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HBASE-29006. The region assignment retry logic in unconstrained and may cause workload amplification #6983

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HBASE-29006. The region assignment retry logic in unconstrained and may cause workload amplification #6983

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22 changes: 21 additions & 1 deletion hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java
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Original file line number Diff line number Diff line change
@@ -174,6 +174,8 @@ public class AssignmentManager {

public static final int DEFAULT_FORCE_REGION_RETAINMENT_RETRIES = 600;

private static final int MAX_RETRY_LIMIT = 5;

private final ProcedureEvent<?> metaAssignEvent = new ProcedureEvent<>("meta assign");
private final ProcedureEvent<?> metaLoadEvent = new ProcedureEvent<>("meta load");

@@ -186,6 +188,8 @@ public class AssignmentManager {
private final RegionStates regionStates = new RegionStates();
private final RegionStateStore regionStateStore;

private final Map<RegionInfo, Integer> retryCountMap = new HashMap<>();

/**
* When the operator uses this configuration option, any version between the current cluster
* version and the value of "hbase.min.version.move.system.tables" does not trigger any
@@ -2483,7 +2487,21 @@ private void processAssignmentPlans(final HashMap<RegionInfo, RegionStateNode> r
acceptPlan(regions, balancer.retainAssignment(retainMap, servers));
} catch (HBaseIOException e) {
LOG.warn("unable to retain assignment", e);
addToPendingAssignment(regions, retainMap.keySet());

for(RegionInfo hri : retainMap.keySet()) {
int retryCount = retryCountMap.getOrDefault(hri,0) + 1;
retryCountMap.put(hri, retryCount);

if(retryCount > MAX_RETRY_LIMIT) {
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Better add a backoff here? If we go with this PR, the region will be in RIT state forever and only restarting master can trigger the reassign...

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Right, we can consider using backoff to solve the feedback loop as well. Simple blocking may be to harsh on the system.

// Drop the region assignment and log an error
LOG.error("Dropping region " + hri + " after exceeding retry limit " + MAX_RETRY_LIMIT);
retryCountMap.remove(hri);
}
else {
// Add back to pending assignment for retry
addToPendingAssignment(regions, Collections.singleton(hri));
}
}
}
}

@@ -2527,6 +2545,8 @@ private void acceptPlan(final HashMap<RegionInfo, RegionStateNode> regions,
}
} else {
events[evcount++] = regionNode.getProcedureEvent();
// Remove successfully assigned regions from retryCountMap
retryCountMap.remove(hri);
}
}
}