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https://issues.apache.org/jira/browse/CASSANDRA-13760?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16148400#comment-16148400
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Jeff Jirsa commented on CASSANDRA-13760:
----------------------------------------
The unit test run was clean. The dtest run timed out before I saw the result,
so I've restarted it
[here|https://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-devbranch-dtest/254/]
I'm +1 on the patch as long as the dtest run comes back no worse than the other
trunk dtests.
I've made two small changes to the version I've uploaded as
{{0001-Presize-collections.patch}} :
On
{{src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java}}
, I added the expected size to the currGroup list made within the loop as well:
{code}
---
a/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
+++
b/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
@@ -539,7 +539,7 @@ public abstract class AbstractCompactionStrategy
Collections.sort(sortedSSTablesToGroup,
SSTableReader.sstableComparator);
Collection<Collection<SSTableReader>> groupedSSTables = new
ArrayList<>();
- Collection<SSTableReader> currGroup = new ArrayList<>();
+ Collection<SSTableReader> currGroup = new ArrayList<>(groupSize);
for (SSTableReader sstable : sortedSSTablesToGroup)
{
@@ -547,7 +547,7 @@ public abstract class AbstractCompactionStrategy
if (currGroup.size() == groupSize)
{
groupedSSTables.add(currGroup);
- currGroup = new ArrayList<>();
+ currGroup = new ArrayList<>(groupSize);
}
}
{code}
Similarly in
{{src/java/org/apache/cassandra/db/compaction/LeveledCompactionStrategy.java}}
, added the initial size to the nested group as well:
{code}
--- a/src/java/org/apache/cassandra/db/compaction/LeveledCompactionStrategy.java
+++ b/src/java/org/apache/cassandra/db/compaction/LeveledCompactionStrategy.java
@@ -223,14 +223,14 @@ public class LeveledCompactionStrategy extends
AbstractCompactionStrategy
for (Collection<SSTableReader> levelOfSSTables :
sstablesByLevel.values())
{
- Collection<SSTableReader> currGroup = new ArrayList<>();
+ Collection<SSTableReader> currGroup = new ArrayList<>(groupSize);
for (SSTableReader sstable : levelOfSSTables)
{
currGroup.add(sstable);
if (currGroup.size() == groupSize)
{
groupedSSTables.add(currGroup);
- currGroup = new ArrayList<>();
+ currGroup = new ArrayList<>(groupSize);
}
}
{code}
Other than that, +1, looks good.
> presize collections
> -------------------
>
> Key: CASSANDRA-13760
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13760
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Dave Brosius
> Assignee: Dave Brosius
> Priority: Trivial
> Fix For: 4.x
>
> Attachments: 0001-Presize-collections.patch, 13760.txt
>
>
> presize collections where sane, to avoid reallocs, or excess garbage
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