johnyangk commented on a change in pull request #72: [Nemo-59] Skewed
data-aware executor allocation
URL: https://github.com/apache/incubator-nemo/pull/72#discussion_r200861904
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File path:
runtime/common/src/main/java/edu/snu/nemo/runtime/common/optimizer/pass/runtime/DataSkewRuntimePass.java
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@@ -75,52 +81,75 @@ public PhysicalPlan apply(final PhysicalPlan originalPlan,
.collect(Collectors.toList());
// Get number of evaluators of the next stage (number of blocks).
- final Integer taskListSize =
optimizationEdges.stream().findFirst().orElseThrow(() ->
+ final Integer reducerTaskNum =
optimizationEdges.stream().findFirst().orElseThrow(() ->
new RuntimeException("optimization edges are
empty")).getDst().getTaskIds().size();
// Calculate keyRanges.
- final List<KeyRange> keyRanges = calculateHashRanges(metricData.right(),
taskListSize);
+ final List<KeyRange> keyRanges = calculateHashRanges(metricData.right(),
reducerTaskNum);
// Overwrite the previously assigned hash value range in the physical DAG
with the new range.
optimizationEdges.forEach(optimizationEdge -> {
// Update the information.
- final List<KeyRange> taskIdxToHashRange = new ArrayList<>();
- IntStream.range(0, taskListSize).forEach(i ->
taskIdxToHashRange.add(keyRanges.get(i)));
+ final Map<Integer, KeyRange> taskIdxToHashRange = new HashMap<>();
+ for (int taskIdx = 0; taskIdx < reducerTaskNum; taskIdx++) {
+ taskIdxToHashRange.put(taskIdx, keyRanges.get(taskIdx));
+ }
optimizationEdge.setTaskIdxToKeyRange(taskIdxToHashRange);
});
return new PhysicalPlan(originalPlan.getId(), physicalDAGBuilder.build());
}
+ private boolean containsSkewedHash(final List<Integer> skewedHashes,
Review comment:
Can you provide a definition of the 'skewed hash' in the class-level comment?
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