[GitHub] [beam] lukecwik commented on a diff in pull request #25186: Ensure that the BeamFnLoggingClient terminates process if stream breaks

["lukecwik (via GitHub)" <gi...@apache.org>]

lukecwik commented on code in PR #25186:
URL: https://github.com/apache/beam/pull/25186#discussion_r1095077081


##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/logging/BeamFnLoggingClient.java:
##########
@@ -287,9 +284,24 @@ public void run() {
         outboundObserver.onError(
             Status.INTERNAL.withDescription(getStackTraceAsString(thrown)).asException());
         throw new IllegalStateException(thrown);
-      } else {
-        outboundObserver.onCompleted();
       }
+      if (inboundObserverCompletion.isDone()) {
+        try {
+          inboundObserverCompletion.get();
+          throw new IllegalStateException(
+              "Logging stream terminated unexpectedly with success before it was closed by the client.");
+        } catch (ExecutionException e) {
+          throw new IllegalStateException(
+              "Logging stream terminated unexpectedly before it was closed by the client with error: "
+                  + e.getCause());
+        } catch (InterruptedException e) {
+          // Should never happen because of the isDone check.
+          Thread.currentThread().interrupt();
+          throw new RuntimeException(e);
+        }
+      }
+
+      outboundObserver.onCompleted();

Review Comment:
   We can't call outboundObserver.onCompleted() if we already called outboundObserver.onError()



##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/logging/BeamFnLoggingClient.java:
##########
@@ -102,7 +104,7 @@ public BeamFnLoggingClient(
       Function<Endpoints.ApiServiceDescriptor, ManagedChannel> channelFactory) {
     this.apiServiceDescriptor = apiServiceDescriptor;
     this.inboundObserverCompletion = new CompletableFuture<>();
-    this.phaser = new Phaser(1);

Review Comment:
   makes sense



##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/logging/BeamFnLoggingClient.java:
##########
@@ -122,7 +124,9 @@ public BeamFnLoggingClient(
     logRecordHandler.setLevel(Level.ALL);
     logRecordHandler.setFormatter(DEFAULT_FORMATTER);
     logRecordHandler.executeOn(options.as(ExecutorOptions.class).getScheduledExecutorService());

Review Comment:
   we have a race here, `executeOn` will start the logging thread before `outboundObserver` has been initialized.
   



##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/logging/BeamFnLoggingClient.java:
##########
@@ -122,7 +124,9 @@ public BeamFnLoggingClient(
     logRecordHandler.setLevel(Level.ALL);
     logRecordHandler.setFormatter(DEFAULT_FORMATTER);
     logRecordHandler.executeOn(options.as(ExecutorOptions.class).getScheduledExecutorService());
-    outboundObserver = (CallStreamObserver<BeamFnApi.LogEntry.List>) stub.logging(inboundObserver);
+    outboundObserver =
+        new DirectStreamObserver<BeamFnApi.LogEntry.List>(
+            phaser, (CallStreamObserver<BeamFnApi.LogEntry.List>) stub.logging(inboundObserver));

Review Comment:
   There was no point in using the `DirectStreamObserver` since we guarantee that all writing to the stream happens from the single thread in `LogRecordHandler#run()` which will never be the inbound gRPC thread so we don't have to worry about waiting for the phaser and re-checking outbound observer readiness.



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