[
https://issues.apache.org/jira/browse/HDFS-16939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17696652#comment-17696652
]
ASF GitHub Bot commented on HDFS-16939:
---------------------------------------
zhangshuyan0 commented on code in PR #5450:
URL: https://github.com/apache/hadoop/pull/5450#discussion_r1125809336
##########
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:
Thanks for your suggestion, I'll make both `boolean remove(BlockInfo block,
int priLevel, int oldExpectedReplicas)` and `boolean remove(BlockInfo block,
int priLevel)` synchronized to ensure correctness.
However, I think you misunderstood the semantics of `synchronized` a method.
Refer to [java
doc](https://docs.oracle.com/javase/tutorial/essential/concurrency/syncmeth.html):
> When one thread is executing a synchronized method for an object, all
other threads that invoke synchronized methods for the same object block
(suspend execution) until the first thread is done with the object.
> 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.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
