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Mukund Thakur commented on HADOOP-18296: ---------------------------------------- {quote}Mukund, do we actually need to coalesce ranges on local fs reads? because it is all local. we can just push out a list of independent regions. {quote} We are not merging during default vectored read and Raw local FS read implementation. Although we are merging during the checksum FS. {quote}we do still need to deal with failures by adding the ability to return buffers to any pool on failure. {quote} if the read failed for any range, future.get() will throw an exception, and thus the caller can return it to the pool. As per the design, the management of buffers in a pool is being handled by the caller of API. > 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 > Priority: Minor > Labels: fs > > 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