nsivabalan commented on code in PR #4913:
URL: https://github.com/apache/hudi/pull/4913#discussion_r1299397830
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hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/HoodieWriteHandle.java:
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@@ -273,4 +280,31 @@ protected static Option<IndexedRecord>
toAvroRecord(HoodieRecord record, Schema
return Option.empty();
}
}
+
+ protected class AppendLogWriteCallback implements HoodieLogFileWriteCallback
{
+ // here we distinguish log files created from log files being appended.
Considering following scenario:
+ // An appending task write to log file.
+ // (1) append to existing file file_instant_writetoken1.log.1
+ // (2) rollover and create file file_instant_writetoken2.log.2
+ // Then this task failed and retry by a new task.
+ // (3) append to existing file file_instant_writetoken1.log.1
+ // (4) rollover and create file file_instant_writetoken3.log.2
+ // finally file_instant_writetoken2.log.2 should not be committed to hudi,
we use marker file to delete it.
+ // keep in mind that log file is not always fail-safe unless it never roll
over
+
Review Comment:
I see. so its an issue even w/ S3 like systems?
Let me go over the scenario that you are referring to so that we are on same
page.
MDT disabled.
Writer1:
writer1 updates records in file group1 which already has a base file and 1
log file.
writer1 writes log file2 and logfile3 (due to spark task retries). but
ideally we just need only log file, i.e. log file2.
Writer2:
Concurrently tries to do a snapshot read from the same table concurrently.
Before reconcile step for writer1 could execute, hudi returns all 3 log files
(log file1, logfile2 and log file3) as part of FSView.
Writer1:
goes through the reconcile logic and deletes the extraneous log file. so log
file3 is deleted.
Writer2:
continues w/ actual read, where it hits file not found exception wrt log
file3.
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