somandal commented on code in PR #15618:
URL: https://github.com/apache/pinot/pull/15618#discussion_r2076151354
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/rebalance/TableRebalancer.java:
##########
@@ -1352,26 +1380,55 @@ static boolean isExternalViewConverged(String
tableNameWithType,
Map<String, Map<String, String>> externalViewSegmentStates,
Map<String, Map<String, String>> idealStateSegmentStates, boolean
lowDiskMode, boolean bestEfforts,
@Nullable Set<String> segmentsToMonitor) {
- return isExternalViewConverged(tableNameWithType,
externalViewSegmentStates, idealStateSegmentStates, lowDiskMode,
- bestEfforts, segmentsToMonitor, LOGGER);
+ return getNumRemainingSegmentsToProcess(tableNameWithType,
externalViewSegmentStates, idealStateSegmentStates,
+ lowDiskMode, bestEfforts, segmentsToMonitor, LOGGER, true) == 0;
}
/**
- * NOTE:
- * Only check the segments in the IdealState and being monitored. Extra
segments in ExternalView are ignored because
- * they are not managed by the rebalancer.
- * For each segment checked:
- * - In regular mode, it is okay to have extra instances in ExternalView as
long as the instance states in IdealState
- * are reached.
- * - In low disk mode, instance states in ExternalView must match IdealState
to ensure the segments are deleted from
- * server before moving to the next assignment.
- * For ERROR state in ExternalView, if using best-efforts, log a warning and
treat it as good state; if not, throw an
- * exception to abort the rebalance because we are not able to get out of
the ERROR state.
+ * Check if the external view has converged to the ideal state. See
`getNumRemainingSegmentsToProcess` for details on
+ * how the convergence is determined.
*/
private static boolean isExternalViewConverged(String tableNameWithType,
Map<String, Map<String, String>> externalViewSegmentStates,
Map<String, Map<String, String>> idealStateSegmentStates, boolean
lowDiskMode, boolean bestEfforts,
@Nullable Set<String> segmentsToMonitor, Logger tableRebalanceLogger) {
+ return getNumRemainingSegmentsToProcess(tableNameWithType,
externalViewSegmentStates, idealStateSegmentStates,
+ lowDiskMode, bestEfforts, segmentsToMonitor, tableRebalanceLogger,
true) == 0;
+ }
+
+ @VisibleForTesting
+ static int getNumRemainingSegmentsToProcess(String tableNameWithType,
+ Map<String, Map<String, String>> externalViewSegmentStates,
+ Map<String, Map<String, String>> idealStateSegmentStates, boolean
lowDiskMode, boolean bestEfforts,
+ @Nullable Set<String> segmentsToMonitor) {
+ return getNumRemainingSegmentsToProcess(tableNameWithType,
externalViewSegmentStates, idealStateSegmentStates,
+ lowDiskMode, bestEfforts, segmentsToMonitor, LOGGER, false);
+ }
+
+ /**
+ * Count the number of segments that are not in the expected state. If
`earlyReturn=true` it returns 1 as soon as
+ * the count becomes non-zero. This is used to check whether the
ExternalView has converged to the IdealState. The
+ * method checks the following:
+ * Only the segments in the IdealState and being monitored. Extra segments
in ExternalView are ignored
+ * because they are not managed by the rebalancer.
+ * For each segment, go through instances in the instance map from
IdealState and compare it with the one in
+ * ExternalView, and increment the number of remaining segments to process
if:
+ * - The instance appears in IS instance map, but there is no instance map
in EV, unless the IS instance state is
+ * OFFLINE
+ * - The instance appears in IS instance map is not in the EV instance map,
unless the IS instance state is OFFLINE
+ * - The instance has different states between IS and EV instance map,
unless the IS instance state is OFFLINE
Review Comment:
I think we almost never set a segment to OFFLINE state in IS, except when we
reset the segment. If the segment is OFFLINE in IS we assume that segment is
not needed to be online as IS is the expected state the segment should be in.
To remove segments, we delete them or remove the server instance for that
segment.
OFFLINE in EV but ONLINE in IS is different - indicating that the server
might be down or the segment hasn't completed state transition change yet. does
this help?
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