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https://issues.apache.org/jira/browse/HADOOP-18296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17959762#comment-17959762
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ASF GitHub Bot commented on HADOOP-18296:
-----------------------------------------
steveloughran commented on code in PR #7732:
URL: https://github.com/apache/hadoop/pull/7732#discussion_r2140379298
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/LocalFileSystemConfigKeys.java:
##########
@@ -42,5 +42,12 @@ public class LocalFileSystemConfigKeys extends
CommonConfigurationKeys {
public static final String LOCAL_FS_CLIENT_WRITE_PACKET_SIZE_KEY =
"file.client-write-packet-size";
public static final int LOCAL_FS_CLIENT_WRITE_PACKET_SIZE_DEFAULT =
64*1024;
+
+ /**
+ * Verify checksums on read -default is true.
+ * <p>
+ * {@value}.
+ */
+ public static final String LOCAL_FS_VERIFY_CHECKSUM = "file.verify-checksum";
Review Comment:
rename fs.file.checksum.very and delclare in core-defaults to make more
visible
> Memory fragmentation in ChecksumFileSystem Vectored IO implementation.
> ----------------------------------------------------------------------
>
> Key: HADOOP-18296
> URL: https://issues.apache.org/jira/browse/HADOOP-18296
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: common
> Affects Versions: 3.4.0
> Reporter: Mukund Thakur
> Assignee: Steve Loughran
> Priority: Minor
> Labels: fs, pull-request-available
>
> As we have implemented merging of ranges in the ChecksumFSInputChecker
> implementation of vectored IO api, it can lead to memory fragmentation. Let
> me explain by example.
>
> Suppose client requests for 3 ranges.
> 0-500, 700-1000 and 1200-1500.
> Now because of merging, all the above ranges will get merged into one and we
> will allocate a big byte buffer of 0-1500 size but return sliced byte buffers
> for the desired ranges.
> Now once the client is done reading all the ranges, it will only be able to
> free the memory for requested ranges and memory of the gaps will never be
> released for eg here (500-700 and 1000-1200).
>
> Note this only happens for direct byte buffers.
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