Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/822#discussion_r118812287
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/HashAggTemplate.java
---
@@ -266,17 +508,138 @@ public void setup(HashAggregate hashAggrConfig,
HashTableConfig htConfig, Fragme
}
}
- ChainedHashTable ht =
+ spillSet = new SpillSet(context,hashAggrConfig,
UserBitShared.CoreOperatorType.HASH_AGGREGATE);
+ baseHashTable =
new ChainedHashTable(htConfig, context, allocator, incoming, null
/* no incoming probe */, outgoing);
- this.htable = ht.createAndSetupHashTable(groupByOutFieldIds);
-
+ this.groupByOutFieldIds = groupByOutFieldIds; // retain these for
delayedSetup, and to allow recreating hash tables (after a spill)
numGroupByOutFields = groupByOutFieldIds.length;
- batchHolders = new ArrayList<BatchHolder>();
- // First BatchHolder is created when the first put request is received.
doSetup(incoming);
}
+ /**
+ * Delayed setup are the parts from setup() that can only be set after
actual data arrives in incoming
+ * This data is used to compute the number of partitions.
+ */
+ private void delayedSetup() {
+
+ // Set the number of partitions from the configuration (raise to a
power of two, if needed)
+ numPartitions =
context.getConfig().getInt(ExecConstants.HASHAGG_NUM_PARTITIONS_KEY);
+ if ( numPartitions == 1 ) {
+ canSpill = false;
+ logger.warn("Spilling was disabled");
+ }
+ while (Integer.bitCount(numPartitions) > 1) { // in case not a power
of 2
+ numPartitions++;
+ }
+ if ( schema == null ) { estMaxBatchSize = 0; } // incoming was an
empty batch
+ else {
+ // Estimate the max batch size; should use actual data (e.g. lengths
of varchars)
+ updateEstMaxBatchSize(incoming);
+ }
+ long memAvail = memoryLimit - allocator.getAllocatedMemory();
+ if ( !canSpill ) { // single phase, or spill disabled by configuation
+ numPartitions = 1; // single phase should use only a single
partition (to save memory)
+ } else { // two phase
+ // Adjust down the number of partitions if needed - when the memory
available can not hold as
+ // many batches (configurable option), plus overhead (e.g. hash
table, links, hash values))
+ while ( numPartitions * ( estMaxBatchSize * minBatchesPerPartition +
8 * 1024 * 1024) > memAvail ) {
+ numPartitions /= 2;
+ if ( numPartitions < 2) {
+ if ( is2ndPhase ) { canSpill = false; } // 2nd phase needs at
least 2 to make progress
--- End diff --
Maybe log the problem to help track down issues on a production system?
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