StephanEwen commented on a change in pull request #7313:
[FLINK-11116][fs-connector] Removed randomness from HDFS and Local fs writers.
URL: https://github.com/apache/flink/pull/7313#discussion_r249832214
##########
File path:
flink-filesystems/flink-hadoop-fs/src/main/java/org/apache/flink/runtime/fs/hdfs/HadoopRecoverableWriter.java
##########
@@ -121,24 +127,14 @@ public boolean supportsResume() {
return true;
}
- @VisibleForTesting
- static org.apache.hadoop.fs.Path generateStagingTempFilePath(
- org.apache.hadoop.fs.FileSystem fs,
- org.apache.hadoop.fs.Path targetFile) throws
IOException {
-
+ private static org.apache.hadoop.fs.Path
generateStagingTempFilePath(org.apache.hadoop.fs.Path targetFile) {
checkArgument(targetFile.isAbsolute(), "targetFile must be
absolute");
final org.apache.hadoop.fs.Path parent = targetFile.getParent();
final String name = targetFile.getName();
checkArgument(parent != null, "targetFile must not be the root
directory");
- while (true) {
- org.apache.hadoop.fs.Path candidate = new
org.apache.hadoop.fs.Path(
- parent, "." + name + ".inprogress." +
UUID.randomUUID().toString());
- if (!fs.exists(candidate)) {
- return candidate;
- }
- }
+ return new org.apache.hadoop.fs.Path(parent, "." + name +
".inprogress");
Review comment:
I added this as a simple way to avoid collisions, without relying on the
semantics of the code that invokes this.
I would try and think through what happens after a failure/recovery when an
old task (running on a network-partitioned TM that has not yet cancelled) is
still writing to the same file as a recovered task. Can that happen? If yes,
what is the behavior then? Do we reduce the guarantees in that case? The
partitioned TM should not be able to commit a checkpoint (to not roll over to a
proper file), but can it mess up / overwrite the staging contents? My initial
thought is that it probably could - not 100% sure though how HDFS leases would
behave then, could they prevent that?
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