StefanRRichter commented on a change in pull request #8263:
[FLINK-12296][StateBackend]Data loss silently in RocksDBStateBackend because of
local directory collision
URL: https://github.com/apache/flink/pull/8263#discussion_r279304144
##########
File path:
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/snapshot/RocksIncrementalSnapshotStrategy.java
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@@ -184,17 +189,19 @@ private SnapshotDirectory
prepareLocalSnapshotDirectory(long checkpointId) throw
LocalRecoveryDirectoryProvider directoryProvider =
localRecoveryConfig.getLocalStateDirectoryProvider();
File directory =
directoryProvider.subtaskSpecificCheckpointDirectory(checkpointId);
- if (directory.exists()) {
- FileUtils.deleteDirectory(directory);
- }
-
- if (!directory.mkdirs()) {
+ if (!directory.exists() && !directory.mkdirs()) {
throw new IOException("Local state base
directory for checkpoint " + checkpointId +
" already exists: " + directory);
}
// introduces an extra directory because RocksDB wants
a non-existing directory for native checkpoints.
- File rdbSnapshotDir = new File(directory, "rocks_db");
+ // append operatorIdentifier here to solve directory
collision problem when two stateful operators chained in one task.
+ String subDir =
operatorIdentifier.replaceAll("[^a-zA-Z0-9\\-]", "_");
Review comment:
I would have suggested to pass the operator id into the backend instead of
string operations, but you are right, using the backend UUID can also be used
to fix the problem. The only downside is that we can not conclude anymore about
which opertor the directory belongs to. But that might be ok.
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