gianm closed pull request #5974: [Backport] Coordinator fix balance to try to
move max segments instead of up to max segments
URL: https://github.com/apache/incubator-druid/pull/5974
This is a PR merged from a forked repository.
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diff --git
a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorBalancer.java
b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorBalancer.java
index cc266d705df..b4f7e22411f 100644
---
a/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorBalancer.java
+++
b/server/src/main/java/io/druid/server/coordinator/helper/DruidCoordinatorBalancer.java
@@ -20,9 +20,9 @@
package io.druid.server.coordinator.helper;
import com.google.common.collect.Lists;
-import io.druid.java.util.emitter.EmittingLogger;
import io.druid.client.ImmutableDruidServer;
import io.druid.java.util.common.StringUtils;
+import io.druid.java.util.emitter.EmittingLogger;
import io.druid.server.coordinator.BalancerSegmentHolder;
import io.druid.server.coordinator.BalancerStrategy;
import io.druid.server.coordinator.CoordinatorStats;
@@ -40,6 +40,7 @@
import java.util.NavigableSet;
import java.util.SortedSet;
import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
/**
*/
@@ -103,15 +104,16 @@ private void balanceTier(
return;
}
- final List<ServerHolder> serverHolderList = Lists.newArrayList(servers);
+ final List<ServerHolder> toMoveFrom = Lists.newArrayList(servers);
+ final List<ServerHolder> toMoveTo = Lists.newArrayList(servers);
- if (serverHolderList.size() <= 1) {
+ if (toMoveTo.size() <= 1) {
log.info("[%s]: One or fewer servers found. Cannot balance.", tier);
return;
}
int numSegments = 0;
- for (ServerHolder server : serverHolderList) {
+ for (ServerHolder server : toMoveFrom) {
numSegments += server.getServer().getSegments().size();
}
@@ -119,20 +121,31 @@ private void balanceTier(
log.info("No segments found. Cannot balance.");
return;
}
+
+ final int maxToLoad =
params.getCoordinatorDynamicConfig().getMaxSegmentsInNodeLoadingQueue();
long unmoved = 0L;
- for (int iter = 0; iter < maxSegmentsToMove; iter++) {
- final BalancerSegmentHolder segmentToMove =
strategy.pickSegmentToMove(serverHolderList);
+ for (int moved = 0; (moved + unmoved) < maxSegmentsToMove;) {
+ final BalancerSegmentHolder segmentToMove =
strategy.pickSegmentToMove(toMoveFrom);
if (segmentToMove != null &&
params.getAvailableSegments().contains(segmentToMove.getSegment())) {
- final ServerHolder holder =
strategy.findNewSegmentHomeBalancer(segmentToMove.getSegment(),
serverHolderList);
+ final List<ServerHolder> toMoveToWithLoadQueueCapacity =
+ toMoveTo.stream()
+ .filter(s -> maxToLoad <= 0 ||
s.getNumberOfSegmentsInQueue() < maxToLoad)
+ .collect(Collectors.toList());
- if (holder != null) {
- moveSegment(segmentToMove, holder.getServer(), params);
+ final ServerHolder destinationHolder =
+ strategy.findNewSegmentHomeBalancer(segmentToMove.getSegment(),
toMoveToWithLoadQueueCapacity);
+
+ if (destinationHolder != null) {
+ moveSegment(segmentToMove, destinationHolder.getServer(), params);
+ moved++;
} else {
- ++unmoved;
+ log.info("Segment [%s] is 'optimally' placed.",
segmentToMove.getSegment().getIdentifier());
+ unmoved++;
}
}
}
+
if (unmoved == maxSegmentsToMove) {
// Cluster should be alive and constantly adjusting
log.info("No good moves found in tier [%s]", tier);
@@ -140,7 +153,7 @@ private void balanceTier(
stats.addToTieredStat("unmovedCount", tier, unmoved);
stats.addToTieredStat("movedCount", tier,
currentlyMovingSegments.get(tier).size());
if (params.getCoordinatorDynamicConfig().emitBalancingStats()) {
- strategy.emitStats(tier, stats, serverHolderList);
+ strategy.emitStats(tier, stats, toMoveFrom);
}
log.info(
"[%s]: Segments Moved: [%d] Segments Let Alone: [%d]",
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