[GitHub] [beam] lostluck commented on a change in pull request #15206: [Beam-10166] Improve execution time errors

[GitBox <gi...@apache.org>]

lostluck commented on a change in pull request #15206:
URL: https://github.com/apache/beam/pull/15206#discussion_r675222275



##########
File path: sdks/go/pkg/beam/core/runtime/exec/util.go
##########
@@ -33,13 +34,29 @@ func (g *GenID) New() UnitID {
 	return UnitID(g.last)
 }
 
+type doFnError struct {
+	doFn string
+	err  error
+	uid  UnitID
+	pid  string
+}
+
+func (e *doFnError) Error() string {
+	return fmt.Sprintf("DoFn[<%d>;<%s>]<%s> returned error:<%s>", e.uid, e.pid, e.doFn, e.err)
+}
+
 // callNoPanic calls the given function and catches any panic.
 func callNoPanic(ctx context.Context, fn func(context.Context) error) (err error) {
 	defer func() {
 		if r := recover(); r != nil {
-			// Top level error is the panic itself, but also include the stack trace as the original error.
-			// Higher levels can then add appropriate context without getting pushed down by the stack trace.
-			err = errors.SetTopLevelMsgf(errors.Errorf("panic: %v %s", r, debug.Stack()), "panic: %v", r)
+			// check if error is of type DoFn then handle it appropriately

Review comment:
       Please change this comment to
   ```suggestion
   			// Check if the panic value is from a failed DoFn, and return it without a panic trace.
   ```
   
   A comment saying 'handle it appropriately' doesn't communicate anything to the reader. What does that mean?

##########
File path: sdks/go/pkg/beam/core/runtime/exec/util_test.go
##########
@@ -0,0 +1,71 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements.  See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exec
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/apache/beam/sdks/go/pkg/beam/util/errorx"
+)
+
+// testSimpleError tests for a simple case that
+// doesn't panic
+func testSimpleError(ctx context.Context, t *testing.T) {
+	expected := errors.New("Sample error.")
+	actual := callNoPanic(ctx, func(c context.Context) error { return errors.New("Simple error.") })
+
+	if errors.Unwrap(actual) != errors.Unwrap(expected) {
+		t.Errorf("Simple error reporting failed.")
+	}
+}
+
+// testPanicError tests for the case in which a normal
+// error is passed to panic, resulting in panic trace.
+func testPanicError(ctx context.Context, t *testing.T) {
+	actual := callNoPanic(ctx, func(c context.Context) error { panic("Panic error") })
+	if !strings.Contains(actual.Error(), "panic:") {
+		t.Errorf("Caught in panic.")
+	}
+}
+
+// testWrapPanicError tests for the case in which error
+// is passed to panic from DoFn, resulting in
+// formatted error message for DoFn.
+func testWrapPanicError(ctx context.Context, t *testing.T) {
+	parDoError := doFnError{
+		doFn: "sumFn",
+		err:  errors.New("SumFn error"),
+		uid:  1,
+		pid:  "Plan ID",
+	}
+	var err errorx.GuardedError
+	err.TrySetError(&parDoError)
+	actual := callNoPanic(ctx, func(c context.Context) error { panic(parDoError) })
+
+	if strings.Contains(actual.Error(), "panic:") {
+		t.Errorf("Error not wrapped! Caught in panic")
+	}
+}
+
+func TestCallNoPanic(t *testing.T) {

Review comment:
       Split this into the 3 separate test functions instead of doing it like this. There's no reason to make this a "single" test.
    
   In particular use an underscore to describe the cases
   
   func TestCallNoPanic_simpleError(t *testing.T) { ...}
   func TestCallNoPanic_panic(t *testing.T) { ...}
   func TestCallNoPanic_wrappedPanic(t *testing.T) { ...}
   
   Testing in Go is well described in the testing package overview.: https://pkg.go.dev/testing#pkg-overview 




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