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https://issues.apache.org/jira/browse/HDFS-15798?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17276247#comment-17276247
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Stephen O'Donnell commented on HDFS-15798:
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I just tried running the test again and it does pass when the code change has
been reverted, and the test change is left in place. Last week, I am fairly
sure I got it to fail, but I have tried several times now and it always passes.
Searching the test output, the string "Failed to reconstruct striped block"
which should be logged after the exception occurs is not appearing. Therefore
it seems the test is not triggering the exception somehow, and therefore the
exception condition is not getting tested.
> EC: Reconstruct task failed, and It would be XmitsInProgress of DN has
> negative number
> --------------------------------------------------------------------------------------
>
> Key: HDFS-15798
> URL: https://issues.apache.org/jira/browse/HDFS-15798
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: huhaiyang
> Assignee: huhaiyang
> Priority: Major
> Attachments: HDFS-15798.001.patch, HDFS-15798.002.patch
>
>
> The EC reconstruct task failed, and the decrementXmitsInProgress of
> processErasureCodingTasks operation abnormal value ;
> It would be XmitsInProgress of DN has negative number, it affects NN chooses
> pending tasks based on the ratio between the lengths of replication and
> erasure-coded block queues.
> {code:java}
> // 1.ErasureCodingWorker.java
> public void processErasureCodingTasks(
> Collection<BlockECReconstructionInfo> ecTasks) {
> for (BlockECReconstructionInfo reconInfo : ecTasks) {
> int xmitsSubmitted = 0;
> try {
> ...
> // It may throw IllegalArgumentException from task#stripedReader
> // constructor.
> final StripedBlockReconstructor task =
> new StripedBlockReconstructor(this, stripedReconInfo);
> if (task.hasValidTargets()) {
> // See HDFS-12044. We increase xmitsInProgress even the task is only
> // enqueued, so that
> // 1) NN will not send more tasks than what DN can execute and
> // 2) DN will not throw away reconstruction tasks, and instead keeps
> // an unbounded number of tasks in the executor's task queue.
> xmitsSubmitted = Math.max((int)(task.getXmits() * xmitWeight), 1);
> getDatanode().incrementXmitsInProcess(xmitsSubmitted); // task start
> increment
> stripedReconstructionPool.submit(task);
> } else {
> LOG.warn("No missing internal block. Skip reconstruction for task:{}",
> reconInfo);
> }
> } catch (Throwable e) {
> getDatanode().decrementXmitsInProgress(xmitsSubmitted); // task failed
> decrement, XmitsInProgress is decremented by the previous value
> LOG.warn("Failed to reconstruct striped block {}",
> reconInfo.getExtendedBlock().getLocalBlock(), e);
> }
> }
> }
> // 2.StripedBlockReconstructor.java
> public void run() {
> try {
> initDecoderIfNecessary();
> ...
> } catch (Throwable e) {
> LOG.warn("Failed to reconstruct striped block: {}", getBlockGroup(), e);
> getDatanode().getMetrics().incrECFailedReconstructionTasks();
> } finally {
> float xmitWeight = getErasureCodingWorker().getXmitWeight();
> // if the xmits is smaller than 1, the xmitsSubmitted should be set to 1
> // because if it set to zero, we cannot to measure the xmits submitted
> int xmitsSubmitted = Math.max((int) (getXmits() * xmitWeight), 1);
> getDatanode().decrementXmitsInProgress(xmitsSubmitted); // task complete
> decrement
> ...
> }
> }{code}
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