Ben-Zvi commented on a change in pull request #1408: DRILL-6453: Resolve
deadlock when reading from build and probe sides simultaneously in HashJoin
URL: https://github.com/apache/drill/pull/1408#discussion_r208401852
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/HashJoinBatch.java
##########
@@ -248,95 +257,134 @@ protected void buildSchema() throws
SchemaChangeException {
}
}
- @Override
- protected boolean prefetchFirstBatchFromBothSides() {
- if (leftUpstream != IterOutcome.NONE) {
- // We can only get data if there is data available
- leftUpstream = sniffNonEmptyBatch(leftUpstream, LEFT_INDEX, left);
- }
-
- if (rightUpstream != IterOutcome.NONE) {
- // We can only get data if there is data available
- rightUpstream = sniffNonEmptyBatch(rightUpstream, RIGHT_INDEX, right);
- }
-
- buildSideIsEmpty = rightUpstream == IterOutcome.NONE;
-
- if (verifyOutcomeToSetBatchState(leftUpstream, rightUpstream)) {
- // For build side, use aggregate i.e. average row width across batches
- batchMemoryManager.update(LEFT_INDEX, 0);
- batchMemoryManager.update(RIGHT_INDEX, 0, true);
-
- logger.debug("BATCH_STATS, incoming left: {}",
batchMemoryManager.getRecordBatchSizer(LEFT_INDEX));
- logger.debug("BATCH_STATS, incoming right: {}",
batchMemoryManager.getRecordBatchSizer(RIGHT_INDEX));
-
- // Got our first batche(s)
- state = BatchState.FIRST;
- return true;
- } else {
- return false;
- }
- }
/**
* Sniffs all data necessary to construct a schema.
* @return True if all the data necessary to construct a schema has been
retrieved. False otherwise.
*/
private boolean sniffNewSchemas() {
+ leftUpstream = sniffNewSchema(LEFT_INDEX,
+ left,
+ () -> probeSchema = left.getSchema());
+
+ rightUpstream = sniffNewSchema(RIGHT_INDEX,
+ right,
+ () -> {
+ // We need to have the schema of the build side even when the build
side is empty
+ buildSchema = right.getSchema();
+ // position of the new "column" for keeping the hash values (after the
real columns)
+ rightHVColPosition = right.getContainer().getNumberOfColumns();
+ });
+
+ // Left and right sides must return a valid response and both sides cannot
be NONE.
+ return (!leftUpstream.isError() && !rightUpstream.isError()) &&
+ (leftUpstream != IterOutcome.NONE && rightUpstream != IterOutcome.NONE);
+ }
+
+ private IterOutcome sniffNewSchema(final int index,
+ final RecordBatch batch,
+ final Runnable schemaSetter) {
Review comment:
The use of lambda function as a parameter just makes this code harder to
read, and adds no real value.
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