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[MINOR] OOC Fix Blocking Threads #2489

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Merged
janniklinde merged 1 commit into from
Jun 15, 2026
+6 −10
Merged

[MINOR] OOC Fix Blocking Threads #2489

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11 changes: 5 additions & 6 deletions src/main/java/org/apache/sysds/runtime/instructions/ooc/AggregateUnaryOOCInstruction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,6 @@
import org.apache.sysds.runtime.matrix.operators.AggregateUnaryOperator;
import org.apache.sysds.runtime.matrix.operators.Operator;
import org.apache.sysds.runtime.meta.DataCharacteristics;
import org.apache.sysds.runtime.ooc.stream.StreamContext;
import org.apache.sysds.runtime.util.IndexRange;

import java.util.HashMap;
Expand Down Expand Up @@ -119,9 +118,10 @@ public void processInstruction( ExecutionContext ec ) {
});

// global reduce
submitOOCTask(() -> {
IndexedMatrixValue partial;
while ((partial = qLocal.dequeue()) != LocalTaskQueue.NO_MORE_TASKS) {
addOutStream(qOut);
submitOOCTasks(qLocal, callback -> {
IndexedMatrixValue partial = callback.get();
synchronized(aggTracker) {
long idx = aggun.isRowAggregate() ? partial.getIndexes().getRowIndex() : partial.getIndexes()
.getColumnIndex();

Expand Down Expand Up @@ -150,8 +150,7 @@ public void processInstruction( ExecutionContext ec ) {
corrs.remove(idx);
}
}
qOut.closeInput();
}, new StreamContext().addOutStream(qOut));
}).thenRun(qOut::closeInput);
}
// full aggregation
else {
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5 changes: 1 addition & 4 deletions src/main/java/org/apache/sysds/runtime/instructions/ooc/OOCInstruction.java
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Expand Up @@ -1196,7 +1196,7 @@ protected <T> CompletableFuture<Void> submitOOCTasks(OOCStream<T> queue, Consume
}

protected CompletableFuture<Void> submitOOCTask(Runnable r, StreamContext ctx) {
ExecutorService pool = CommonThreadPool.get();
ExecutorService pool = CommonThreadPool.getDynamicPool();

@Baunsgaard Baunsgaard Jun 15, 2026

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This should not make a difference, The CommonThreadPool.get() should be the right way to get our shared threadpool that does get killed with the Java process.

@janniklinde janniklinde Jun 15, 2026

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This should make a difference because submitOOCTask may be used for blocking work (e.g. dequeue()). If we now use a fixed sized thread pool (which especially causes problems in environments with fewer enabled CPUs thus smaller number of workers on the default thread pool), this may block scheduled tasks from making progress that are needed for those workers to unblock.

@Baunsgaard Baunsgaard Jun 15, 2026

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okay did not know you had more tasks than threads in the pool.

final CompletableFuture<Void> future = new CompletableFuture<>();
try {
COMPUTE_IN_FLIGHT.incrementAndGet();
Expand All @@ -1220,9 +1220,6 @@ protected CompletableFuture<Void> submitOOCTask(Runnable r, StreamContext ctx) {
COMPUTE_IN_FLIGHT.decrementAndGet();
throw new DMLRuntimeException(ex);
}
finally {
pool.shutdown();
}

return future;
}
Expand Down
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