runtime,net/http/pprof: goroutine leak detection by using the garbage collector

Proposal #74609

Change-Id: I97a754b128aac1bc5b7b9ab607fcd5bb390058c8
GitHub-Last-Rev: 60f2a19
GitHub-Pull-Request: #74622
Reviewed-on: https://go-review.googlesource.com/c/go/+/688335
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: t hepudds <[email protected]>
Auto-Submit: Michael Knyszek <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>

Author: VladSaiocUber

src/cmd/link/internal/loader/loader.go

@@ -2450,6 +2450,9 @@ var blockedLinknames = map[string][]string{
 	"sync_test.runtime_blockUntilEmptyCleanupQueue":  {"sync_test"},
 	"time.runtimeIsBubbled":                          {"time"},
 	"unique.runtime_blockUntilEmptyCleanupQueue":     {"unique"},
+	// Experimental features
+	"runtime.goroutineLeakGC":    {"runtime/pprof"},
+	"runtime.goroutineleakcount": {"runtime/pprof"},
 	// Others
 	"net.newWindowsFile":                   {"net"},              // pushed from os
 	"testing/synctest.testingSynctestTest": {"testing/synctest"}, // pushed from testing

src/internal/goexperiment/exp_goroutineleakprofile_off.go

@@ -118,4 +118,7 @@ type Flags struct {
 
 	// SizeSpecializedMalloc enables malloc implementations that are specialized per size class.
 	SizeSpecializedMalloc bool
+
+	// GoroutineLeakProfile enables the collection of goroutine leak profiles.
+	GoroutineLeakProfile bool
 }

src/internal/goexperiment/exp_goroutineleakprofile_on.go

@@ -77,6 +77,7 @@ import (
 	"fmt"
 	"html"
 	"internal/godebug"
+	"internal/goexperiment"
 	"internal/profile"
 	"io"
 	"log"
@@ -353,6 +354,7 @@ func collectProfile(p *pprof.Profile) (*profile.Profile, error) {
 var profileSupportsDelta = map[handler]bool{
 	"allocs":       true,
 	"block":        true,
+	"goroutineleak":        true,
 	"goroutine":    true,
 	"heap":         true,
 	"mutex":        true,
@@ -372,6 +374,12 @@ var profileDescriptions = map[string]string{
 	"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.",
 }
 
+func init() {
+	if goexperiment.GoroutineLeakProfile {
+		profileDescriptions["goroutineleak"] = "Stack traces of all leaked goroutines. Use debug=2 as a query parameter to export in the same format as an unrecovered panic."
+	}
+}
+
 type profileEntry struct {
 	Name  string
 	Href  string

src/internal/goexperiment/flags.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/net/http/pprof/pprof.go

@@ -186,6 +186,22 @@ func buildTestProg(t *testing.T, binary string, flags ...string) (string, error)
 		t.Logf("running %v", cmd)
 		cmd.Dir = "testdata/" + binary
 		cmd = testenv.CleanCmdEnv(cmd)
+
+		// If tests need any experimental flags, add them here.
+		//
+		// TODO(vsaioc): Remove `goroutineleakprofile` once the feature is no longer experimental.
+		edited := false
+		for i := range cmd.Env {
+			e := cmd.Env[i]
+			if _, vars, ok := strings.Cut(e, "GOEXPERIMENT="); ok {
+				cmd.Env[i] = "GOEXPERIMENT=" + vars + ",goroutineleakprofile"
+				edited, _ = true, vars
+			}
+		}
+		if !edited {
+			cmd.Env = append(cmd.Env, "GOEXPERIMENT=goroutineleakprofile")
+		}
+
 		out, err := cmd.CombinedOutput()
 		if err != nil {
 			target.err = fmt.Errorf("building %s %v: %v\n%s", binary, flags, err, out)