ngsg commented on code in PR #5478:
URL: https://github.com/apache/hive/pull/5478#discussion_r2018602715
##########
ql/src/java/org/apache/hadoop/hive/ql/exec/GroupByOperator.java:
##########
@@ -389,14 +390,14 @@ protected void initializeOp(Configuration hconf) throws
HiveException {
isLlap = LlapDaemonInfo.INSTANCE.isLlap();
numExecutors = isLlap ? LlapDaemonInfo.INSTANCE.getNumExecutors() : 1;
firstRow = true;
+ memoryMXBean = ManagementFactory.getMemoryMXBean();
+ maxMemory = isTez ? getConf().getMaxMemoryAvailable() :
memoryMXBean.getHeapMemoryUsage().getMax();
Review Comment:
I think we could use a number less than `operators.size()` since not all
operators require significant memory that should be managed by
`getMaxMemoryAvailable()`. For instance, we can likely ignore select and filter
operators, as they behave more like fire-and-forget operations and do not
consume much memory. Given that `OperatorDesc.getMaxMemoryAvailable()` is
referred by MapJoin, ReduceSink (with TopN), and GroupBy (with Hash Aggregate
Mode), I think #MapJoin + #(RS with TopN) + #(GBY with HashMode) + 1(for the
rest) could be a candidate.
##########
ql/src/java/org/apache/hadoop/hive/ql/exec/GroupByOperator.java:
##########
@@ -389,14 +390,14 @@ protected void initializeOp(Configuration hconf) throws
HiveException {
isLlap = LlapDaemonInfo.INSTANCE.isLlap();
numExecutors = isLlap ? LlapDaemonInfo.INSTANCE.getNumExecutors() : 1;
firstRow = true;
+ memoryMXBean = ManagementFactory.getMemoryMXBean();
+ maxMemory = isTez ? getConf().getMaxMemoryAvailable() :
memoryMXBean.getHeapMemoryUsage().getMax();
Review Comment:
I think we could use a number less than `operators.size()` since not all
operators require significant memory that should be managed by
`getMaxMemoryAvailable()`. For instance, we can likely ignore select and filter
operators, as they behave more like fire-and-forget operations and do not
consume much memory. Given that `OperatorDesc.getMaxMemoryAvailable()` is
referred by MapJoin, ReduceSink (with TopN), and GroupBy (with Hash Aggregate
Mode), I think #MapJoin + #(RS with TopN) + #(GBY with HashMode) + 1(for the
rest) could be a candidate.
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