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

["Hangxiang Yu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-29577?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hangxiang Yu reassigned FLINK-29577:
------------------------------------

    Assignee: Cai Liuyang

> 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
>            Assignee: Cai Liuyang
>            Priority: Major
>              Labels: pull-request-available
>
> 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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