Chen He created HADOOP-12046:
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Summary: Avoid creating "._COPYING_" temporary file when copying
file to Swift file system
Key: HADOOP-12046
URL: https://issues.apache.org/jira/browse/HADOOP-12046
Project: Hadoop Common
Issue Type: New Feature
Affects Versions: 2.7.0
Reporter: Chen He
Assignee: Chen He
When copy file from HDFS or local to another file system implementation, in
CommandWithDestination.java, it creates a temp file by adding suffix
"._COPYING_". Once file is successfully copied, it will remove the suffix by
rename().
try {
PathData tempTarget = target.suffix("._COPYING_");
targetFs.setWriteChecksum(writeChecksum);
targetFs.writeStreamToFile(in, tempTarget, lazyPersist);
targetFs.rename(tempTarget, target);
} finally {
targetFs.close(); // last ditch effort to ensure temp file is removed
}
It is not costly in HDFS. However, if copy to Swift file system, the rename
process is to create a new file. It is not efficient if users copy a lot of
files to swift file system. I did some tests, for a 1G file copying to swift,
it will take 10% more time. We should only do the copy one time for Swift file
system. Changes should be limited to the Swift driver level.
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