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https://issues.apache.org/jira/browse/DRILL-5457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16035440#comment-16035440
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ASF GitHub Bot commented on DRILL-5457:
---------------------------------------
Github user Ben-Zvi commented on a diff in the pull request:
https://github.com/apache/drill/pull/822#discussion_r119954158
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/HashAggTemplate.java
---
@@ -400,114 +782,411 @@ public IterOutcome getOutcome() {
@Override
public int getOutputCount() {
- // return outputCount;
return lastBatchOutputCount;
}
@Override
public void cleanup() {
- if (htable != null) {
- htable.clear();
- htable = null;
- }
+ if ( schema == null ) { return; } // not set up; nothing to clean
+ for ( int i = 0; i < numPartitions; i++) {
+ if (htables[i] != null) {
+ htables[i].clear();
+ htables[i] = null;
+ }
+ if ( batchHolders[i] != null) {
+ for (BatchHolder bh : batchHolders[i]) {
+ bh.clear();
+ }
+ batchHolders[i].clear();
+ batchHolders[i] = null;
+ }
+
+ // delete any (still active) output spill file
+ if ( outputStream[i] != null && spillFiles[i] != null) {
+ try {
+ spillSet.delete(spillFiles[i]);
--- End diff --
Concurrent open files: While spilling, there is one per each (non-pristine)
spilling partition (yes, can be as high as 16, or even 32). Afterwards, they
are all closed; then for reading, each one gets opened; and though we process
one partition at a time, closing of all is postponed to the end, as the
processing code is unaware that the "incoming" actually comes from a spill
file.
About the limits: Seems that current defaults (e.g. 64K open files per
process) can serve us well for the foreseeable future. Intel just announced the
i9, where the top of the line CPU has 18 cores. Hence 1000s of concurrent
active same-process threads are not feasible anytime soon (think about context
switching).
> Support Spill to Disk for the Hash Aggregate Operator
> -----------------------------------------------------
>
> Key: DRILL-5457
> URL: https://issues.apache.org/jira/browse/DRILL-5457
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Relational Operators
> Affects Versions: 1.10.0
> Reporter: Boaz Ben-Zvi
> Assignee: Boaz Ben-Zvi
> Fix For: 1.11.0
>
>
> Support gradual spilling memory to disk as the available memory gets too
> small to allow in memory work for the Hash Aggregate Operator.
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