util/eventbus: log goroutine stacks when hung in CI

Updates #17680

Change-Id: Ie48dc2d64b7583d68578a28af52f6926f903ca4f
Signed-off-by: Brad Fitzpatrick <[email protected]>

cmd/derper/depaware.txt

@@ -139,7 +139,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/client/local+
         tailscale.com/types/views                                    from tailscale.com/ipn+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/net/netmon
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/ctxkey                                    from tailscale.com/tsweb+

cmd/k8s-operator/depaware.txt

@@ -848,7 +848,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/cmd/k8s-operator+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/cmd/k8s-operator+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+

cmd/tailscale/depaware.txt

@@ -171,7 +171,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/types/key+
         tailscale.com/types/views                                    from tailscale.com/tailcfg+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/net/netcheck+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dnscache+
         tailscale.com/util/cmpver                                    from tailscale.com/net/tshttpproxy+

cmd/tailscaled/depaware-min.txt

@@ -144,7 +144,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/ctxkey                                    from tailscale.com/client/tailscale/apitype+

cmd/tailscaled/depaware-minbox.txt

@@ -171,7 +171,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/cmpver                                    from tailscale.com/clientupdate

cmd/tailscaled/depaware.txt

@@ -416,7 +416,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/backoff                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/control/controlclient+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dns/resolver+
         tailscale.com/util/cmpver                                    from tailscale.com/net/dns+

cmd/tsidp/depaware.txt

@@ -253,7 +253,7 @@ tailscale.com/cmd/tsidp dependencies: (generated by github.com/tailscale/depawar
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+

tsnet/depaware.txt

@@ -248,7 +248,7 @@ tailscale.com/tsnet dependencies: (generated by github.com/tailscale/depaware)
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+

util/eventbus/subscribe.go

@@ -7,10 +7,12 @@ import (
 	"context"
 	"fmt"
 	"reflect"
+	"runtime"
 	"sync"
 	"time"
 
 	"tailscale.com/types/logger"
+	"tailscale.com/util/cibuild"
 )
 
 type DeliveredEvent struct {
@@ -329,6 +331,11 @@ func (s *SubscriberFunc[T]) dispatch(ctx context.Context, vals *queue[DeliveredE
 			select {
 			case <-s.slow.C:
 				s.logf("giving up on subscriber for %T after %v at close", t, time.Since(start))
+				if cibuild.On() {
+					all := make([]byte, 2<<20)
+					n := runtime.Stack(all, true)
+					s.logf("goroutine stacks:\n%s", all[:n])
+				}
 			case <-callDone:
 			}
 			return false