trace of execution of the current program. You can specify the duration in the seconds GET parameter. After you get the trace file, use the go tool trace command to investigate the trace.",
+	"allocs":        "A sampling of all past memory allocations",
+	"block":         "Stack traces that led to blocking on synchronization primitives",
+	"cmdline":       "The command line invocation of the current program",
+	"goroutine":     "Stack traces of all current goroutines. Use debug=2 as a query parameter to export in the same format as an unrecovered panic.",
+	"goroutineleak": "Stack traces of all leaked goroutines. Use debug=2 as a query parameter to export in the same format as an unrecovered panic.",
+	"heap":          "A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.",
+	"mutex":         "Stack traces of holders of contended mutexes",
+	"profile":       "CPU profile. You can specify the duration in the seconds GET parameter. After you get the profile file, use the go tool pprof command to investigate the profile.",
+	"symbol":        "Maps given program counters to function names. Counters can be specified in a GET raw query or POST body, multiple counters are separated by '+'.",
+	"threadcreate":  "Stack traces that led to the creation of new OS threads",
+	"trace":         "A trace of execution of the current program. You can specify the duration in the seconds GET parameter. After you get the trace file, use the go tool trace command to investigate the trace.",
 }
 
 type profileEntry struct {

src/runtime/chan.go

@@ -263,11 +263,11 @@ func chansend(c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool {
 	}
 	// No stack splits between assigning elem and enqueuing mysg
 	// on gp.waiting where copystack can find it.
-	mysg.elem = ep
+	mysg.elem.set(ep)
 	mysg.waitlink = nil
 	mysg.g = gp
 	mysg.isSelect = false
-	mysg.c = c
+	mysg.c.set(c)
 	gp.waiting = mysg
 	gp.param = nil
 	c.sendq.enqueue(mysg)
@@ -298,7 +298,7 @@ func chansend(c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool {
 	if mysg.releasetime > 0 {
 		blockevent(mysg.releasetime-t0, 2)
 	}
-	mysg.c = nil
+	mysg.c.set(nil)
 	releaseSudog(mysg)
 	if closed {
 		if c.closed == 0 {
@@ -336,9 +336,9 @@ func send(c *hchan, sg *sudog, ep unsafe.Pointer, unlockf func(), skip int) {
 			c.sendx = c.recvx // c.sendx = (c.sendx+1) % c.dataqsiz
 		}
 	}
-	if sg.elem != nil {
+	if sg.elem.get() != nil {
 		sendDirect(c.elemtype, sg, ep)
-		sg.elem = nil
+		sg.elem.set(nil)
 	}
 	gp := sg.g
 	unlockf()
@@ -395,7 +395,7 @@ func sendDirect(t *_type, sg *sudog, src unsafe.Pointer) {
 	// Once we read sg.elem out of sg, it will no longer
 	// be updated if the destination's stack gets copied (shrunk).
 	// So make sure that no preemption points can happen between read & use.
-	dst := sg.elem
+	dst := sg.elem.get()
 	typeBitsBulkBarrier(t, uintptr(dst), uintptr(src), t.Size_)
 	// No need for cgo write barrier checks because dst is always
 	// Go memory.
@@ -406,7 +406,7 @@ func recvDirect(t *_type, sg *sudog, dst unsafe.Pointer) {
 	// dst is on our stack or the heap, src is on another stack.
 	// The channel is locked, so src will not move during this
 	// operation.
-	src := sg.elem
+	src := sg.elem.get()
 	typeBitsBulkBarrier(t, uintptr(dst), uintptr(src), t.Size_)
 	memmove(dst, src, t.Size_)
 }
@@ -441,9 +441,9 @@ func closechan(c *hchan) {
 		if sg == nil {
 			break
 		}
-		if sg.elem != nil {
-			typedmemclr(c.elemtype, sg.elem)
-			sg.elem = nil
+		if sg.elem.get() != nil {
+			typedmemclr(c.elemtype, sg.elem.get())
+			sg.elem.set(nil)
 		}
 		if sg.releasetime != 0 {
 			sg.releasetime = cputicks()
@@ -463,7 +463,7 @@ func closechan(c *hchan) {
 		if sg == nil {
 			break
 		}
-		sg.elem = nil
+		sg.elem.set(nil)
 		if sg.releasetime != 0 {
 			sg.releasetime = cputicks()
 		}
@@ -642,13 +642,13 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool)
 	}
 	// No stack splits between assigning elem and enqueuing mysg
 	// on gp.waiting where copystack can find it.
-	mysg.elem = ep
+	mysg.elem.set(ep)
 	mysg.waitlink = nil
 	gp.waiting = mysg
 
 	mysg.g = gp
 	mysg.isSelect = false
-	mysg.c = c
+	mysg.c.set(c)
 	gp.param = nil
 	c.recvq.enqueue(mysg)
 	if c.timer != nil {
@@ -680,7 +680,7 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool)
 	}
 	success := mysg.success
 	gp.param = nil
-	mysg.c = nil
+	mysg.c.set(nil)
 	releaseSudog(mysg)
 	return true, success
 }
@@ -727,14 +727,14 @@ func recv(c *hchan, sg *sudog, ep unsafe.Pointer, unlockf func(), skip int) {
 			typedmemmove(c.elemtype, ep, qp)
 		}
 		// copy data from sender to queue
-		typedmemmove(c.elemtype, qp, sg.elem)
+		typedmemmove(c.elemtype, qp, sg.elem.get())
 		c.recvx++
 		if c.recvx == c.dataqsiz {
 			c.recvx = 0
 		}
 		c.sendx = c.recvx // c.sendx = (c.sendx+1) % c.dataqsiz
 	}
-	sg.elem = nil
+	sg.elem.set(nil)
 	gp := sg.g
 	unlockf()
 	gp.param = unsafe.Pointer(sg)

src/runtime/crash_test.go

@@ -186,6 +186,23 @@ func buildTestProg(t *testing.T, binary string, flags ...string) (string, error)
 		t.Logf("running %v", cmd)
 		cmd.Dir = "testdata/" + binary
 		cmd = testenv.CleanCmdEnv(cmd)
+
+		// Add the goroutineleakfindergc GOEXPERIMENT unconditionally since some tests depend on it.
+		// TODO(61405): Remove this once it's enabled by default.
+		//
+		// FIXME: Remove this once profiling is enabled and goroutineleakfindergc experiment is phased out.
+		edited := false
+		for i := range cmd.Env {
+			e := cmd.Env[i]
+			if _, vars, ok := strings.Cut(e, "GOEXPERIMENT="); ok {
+				cmd.Env[i] = "GOEXPERIMENT=" + vars + ",goroutineleakfindergc"
+				edited = true
+			}
+		}
+		if !edited {
+			cmd.Env = append(cmd.Env, "GOEXPERIMENT=goroutineleakfindergc")
+		}
+
 		out, err := cmd.CombinedOutput()
 		if err != nil {
 			target.err = fmt.Errorf("building %s %v: %v\n%s", binary, flags, err, out)

src/runtime/export_test.go

@@ -1221,7 +1221,7 @@ func (t *SemTable) Enqueue(addr *uint32) {
 	s.releasetime = 0
 	s.acquiretime = 0
 	s.ticket = 0
-	t.semTable.rootFor(addr).queue(addr, s, false)
+	t.semTable.rootFor(addr).queue(addr, s, false, false)
 }
 
 // Dequeue simulates dequeuing a waiter for a semaphore (or lock) at addr.