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https://issues.apache.org/jira/browse/HDFS-16939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17696180#comment-17696180
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ASF GitHub Bot commented on HDFS-16939:
---------------------------------------
saxenapranav commented on code in PR #5450:
URL: https://github.com/apache/hadoop/pull/5450#discussion_r1124561712
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/LowRedundancyBlocks.java:
##########
@@ -369,7 +369,7 @@ synchronized boolean remove(BlockInfo block,
* @return true if the block was found and removed from one of the priority
* queues
*/
- boolean remove(BlockInfo block, int priLevel) {
+ synchronized boolean remove(BlockInfo block, int priLevel) {
Review Comment:
> > should `boolean remove(BlockInfo block, int priLevel, int
oldExpectedReplicas)` be made synchronized instead. Its other callers are
synchronized methods:
>
> Sorry I don't quite understand. Since the callers are already
synchronized, why is it necessary to made `boolean remove(BlockInfo block, int
priLevel, int oldExpectedReplicas)` synchronized?
Since `boolean remove(BlockInfo block, int priLevel)` forwards the call to
`boolean remove(BlockInfo block, int priLevel, int oldExpectedReplicas)`, I am
suggesting that lets make `boolean remove(BlockInfo block, int priLevel, int
oldExpectedReplicas)` synchronized instead.
Callers of `boolean remove(BlockInfo block, int priLevel, int
oldExpectedReplicas)` are synchronized means that we can have `boolean
remove(BlockInfo block, int priLevel, int oldExpectedReplicas)` as synchronized
without any perf-loss.
> Fix the thread safety bug in LowRedundancyBlocks
> ------------------------------------------------
>
> Key: HDFS-16939
> URL: https://issues.apache.org/jira/browse/HDFS-16939
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namanode
> Reporter: Shuyan Zhang
> Assignee: Shuyan Zhang
> Priority: Major
> Labels: pull-request-available
>
> The remove method in LowRedundancyBlocks is not protected by synchronized.
> This method is private and is called by BlockManager. As a result,
> priorityQueues has the risk of being accessed concurrently by multiple
> threads.
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