[
https://issues.apache.org/jira/browse/HADOOP-18296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18007638#comment-18007638
]
ASF GitHub Bot commented on HADOOP-18296:
-----------------------------------------
steveloughran commented on code in PR #7732:
URL: https://github.com/apache/hadoop/pull/7732#discussion_r2211186469
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/RawLocalFileSystem.java:
##########
@@ -400,7 +398,9 @@ private void initiateRead() {
for(int i = 0; i < ranges.size(); ++i) {
FileRange range = ranges.get(i);
buffers[i] = allocateRelease.getBuffer(false, range.getLength());
- channel.read(buffers[i], range.getOffset(), i, this);
+ final ByteBuffer buffer = buffers[i];
Review Comment:
lets me refer to it in the debug() statement
> 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.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: common-issues-h...@hadoop.apache.org
