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https://issues.apache.org/jira/browse/HDFS-17052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17737951#comment-17737951
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ASF GitHub Bot commented on HDFS-17052:
---------------------------------------
zhangshuyan0 commented on code in PR #5759:
URL: https://github.com/apache/hadoop/pull/5759#discussion_r1244628377
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyRackFaultTolerant.java:
##########
@@ -192,11 +192,19 @@ private void chooseEvenlyFromRemainingRacks(Node writer,
} finally {
excludedNodes.addAll(newExcludeNodes);
}
+ if (numResultsOflastChoose == results.size()) {
+ Map<String, Integer> nodesPerRack = new HashMap<>();
+ for (DatanodeStorageInfo dsInfo : results) {
+ String rackName =
dsInfo.getDatanodeDescriptor().getNetworkLocation();
+ nodesPerRack.merge(rackName, 1, Integer::sum);
+ }
+ bestEffortMaxNodesPerRack = Collections.max(nodesPerRack.values());
Review Comment:
Is it possible to introduce infinite loops here? If each rack already has
one chosen node and `bestEffortMaxNodesPerRack` is 2, and no datanode can be
chosen now, then `bestEffortMaxNodesPerRack` will change to 1 after line 201,
which may cause an infinite loop. So the calculation of the maximum value
should consider the old value of `bestEffortMaxNodesPerRack` to insure increase.
> Erasure coding reconstruction failed when num of storageType rack NOT enough
> ----------------------------------------------------------------------------
>
> Key: HDFS-17052
> URL: https://issues.apache.org/jira/browse/HDFS-17052
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ec
> Affects Versions: 3.4.0
> Reporter: Hualong Zhang
> Assignee: Hualong Zhang
> Priority: Major
> Labels: pull-request-available
> Attachments: failed reconstruction ec in same rack-1.png, write ec in
> same rack.png
>
>
> When writing EC data, if the number of racks matching the storageType is
> insufficient, more than one block are allowed to be written to the same rack
> !write ec in same rack.png|width=962,height=604!
>
>
>
> However, during EC block recovery, it is not possible to recover on the same
> rack, which deviates from the expected behavior.
> !failed reconstruction ec in same rack-1.png|width=946,height=413!
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