deepthi912 commented on code in PR #19637:
URL: https://github.com/apache/pinot/pull/19637#discussion_r4203804415
##########
pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/RealtimeSegmentDataManager.java:
##########
@@ -831,21 +831,26 @@ public void run() {
// persisted.
// Take upsert snapshot before starting consuming events
if (_partitionUpsertMetadataManager != null) {
+ // If the previous consuming segment released the semaphore to build
or download in parallel, it can still be
+ // mutable in the metadata, so this replica's snapshot covers its
rows up to where it stopped.
+ ConsumerCoordinator.UnsealedRelease unsealedRelease =
_consumerCoordinator.getUnsealedRelease();
+ String consumedUpToOffset =
+ unsealedRelease != null ?
unsealedRelease.stoppedAtOffset().toString() : _startOffset.toString();
Review Comment:
`_unsealedRelease` is only cleared by the segment that set it, in its own
`doOffload()`. So if N's build or download stalls and N+1 commits sealed (plain
`release()`, which sets nothing), N+2 still reads N's record and publishes an
offset from two segments back — which reads as "this replica is far behind"
when it isn't. That's the exact misreading this field exists to prevent.
Can we only use it when it's actually ahead of where this segment starts?
`StreamPartitionMsgOffset` is `Comparable`:
```java
String consumedUpToOffset = unsealedRelease != null
&& unsealedRelease.stoppedAtOffset().compareTo(_startOffset) > 0
? unsealedRelease.stoppedAtOffset().toString() : _startOffset.toString();
```
That also covers the race where the predecessor offloads between acquire and
snapshot, which today silently falls back to `_startOffset` and makes the value
nondeterministic.
##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/upsert/BasePartitionUpsertMetadataManager.java:
##########
@@ -97,6 +98,10 @@ public abstract class BasePartitionUpsertMetadataManager
implements PartitionUps
protected final ServerMetrics _serverMetrics;
protected final Logger _logger;
+ // Scoped to the caller so concurrent snapshot triggers cannot exchange
provenance. Preserve the existing virtual
+ // takeSnapshot()/doTakeSnapshot() hooks used by custom managers.
+ private final ThreadLocal<DocIdsSnapshot.Trigger> _snapshotTrigger = new
ThreadLocal<>();
Review Comment:
The ThreadLocal returns null without any error if `doTakeSnapshot()` ever
runs on a different thread, so the diagnostics would just quietly stop
appearing. The constraint you're working around is real (subclasses override
`doTakeSnapshot()`), but an overload keeps those working and makes the dataflow
explicit:
```java
protected void doTakeSnapshot() { doTakeSnapshot(null); }
protected void doTakeSnapshot(@Nullable DocIdsSnapshot.Trigger trigger) {
... }
```
##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/upsert/DocIdsSnapshot.java:
##########
@@ -0,0 +1,128 @@
+/**
+ * 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 org.apache.pinot.segment.local.upsert;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.zip.CRC32;
+import javax.annotation.Nullable;
+import
org.apache.pinot.segment.spi.index.mutable.ThreadSafeMutableRoaringBitmap;
+import org.apache.pinot.spi.utils.JsonUtils;
+import org.roaringbitmap.IntIterator;
+import org.roaringbitmap.buffer.ImmutableRoaringBitmap;
+import org.roaringbitmap.buffer.MutableRoaringBitmap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/// A persisted bitmap and its optional capture diagnostics, read from the
same file generation.
+/// The Roaring bytes remain a prefix readable by existing snapshot readers. A
versioned metadata trailer is published
+/// with that prefix through the existing temporary-file rename, so a
concurrent reader cannot pair different captures.
+public record DocIdsSnapshot(MutableRoaringBitmap docIds, @Nullable Metadata
metadata) {
+ private static final Logger LOGGER =
LoggerFactory.getLogger(DocIdsSnapshot.class);
+ private static final int MAGIC = 0x5044534D; // PDSM: Pinot doc ids snapshot
metadata
+ private static final int VERSION = 1;
+
+ /// The consumer startup that triggered a snapshot. consumedUpToOffset is
exclusive and per replica: the consumer's
+ /// start offset, or where the previous segment stopped if it was still
unsealed. It is not a consistency watermark.
+ public record Trigger(String consumingSegmentName, String
consumedUpToOffset) {
+ }
+
+ /// Which bitmap a snapshot file holds, so its CRC says what it covers.
+ public enum DocIdsType {
+ VALID_DOC_IDS, QUERYABLE_DOC_IDS
+ }
+
+ // Ignore unknown fields so an older server still reads diagnostics written
by a newer one.
+ @JsonIgnoreProperties(ignoreUnknown = true)
+ public record Metadata(long docIdsCrc, DocIdsType docIdsType, long
snapshotCapturedAtMs,
+ @Nullable String snapshotConsumingSegmentName,
@Nullable String snapshotConsumedUpToOffset) {
+ public Map<String, Object> toResponse(long nowMs) {
+ Map<String, Object> response = new HashMap<>();
+ response.put("docIdsCrc", docIdsCrc);
+ response.put("docIdsType", docIdsType.name());
+ response.put("snapshotCapturedAtMs", snapshotCapturedAtMs);
+ // Do not turn clock skew into an apparently fresh snapshot.
+ if (nowMs >= snapshotCapturedAtMs) {
+ response.put("snapshotAgeMs", nowMs - snapshotCapturedAtMs);
+ }
+ if (snapshotConsumingSegmentName != null && snapshotConsumedUpToOffset
!= null) {
+ response.put("snapshotConsumingSegmentName",
snapshotConsumingSegmentName);
+ response.put("snapshotConsumedUpToOffset", snapshotConsumedUpToOffset);
+ }
+ return response;
+ }
+ }
+
+ /// Capture the timestamp with the bitmap under its existing lock, then hash
the detached bitmap outside that lock.
+ public static ThreadSafeMutableRoaringBitmap.CardinalityAndBytes
capture(ThreadSafeMutableRoaringBitmap bitmap,
+ DocIdsType docIdsType, @Nullable Trigger trigger)
+ throws IOException {
+ ThreadSafeMutableRoaringBitmap.CardinalityAndBytes snapshot;
+ long capturedAtMs;
+ synchronized (bitmap) {
Review Comment:
This works only because
`ThreadSafeMutableRoaringBitmap.getBytesAndCardinality()` is `public
synchronized`, i.e. locks on `this`. If that class moves to a private lock, the
timestamp silently stops being atomic with the capture and nothing fails to
compile. Worth putting the combined accessor on
`ThreadSafeMutableRoaringBitmap` itself.
##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/upsert/DocIdsSnapshot.java:
##########
@@ -0,0 +1,128 @@
+/**
+ * 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 org.apache.pinot.segment.local.upsert;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.zip.CRC32;
+import javax.annotation.Nullable;
+import
org.apache.pinot.segment.spi.index.mutable.ThreadSafeMutableRoaringBitmap;
+import org.apache.pinot.spi.utils.JsonUtils;
+import org.roaringbitmap.IntIterator;
+import org.roaringbitmap.buffer.ImmutableRoaringBitmap;
+import org.roaringbitmap.buffer.MutableRoaringBitmap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/// A persisted bitmap and its optional capture diagnostics, read from the
same file generation.
+/// The Roaring bytes remain a prefix readable by existing snapshot readers. A
versioned metadata trailer is published
+/// with that prefix through the existing temporary-file rename, so a
concurrent reader cannot pair different captures.
+public record DocIdsSnapshot(MutableRoaringBitmap docIds, @Nullable Metadata
metadata) {
+ private static final Logger LOGGER =
LoggerFactory.getLogger(DocIdsSnapshot.class);
+ private static final int MAGIC = 0x5044534D; // PDSM: Pinot doc ids snapshot
metadata
+ private static final int VERSION = 1;
+
+ /// The consumer startup that triggered a snapshot. consumedUpToOffset is
exclusive and per replica: the consumer's
+ /// start offset, or where the previous segment stopped if it was still
unsealed. It is not a consistency watermark.
+ public record Trigger(String consumingSegmentName, String
consumedUpToOffset) {
+ }
+
+ /// Which bitmap a snapshot file holds, so its CRC says what it covers.
+ public enum DocIdsType {
+ VALID_DOC_IDS, QUERYABLE_DOC_IDS
+ }
+
+ // Ignore unknown fields so an older server still reads diagnostics written
by a newer one.
+ @JsonIgnoreProperties(ignoreUnknown = true)
+ public record Metadata(long docIdsCrc, DocIdsType docIdsType, long
snapshotCapturedAtMs,
+ @Nullable String snapshotConsumingSegmentName,
@Nullable String snapshotConsumedUpToOffset) {
+ public Map<String, Object> toResponse(long nowMs) {
+ Map<String, Object> response = new HashMap<>();
+ response.put("docIdsCrc", docIdsCrc);
+ response.put("docIdsType", docIdsType.name());
+ response.put("snapshotCapturedAtMs", snapshotCapturedAtMs);
+ // Do not turn clock skew into an apparently fresh snapshot.
+ if (nowMs >= snapshotCapturedAtMs) {
+ response.put("snapshotAgeMs", nowMs - snapshotCapturedAtMs);
+ }
+ if (snapshotConsumingSegmentName != null && snapshotConsumedUpToOffset
!= null) {
+ response.put("snapshotConsumingSegmentName",
snapshotConsumingSegmentName);
+ response.put("snapshotConsumedUpToOffset", snapshotConsumedUpToOffset);
+ }
+ return response;
+ }
+ }
+
+ /// Capture the timestamp with the bitmap under its existing lock, then hash
the detached bitmap outside that lock.
+ public static ThreadSafeMutableRoaringBitmap.CardinalityAndBytes
capture(ThreadSafeMutableRoaringBitmap bitmap,
+ DocIdsType docIdsType, @Nullable Trigger trigger)
+ throws IOException {
+ ThreadSafeMutableRoaringBitmap.CardinalityAndBytes snapshot;
+ long capturedAtMs;
+ synchronized (bitmap) {
+ snapshot = bitmap.getBytesAndCardinality();
+ capturedAtMs = System.currentTimeMillis();
+ }
+ ImmutableRoaringBitmap captured = new
ImmutableRoaringBitmap(ByteBuffer.wrap(snapshot.getBytes()));
+ CRC32 crc = new CRC32();
+ IntIterator iterator = captured.getIntIterator();
+ // Canonical ascending doc IDs, four big-endian bytes per ID: independent
of Roaring container layout.
+ while (iterator.hasNext()) {
+ int docId = iterator.next();
+ crc.update(docId >>> 24);
+ crc.update(docId >>> 16);
+ crc.update(docId >>> 8);
+ crc.update(docId);
+ }
+ Metadata metadata = new Metadata(crc.getValue(), docIdsType, capturedAtMs,
+ trigger != null ? trigger.consumingSegmentName() : null, trigger !=
null ? trigger.consumedUpToOffset() : null);
+ byte[] json =
JsonUtils.objectToString(metadata).getBytes(StandardCharsets.UTF_8);
+ byte[] bytes = ByteBuffer.allocate(snapshot.getBytes().length + 2 *
Integer.BYTES + json.length)
Review Comment:
Nit: this copies the whole serialized bitmap a second time — an extra
MB-scale array per segment per snapshot round on large partitions. Writing the
bitmap and the trailer as two writes in `persistDocIdsSnapshot` would avoid it.
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