[jira] [Created] (FLINK-29577) Disable rocksdb wal when restore from full snapshot

["Cai Liuyang (Jira)" <ji...@apache.org>]

Cai Liuyang created FLINK-29577:
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             Summary: Disable rocksdb wal when restore from full snapshot
                 Key: FLINK-29577
                 URL: https://issues.apache.org/jira/browse/FLINK-29577
             Project: Flink
          Issue Type: Improvement
          Components: Runtime / State Backends
            Reporter: Cai Liuyang


For now, RocksDBFullRestoreOperation and RocksDBHeapTimersFullRestoreOperation does's pass RocksDB::WriteOptions to RocksDBWriteBatchWrapper when restore kv-data, which will use RocksDBWriteBatchWrapper‘s default WriteOptions(doesn't disable rocksdb wal explicitly, see code below), so during restoring from full snapshot, wal is enabled(use more disk and affect rocksdb-write-performance when restoring)

 
{code:java}
// First: RocksDBHeapTimersFullRestoreOperation::restoreKVStateData() doesn't pass WriteOptions to RocksDBWriteBatchWrapper(null as default)

private void restoreKVStateData(
        ThrowingIterator<KeyGroup> keyGroups,
        Map<Integer, ColumnFamilyHandle> columnFamilies,
        Map<Integer, HeapPriorityQueueSnapshotRestoreWrapper<?>> restoredPQStates)
        throws IOException, RocksDBException, StateMigrationException {
    // for all key-groups in the current state handle...
    try (RocksDBWriteBatchWrapper writeBatchWrapper =
            new RocksDBWriteBatchWrapper(this.rocksHandle.getDb(), writeBatchSize)) {
        HeapPriorityQueueSnapshotRestoreWrapper<HeapPriorityQueueElement> restoredPQ = null;
        ColumnFamilyHandle handle = null;
   ......
}


// Second: RocksDBWriteBatchWrapper::flush function doesn't disable wal explicitly when user doesn't pass WriteOptions to RocksDBWriteBatchWrapper
public void flush() throws RocksDBException {
    if (options != null) {
        db.write(options, batch);
    } else {
        // use the default WriteOptions, if wasn't provided.
        try (WriteOptions writeOptions = new WriteOptions()) {
            db.write(writeOptions, batch);
        }
    }
    batch.clear();
}

{code}
 

 

As we known, rocksdb's wal is usesless for flink, so i think we can disable wal for RocksDBWriteBatchWrapper's default WriteOptions.



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