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https://issues.apache.org/jira/browse/HDFS-12866?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wei-Chiu Chuang resolved HDFS-12866.
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Resolution: Duplicate
Resolve as it duplicates HDFS-11225
> Recursive delete of a large directory or snapshot makes namenode unresponsive
> -----------------------------------------------------------------------------
>
> Key: HDFS-12866
> URL: https://issues.apache.org/jira/browse/HDFS-12866
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Reporter: Yongjun Zhang
> Priority: Major
>
> Currently file/directory deletion happens in two steps (see
> {{FSNamesystem#delete(String src, boolean recursive, boolean logRetryCache)}}:
> # Do the following under fsn write lock and release the lock afterwards
> ** 1.1 recursively traverse the target, collect INodes and all blocks to be
> deleted
> ** 1.2 delete all INodes
> # Delete the blocks to be deleted incrementally, chunk by chunk. That is, in
> a loop, do:
> ** acquire fsn write lock,
> ** delete chunk of blocks
> ** release fsn write lock
> Breaking the deletion to two steps is to not hold the fsn write lock for too
> long thus making NN not responsive. However, even with this, for deleting
> large directory, or deleting snapshot that has a lot of contents, step 1
> itself would takes long time thus still hold the fsn write lock for too long
> and make NN not responsive.
> A possible solution would be to add one more sub step in step 1, and only
> hold fsn write lock in sub step 1.1:
> * 1.1. hold the fsn write lock, disconnect the target to be deleted from its
> parent dir, release the lock
> * 1.2 recursively traverse the target, collect INodes and all blocks to be
> deleted
> * 1.3 delete all INodes
> Then do step 2.
> This means, any operations on any file/dir need to check if its ancestor is
> deleted (ancestor is disconnected), similar to what's done in
> FSNamesystem#isFileDeleted method.
> I'm throwing the thought here for further discussion. Welcome comments and
> inputs.
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