[receiver/googlecloudpubsubreceiver] Fix memory leak during shutdown (#…

…32361)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
This PR contains the following changes:
1. Add `Close` call to the receiver's GRPC client. Without this,
goroutines were being leaked on shutdown.
2. Change `grpc.Dial` -> `grpc.NewClient`. They offer the same
functionality, but `Dial` is being deprecated in favor of `NewClient`.
3. Enable `goleak` checks on this receiver to help ensure no goroutines
are being leaked.
4. Change a couple `Assert.Nil` calls to `Assert.NoError`. The output of
`NoError` includes the error message if hit, `Nil` simply includes the
object's address, i.e. `&status.Error{s:(*status.Status)(0xc00007e158)}`

**Link to tracking Issue:** <Issue number if applicable>
#30438

**Testing:** <Describe what testing was performed and which tests were
added.>
All existing tests are passing, as well as added goleak check.

.chloggen/goleak_googlepubsubrec.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: googlecloudpubsubreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix memory leak during shutdown
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32361]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/googlecloudpubsubreceiver/metadata.yaml

@@ -18,5 +18,8 @@ tests:
   skip_lifecycle: true
   skip_shutdown: true
   goleak:
-    skip: true
+    skip: false
+    ignore:
+      # See https://github.com/census-instrumentation/opencensus-go/issues/1191 for more information.
+      top: go.opencensus.io/stats/view.(*worker).start
 

receiver/googlecloudpubsubreceiver/receiver.go

@@ -26,7 +26,9 @@ import (
 	"go.uber.org/zap"
 	"google.golang.org/api/option"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/status"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/googlecloudpubsubreceiver/internal"
 )
@@ -76,7 +78,7 @@ func (receiver *pubsubReceiver) generateClientOptions() (copts []option.ClientOp
 			if receiver.userAgent != "" {
 				dialOpts = append(dialOpts, grpc.WithUserAgent(receiver.userAgent))
 			}
-			conn, _ := grpc.Dial(receiver.config.Endpoint, append(dialOpts, grpc.WithTransportCredentials(insecure.NewCredentials()))...)
+			conn, _ := grpc.NewClient(receiver.config.Endpoint, append(dialOpts, grpc.WithTransportCredentials(insecure.NewCredentials()))...)
 			copts = append(copts, option.WithGRPCConn(conn))
 		} else {
 			copts = append(copts, option.WithEndpoint(receiver.config.Endpoint))
@@ -113,13 +115,21 @@ func (receiver *pubsubReceiver) Start(ctx context.Context, _ component.Host) err
 }
 
 func (receiver *pubsubReceiver) Shutdown(_ context.Context) error {
+	var err error
+	if receiver.client != nil {
+		// A canceled code means the client connection is already closed,
+		// Shutdown shouldn't return an error in that case.
+		if closeErr := receiver.client.Close(); status.Code(closeErr) != codes.Canceled {
+			err = closeErr
+		}
+	}
 	if receiver.handler == nil {
-		return nil
+		return err
 	}
 	receiver.logger.Info("Stopping Google Pubsub receiver")
 	receiver.handler.CancelNow()
 	receiver.logger.Info("Stopped Google Pubsub receiver")
-	return nil
+	return err
 }
 
 func (receiver *pubsubReceiver) handleLogStrings(ctx context.Context, message *pubsubpb.ReceivedMessage) error {

receiver/googlecloudpubsubreceiver/receiver_test.go

@@ -153,6 +153,6 @@ func TestReceiver(t *testing.T) {
 		return len(logSink.AllLogs()) == 1
 	}, time.Second, 10*time.Millisecond)
 
-	assert.Nil(t, receiver.Shutdown(ctx))
-	assert.Nil(t, receiver.Shutdown(ctx))
+	assert.NoError(t, receiver.Shutdown(ctx))
+	assert.NoError(t, receiver.Shutdown(ctx))
 }