[jira] [Assigned] (HIVE-27884) LLAP: Reuse FileSystem objects from cache across different tasks in the same LLAP daemon

["László Bodor (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-27884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

László Bodor reassigned HIVE-27884:
-----------------------------------

    Assignee: László Bodor

> LLAP: Reuse FileSystem objects from cache across different tasks in the same LLAP daemon
> ----------------------------------------------------------------------------------------
>
>                 Key: HIVE-27884
>                 URL: https://issues.apache.org/jira/browse/HIVE-27884
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: László Bodor
>            Assignee: László Bodor
>            Priority: Major
>
> Originally, when the task runner was added to HIVE-10028 ([here|https://github.com/apache/hive/blob/23f40bd88043db3cb4efe3a763cbfd5c01a81d2f/llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskRunnerCallable.java#L202]), the FileSystem.closeAllForUGI was commented out for some reasons, and then, in the scope of HIVE-9898 it was simply added back, [here|https://github.com/apache/hive/commit/91c46a44dd9fbb68d01f22e93c4ce0931a4598e0#diff-270dbe6639879ca543ae21c44a239af6145390726d45fee832be809894bfc88eR236]
> A FileSystem.close call basically does the [following|https://github.com/apache/hadoop/blob/0c10bab7bb77aa4ea3ca26c899ab28131561e052/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java#L2700-L2710]:
> 1. delete all paths that were marked as delete-on-exit.
> 2. removes the instance from the cache
> I saw that we [call|https://github.com/apache/hive/blob/eb6f0b0c57dd55335927b7dde08cd47f4d00e74d/llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskRunnerCallable.java#L302] 
> {code}
> FileSystem.closeAllForUGI
> {code}
> at the end of all task attempts, so we almost completely disable hadoop's filesystem cache during a long-running LLAP daemon lifecycle
> some investigations on azure showed that creating a filesystem can be quite expensive, as it involves the recreation of a whole object hierarchy like:
> {code}
> AzureBlobFileSystem -> AzureBlobFileSystemStore --> AbfsClient -> TokenProvider(MsiTokenProvider)
> {code}
> which ends up pinging the token auth endpoint of azure, leading to e.g. a HTTP response 429
> We need to check whether we can remove this closeAllForUGI in LLAP, additionally check and remove all deleteOnExit calls that belong to hadoop FileSystem objects (doesn't necessarily apply to java.io.File.deleteOnExit calls):
> {code}
> grep -iRH "deleteOnExit" --include="*.java" | grep -v "test"
> ...
> ql/src/java/org/apache/hadoop/hive/ql/exec/FileSinkOperator.java:        // in recent hadoop versions, use deleteOnExit to clean tmp files.
> ql/src/java/org/apache/hadoop/hive/ql/exec/FileSinkOperator.java:        autoDelete = fs.deleteOnExit(fsp.outPaths[filesIdx]);
> ql/src/java/org/apache/hadoop/hive/ql/exec/repl/bootstrap/load/util/PathInfo.java:        fileSystem.deleteOnExit(dir);
> ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/RowContainer.java:      parentDir.deleteOnExit();
> ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/RowContainer.java:      tmpFile.deleteOnExit();
> ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/KeyValueContainer.java:        parentDir.deleteOnExit();
> ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/KeyValueContainer.java:        tmpFile.deleteOnExit();
> ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/ObjectContainer.java:        tmpFile.deleteOnExit();
> ql/src/java/org/apache/hadoop/hive/ql/exec/AbstractFileMergeOperator.java:        autoDelete = fs.deleteOnExit(outPath);
> {code}
> I believe deleteOnExit is fine if we don't want to bother with removing temp files, however, these deletions might want to go to a more hive-specific scope if we want to really reuse cached filesystems in a safe manner.



--
This message was sent by Atlassian Jira
(v8.20.10#820010)