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Posted to commits@pinot.apache.org by ja...@apache.org on 2019/06/19 03:56:07 UTC
[incubator-pinot] 01/01: Within a partition,
only allow querying the first CONSUMING segment for the real-time
table routing
This is an automated email from the ASF dual-hosted git repository.
jackie pushed a commit to branch llc_routing_hotfix
in repository https://gitbox.apache.org/repos/asf/incubator-pinot.git
commit 77954eccad9e4e5086c7edaa41235ef823a91d1a
Author: Jackie (Xiaotian) Jiang <xa...@linkedin.com>
AuthorDate: Tue Jun 18 18:34:55 2019 -0700
Within a partition, only allow querying the first CONSUMING segment for the real-time table routing
Within a partition, we only allow querying the first CONSUMING segment (segment with instances in CONSUMING
state) for the following reasons:
- If within a partition, there are multiple CONSUMING segments (typically caused by the delay of CONSUMING to
ONLINE state transition), we can only query the first CONSUMING segment because it might contain records that
overlapped with the records in the next segment (over-consumed).
- If the instance states for a segment is partial ONLINE and partial CONSUMING (some instances finished the
CONSUMING to ONLINE state transition, others didn't), we count the segment as CONSUMING segment (most likely
the first CONSUMING segment because it is already committed and is performing the CONSUMING to ONLINE state
transition). If we don't count the segment as CONSUMING segment, then this segment is not allowed to be in the
CONSUMING state for routing purpose, and we will route all queries to the ONLINE instances which can
potentially overwhelm instance.
- It is possible that the latest CONSUMING segment is not allowed for routing purpose and we won't query it, but
it should only last for a short period of time. Once the older CONSUMING segment becomes ONLINE (all instances
finished the CONSUMING to ONLINE state transition), the latest CONSUMING segment will become the first
CONSUMING segment and will be allowed for routing purpose.
---
.../LowLevelConsumerRoutingTableBuilder.java | 6 +-
.../builder/LowLevelRoutingTableBuilderUtil.java | 76 ++++++++++------------
2 files changed, 36 insertions(+), 46 deletions(-)
diff --git a/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelConsumerRoutingTableBuilder.java b/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelConsumerRoutingTableBuilder.java
index f6c40b2..4a39da2 100644
--- a/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelConsumerRoutingTableBuilder.java
+++ b/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelConsumerRoutingTableBuilder.java
@@ -122,9 +122,9 @@ public class LowLevelConsumerRoutingTableBuilder extends GeneratorBasedRoutingTa
continue;
}
- // Replicas in CONSUMING state are only allowed on the last segment
- if (state.equalsIgnoreCase(CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel.CONSUMING)
- && segmentName.equals(validConsumingSegment)) {
+ // If the server is in CONSUMING status, the segment has to be match with the valid consuming segment
+ if (state.equals(CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel.CONSUMING)
+ && validConsumingSegment != null && segmentNameStr.equals(validConsumingSegment.getSegmentName())) {
validServers.add(instance);
}
}
diff --git a/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelRoutingTableBuilderUtil.java b/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelRoutingTableBuilderUtil.java
index 8490397..3ccf841 100644
--- a/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelRoutingTableBuilderUtil.java
+++ b/pinot-broker/src/main/java/org/apache/pinot/broker/routing/builder/LowLevelRoutingTableBuilderUtil.java
@@ -22,7 +22,7 @@ import java.util.HashMap;
import java.util.Map;
import java.util.SortedSet;
import org.apache.helix.model.ExternalView;
-import org.apache.pinot.common.utils.CommonConstants;
+import org.apache.pinot.common.utils.CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel;
import org.apache.pinot.common.utils.SegmentName;
@@ -32,7 +32,30 @@ import org.apache.pinot.common.utils.SegmentName;
public class LowLevelRoutingTableBuilderUtil {
/**
- * Compute the map of allowed 'consuming' segments for each partition.
+ * Compute the map of allowed CONSUMING segments for each partition for routing purpose.
+ * <p>Within a partition, we only allow querying the first CONSUMING segment (segment with instances in CONSUMING
+ * state) for the following reasons:
+ * <ul>
+ * <li>
+ * If within a partition, there are multiple CONSUMING segments (typically caused by the delay of CONSUMING to
+ * ONLINE state transition), we can only query the first CONSUMING segment because it might contain records that
+ * overlapped with the records in the next segment (over-consumed).
+ * </li>
+ * <li>
+ * If the instance states for a segment is partial ONLINE and partial CONSUMING (some instances finished the
+ * CONSUMING to ONLINE state transition, others didn't), we count the segment as CONSUMING segment (most likely
+ * the first CONSUMING segment because it is already committed and is performing the CONSUMING to ONLINE state
+ * transition). If we don't count the segment as CONSUMING segment, then this segment is not allowed to be in the
+ * CONSUMING state for routing purpose, and we will route all queries to the ONLINE instances which can
+ * potentially overwhelm instance.
+ * </li>
+ * <li>
+ * It is possible that the latest CONSUMING segment is not allowed for routing purpose and we won't query it, but
+ * it should only last for a short period of time. Once the older CONSUMING segment becomes ONLINE (all instances
+ * finished the CONSUMING to ONLINE state transition), the latest CONSUMING segment will become the first
+ * CONSUMING segment and will be allowed for routing purpose.
+ * </li>
+ * </ul>
*
* @param externalView helix external view
* @param sortedSegmentsByPartition map of partition to sorted set of segment names.
@@ -40,51 +63,18 @@ public class LowLevelRoutingTableBuilderUtil {
*/
public static Map<String, SegmentName> getAllowedConsumingStateSegments(ExternalView externalView,
Map<String, SortedSet<SegmentName>> sortedSegmentsByPartition) {
- Map<String, SegmentName> allowedSegmentInConsumingStateByPartition = new HashMap<>();
- for (String partition : sortedSegmentsByPartition.keySet()) {
- SortedSet<SegmentName> sortedSegmentsForPartition = sortedSegmentsByPartition.get(partition);
- SegmentName lastAllowedSegmentInConsumingState = null;
-
+ Map<String, SegmentName> allowedConsumingSegments = new HashMap<>();
+ for (Map.Entry<String, SortedSet<SegmentName>> entry : sortedSegmentsByPartition.entrySet()) {
+ String partitionId = entry.getKey();
+ SortedSet<SegmentName> sortedSegmentsForPartition = entry.getValue();
for (SegmentName segmentName : sortedSegmentsForPartition) {
- Map<String, String> helixPartitionState = externalView.getStateMap(segmentName.getSegmentName());
- boolean allInConsumingState = true;
- int replicasInConsumingState = 0;
-
- // Only keep the segment if all replicas have it in CONSUMING state
- for (String externalViewState : helixPartitionState.values()) {
- // Ignore ERROR state
- if (externalViewState
- .equalsIgnoreCase(CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel.ERROR)) {
- continue;
- }
-
- // Not all segments are in CONSUMING state, therefore don't consider the last segment assignable to CONSUMING
- // replicas
- if (externalViewState
- .equalsIgnoreCase(CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel.ONLINE)) {
- allInConsumingState = false;
- break;
- }
-
- // Otherwise count the replica as being in CONSUMING state
- if (externalViewState
- .equalsIgnoreCase(CommonConstants.Helix.StateModel.RealtimeSegmentOnlineOfflineStateModel.CONSUMING)) {
- replicasInConsumingState++;
- }
- }
-
- // If all replicas have this segment in consuming state (and not all of them are in ERROR state), then pick this
- // segment to be the last allowed segment to be in CONSUMING state
- if (allInConsumingState && 0 < replicasInConsumingState) {
- lastAllowedSegmentInConsumingState = segmentName;
+ if (externalView.getStateMap(segmentName.getSegmentName())
+ .containsValue(RealtimeSegmentOnlineOfflineStateModel.CONSUMING)) {
+ allowedConsumingSegments.put(partitionId, segmentName);
break;
}
}
-
- if (lastAllowedSegmentInConsumingState != null) {
- allowedSegmentInConsumingStateByPartition.put(partition, lastAllowedSegmentInConsumingState);
- }
}
- return allowedSegmentInConsumingStateByPartition;
+ return allowedConsumingSegments;
}
}
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