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Manoj Govindassamy commented on HDFS-11267: ------------------------------------------- The fix for HDFS-11251 (ConcurrentModificationException during DataNode#refreshVolumes) making the {{Storage#storageDirs}} a {{CopyOnWriteArrayList}} is needed for this bug. On top of HDFS-11251 fix, we need more clean up patches. > Avoid redefinition of storageDirs in NNStorage and cleanup its accessors in > Storage > ----------------------------------------------------------------------------------- > > Key: HDFS-11267 > URL: https://issues.apache.org/jira/browse/HDFS-11267 > Project: Hadoop HDFS > Issue Type: Bug > Affects Versions: 3.0.0-alpha1 > Reporter: Manoj Govindassamy > Assignee: Manoj Govindassamy > > In the abstract class {{Storage}}, {{storageDirs}} is a protected variable > and all its derived classes like {{NNStorage}}, {{JNStorage}}, > {{DataStorage}}.. are iterating over this non-thread safe variable without > any proper locks. Any parallel modification operation like add or remove > volume can mutate the backing storageDirs list and any iterators on this list > around the same time can face {{ConcurrentModificationException}}. It would > be good to make the variable private and restrict the access via getters and > setters. Any thread safe restriction need to be done can then be placed on > the parent class only. > Also, {{NNStorage}} redefines parent class Storage's {{storageDirs}}, making > it inconsistent with other derived classes. Would be cleaner if {{NNStorage}} > can avoid re-defining it locally. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org