Drop space and the folder was removed but the disk space was not released

[pengweisong]

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Describe the bug (required)

https://discuss.nebula-graph.com.cn/t/topic/11776/5
When the space was dropped, the space directory was removed successfully, but the spaces used by sst was not released successfully.

Your Environments (required)

• OS: uname -a
• Compiler: g++ --version or clang++ --version
• CPU: lscpu
• Commit id (e.g. a3ffc7d8) 3.2

How To Reproduce(required)

Steps to reproduce the behavior:

The reason has not been located, guess it may have sth to do with the compaction:

1. insert lot of data
2. submit a compact job
3. drop the space

Expected behavior

The space is released successfully.

Additional context

[HarrisChu]

interesting..
do we rocksdb::CancelAllBackgroundWork when we remove the space?

[pengweisong]

interesting.. do we rocksdb::CancelAllBackgroundWork when we remove the space?

RocksEngine::stop() has called it, but we did not call stop when drop space.. I'll add it.

What's more, we may should call rocksdb::Close() when deconstruct the RocksEngine.

[HarrisChu]

could not reproduce

[Sophie-Xie]

Close it first, reopen if it reappears.