Only map the non-zero values

Author: joegallo

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/TransportClusterStatsAction.java

@@ -264,7 +264,8 @@ protected ClusterStatsNodeResponse nodeOperation(ClusterStatsNodeRequest nodeReq
         List<ShardStats> shardsStats = new ArrayList<>();
         for (IndexService indexService : indicesService) {
             for (IndexShard indexShard : indexService) {
-                long sharedRam = shardIdToSharedRam.get(indexShard.shardId());
+                // get the shared ram for this shard id (or zero if there's nothing in the map)
+                long sharedRam = shardIdToSharedRam.getOrDefault(indexShard.shardId(), 0L);
                 cancellableTask.ensureNotCancelled();
                 if (indexShard.routingEntry() != null && indexShard.routingEntry().active()) {
                     // only report on fully started shards

server/src/main/java/org/elasticsearch/indices/IndicesQueryCache.java

@@ -80,10 +80,13 @@ public static Map<ShardId, Long> getSharedRamForAllShards(IndicesService indices
                     indexShard.shardId(),
                     cacheTotals
                 );
-                shardIdToSharedRam.put(indexShard.shardId(), sharedRam);
+                // as a size optimization, only store non-zero values in the map
+                if (sharedRam > 0L) {
+                    shardIdToSharedRam.put(indexShard.shardId(), sharedRam);
+                }
             }
         }
-        return shardIdToSharedRam;
+        return Collections.unmodifiableMap(shardIdToSharedRam);
     }
 
     public long getCacheSizeForShard(ShardId shardId) {

server/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -524,7 +524,8 @@ static Map<Index, List<IndexShardStats>> statsByShard(final IndicesService indic
         final Map<Index, List<IndexShardStats>> statsByShard = new HashMap<>();
         for (final IndexService indexService : indicesService) {
             for (final IndexShard indexShard : indexService) {
-                long sharedRam = shardIdToSharedRam.get(indexShard.shardId());
+                // get the shared ram for this shard id (or zero if there's nothing in the map)
+                long sharedRam = shardIdToSharedRam.getOrDefault(indexShard.shardId(), 0L);
                 try {
                     final IndexShardStats indexShardStats = indicesService.indexShardStats(indicesService, indexShard, flags, sharedRam);
                     if (indexShardStats == null) {