[GitHub] [beam] lostluck commented on a diff in pull request #22225: Collect heap profile on OOM on Dataflow

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

lostluck commented on code in PR #22225:
URL: https://github.com/apache/beam/pull/22225#discussion_r920297832


##########
sdks/go/pkg/beam/util/diagnostics/diagnostics.go:
##########
@@ -0,0 +1,131 @@
+// 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 diagnostics

Review Comment:
   Please add a Package comment
   
   // Package diagnostics is a beam internal package that contains...
   // This package is not intended for end user use and can change at any time.
   
   Needs to have a blank line between it and the licence and no blank line between it and the `package diagnostics` line.



##########
sdks/go/pkg/beam/util/diagnostics/diagnostics.go:
##########
@@ -0,0 +1,131 @@
+// 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 diagnostics
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/io/filesystem"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
+)
+
+const (
+	hProfLoc     = "/tmp/hProf"
+	tempHProfLoc = "/tmp/hProf.tmp"
+)
+
+// SampleForHeapProfile checks every second if it should take a heap profile, and if so
+// it takes one and saves it to hProfLoc. A profile will be taken if either:
+// (1) the amount of memory allocated has increased since the last heap profile was taken or
+// (2) it has been 60 seconds since the last heap profile was taken
+func SampleForHeapProfile(ctx context.Context) {
+	var maxAllocatedSoFar uint64
+	maxAllocatedSoFar = 0

Review Comment:
   Please remove this line.
   
   All newly declared Go variables are zeroed by default.  
   
   While simply the declaration is preferred, `maxAllocatedSoFar := uint64(0)` is also acceptable.



##########
sdks/go/pkg/beam/util/diagnostics/diagnostics.go:
##########
@@ -0,0 +1,131 @@
+// 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 diagnostics
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/io/filesystem"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
+)
+
+const (
+	hProfLoc     = "/tmp/hProf"
+	tempHProfLoc = "/tmp/hProf.tmp"
+)
+
+// SampleForHeapProfile checks every second if it should take a heap profile, and if so
+// it takes one and saves it to hProfLoc. A profile will be taken if either:
+// (1) the amount of memory allocated has increased since the last heap profile was taken or
+// (2) it has been 60 seconds since the last heap profile was taken
+func SampleForHeapProfile(ctx context.Context) {
+	var maxAllocatedSoFar uint64
+	maxAllocatedSoFar = 0
+	samplesSkipped := 0
+	for {
+		var m runtime.MemStats
+		runtime.ReadMemStats(&m)
+		if m.Alloc > maxAllocatedSoFar || samplesSkipped >= 60 {
+			samplesSkipped = 0
+			maxAllocatedSoFar = m.Alloc
+			err := saveHeapProfile()
+			log.Warnf(ctx, "err - %v", err)
+		} else {
+			samplesSkipped++
+		}
+		// TODO(Issue #21797) - make this value and the samplesSkipped value configurable.
+		time.Sleep(1 * time.Second)
+	}
+}
+
+func saveHeapProfile() error {
+	// Write to a .tmp file before moving to final location to ensure
+	// that OOM doesn't disrupt this flow.
+	// Try removing temp file in case we ran into an error previously
+	if err := os.Remove(tempHProfLoc); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	fd, err := os.Create(tempHProfLoc)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+	buf := bufio.NewWriterSize(fd, 1<<20) // use 1MB buffer
+
+	err = pprof.WriteHeapProfile(buf)
+	if err != nil {
+		return err
+	}
+
+	if err := buf.Flush(); err != nil {
+		return err
+	}
+
+	if err := os.Remove(hProfLoc); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+
+	return os.Rename(tempHProfLoc, hProfLoc)
+}
+
+// UploadHeapPrilfe checks if a heap profile is available and uploads it to dest
+// if one is. It will first check hProfLoc for the heap profile and then it will
+// check tempHProfLoc if no file exists at hProfLoc.
+// To use, download the file and run: `go too-http=:8082 path/to/profile`

Review Comment:
   Typo and wordsmithing.
   
   ```suggestion
   // UploadHeapProfile checks if a heap profile is available and, if so, uploads it to dest.
   // It will first check hProfLoc for the heap profile and then it will
   // check tempHProfLoc if no file exists at hProfLoc.
   //
   // To examine, download the file and run: `go tool pprof -http=:8082 path/to/profile`
   ```



##########
sdks/go/pkg/beam/util/diagnostics/diagnostics.go:
##########
@@ -0,0 +1,131 @@
+// 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 diagnostics
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/io/filesystem"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
+)
+
+const (
+	hProfLoc     = "/tmp/hProf"
+	tempHProfLoc = "/tmp/hProf.tmp"
+)
+
+// SampleForHeapProfile checks every second if it should take a heap profile, and if so
+// it takes one and saves it to hProfLoc. A profile will be taken if either:
+// (1) the amount of memory allocated has increased since the last heap profile was taken or
+// (2) it has been 60 seconds since the last heap profile was taken
+func SampleForHeapProfile(ctx context.Context) {
+	var maxAllocatedSoFar uint64
+	maxAllocatedSoFar = 0
+	samplesSkipped := 0
+	for {
+		var m runtime.MemStats
+		runtime.ReadMemStats(&m)
+		if m.Alloc > maxAllocatedSoFar || samplesSkipped >= 60 {
+			samplesSkipped = 0
+			maxAllocatedSoFar = m.Alloc
+			err := saveHeapProfile()
+			log.Warnf(ctx, "err - %v", err)

Review Comment:
   This will log a warning every time, with very little context. Please make the log conditional on whether the error is `nil` or not, and add context like "failed to save heap profile: %v"



##########
sdks/go/pkg/beam/util/diagnostics/diagnostics.go:
##########
@@ -0,0 +1,131 @@
+// 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 diagnostics
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/io/filesystem"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/log"
+)
+
+const (
+	hProfLoc     = "/tmp/hProf"
+	tempHProfLoc = "/tmp/hProf.tmp"
+)
+
+// SampleForHeapProfile checks every second if it should take a heap profile, and if so
+// it takes one and saves it to hProfLoc. A profile will be taken if either:
+// (1) the amount of memory allocated has increased since the last heap profile was taken or
+// (2) it has been 60 seconds since the last heap profile was taken
+func SampleForHeapProfile(ctx context.Context) {
+	var maxAllocatedSoFar uint64
+	maxAllocatedSoFar = 0
+	samplesSkipped := 0
+	for {
+		var m runtime.MemStats
+		runtime.ReadMemStats(&m)
+		if m.Alloc > maxAllocatedSoFar || samplesSkipped >= 60 {
+			samplesSkipped = 0
+			maxAllocatedSoFar = m.Alloc
+			err := saveHeapProfile()
+			log.Warnf(ctx, "err - %v", err)
+		} else {
+			samplesSkipped++
+		}
+		// TODO(Issue #21797) - make this value and the samplesSkipped value configurable.
+		time.Sleep(1 * time.Second)
+	}
+}
+
+func saveHeapProfile() error {
+	// Write to a .tmp file before moving to final location to ensure
+	// that OOM doesn't disrupt this flow.
+	// Try removing temp file in case we ran into an error previously
+	if err := os.Remove(tempHProfLoc); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	fd, err := os.Create(tempHProfLoc)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+	buf := bufio.NewWriterSize(fd, 1<<20) // use 1MB buffer
+
+	err = pprof.WriteHeapProfile(buf)
+	if err != nil {
+		return err
+	}

Review Comment:
   To make it consistent with the other ifs.
   ```suggestion
   	if err := pprof.WriteHeapProfile(buf); err != nil {
   		return err
   	}
   ```



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