johnyangk closed pull request #161: [NEMO-300] Fix starvation when handling
multiple pending data fetchers
URL: https://github.com/apache/incubator-nemo/pull/161
This is a PR merged from a forked repository.
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diff --git
a/runtime/executor/src/main/java/org/apache/nemo/runtime/executor/task/TaskExecutor.java
b/runtime/executor/src/main/java/org/apache/nemo/runtime/executor/task/TaskExecutor.java
index b08b12a25..af3197999 100644
---
a/runtime/executor/src/main/java/org/apache/nemo/runtime/executor/task/TaskExecutor.java
+++
b/runtime/executor/src/main/java/org/apache/nemo/runtime/executor/task/TaskExecutor.java
@@ -461,31 +461,34 @@ private boolean handleDataFetchers(final
List<DataFetcher> fetchers) {
final Iterator<DataFetcher> pendingIterator = pendingFetchers.iterator();
final long currentTime = System.currentTimeMillis();
- // We check pending data every polling interval
- while (pendingIterator.hasNext()
- && isPollingTime(pollingInterval, currentTime, prevPollingTime)) {
+
+
+ if (isPollingTime(pollingInterval, currentTime, prevPollingTime)) {
+ // We check pending data every polling interval
prevPollingTime = currentTime;
- final DataFetcher dataFetcher = pendingIterator.next();
- try {
- final Object element = dataFetcher.fetchDataElement();
- onEventFromDataFetcher(element, dataFetcher);
+ while (pendingIterator.hasNext()) {
+ final DataFetcher dataFetcher = pendingIterator.next();
+ try {
+ final Object element = dataFetcher.fetchDataElement();
+ onEventFromDataFetcher(element, dataFetcher);
+
+ // We processed data. This means the data fetcher is now available.
+ // Add current data fetcher to available
+ pendingIterator.remove();
+ if (!(element instanceof Finishmark)) {
+ availableFetchers.add(dataFetcher);
+ }
- // We processed data. This means the data fetcher is now available.
- // Add current data fetcher to available
- pendingIterator.remove();
- if (!(element instanceof Finishmark)) {
- availableFetchers.add(dataFetcher);
+ } catch (final NoSuchElementException e) {
+ // The current data fetcher is still pending.. try next data
fetcher
+ } catch (final IOException e) {
+ // IOException means that this task should be retried.
+ taskStateManager.onTaskStateChanged(TaskState.State.SHOULD_RETRY,
+ Optional.empty(),
Optional.of(TaskState.RecoverableTaskFailureCause.INPUT_READ_FAILURE));
+ LOG.error("{} Execution Failed (Recoverable: input read failure)!
Exception: {}", taskId, e);
+ return false;
}
-
- } catch (final NoSuchElementException e) {
- // The current data fetcher is still pending.. try next data fetcher
- } catch (final IOException e) {
- // IOException means that this task should be retried.
- taskStateManager.onTaskStateChanged(TaskState.State.SHOULD_RETRY,
- Optional.empty(),
Optional.of(TaskState.RecoverableTaskFailureCause.INPUT_READ_FAILURE));
- LOG.error("{} Execution Failed (Recoverable: input read failure)!
Exception: {}", taskId, e);
- return false;
}
}
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