[leo_object_storage] [leo_backend_db] LeoFS's LevelDB settings are hard-coded and conservative

[windkit]

Description

It seems compaction process in leveldb makes leo_storage unresponsive, probably caused the issue #503

Observation

leo_backend_db_eleveldb sets several parameters at eleveldb:open
(https://github.com/leo-project/leo_backend_db/blob/develop/src/leo_backend_db_eleveldb.erl#L58)

1. Write Buffer Size: 256KB ~ 3MB [random(?!)]
2. Max Open Files: 32
3. Cache Size: 64MB (Such Option Not Found)
4. Block Size: 10KB (Deprecated, sst_block_size Instead)

defaults for basho/leveldb
(https://github.com/basho/leveldb/blob/develop/util/options.cc#L28)

1. Write Buffer Size: 60MB
2. Max Open File: 1000
3. SST Block Size: 4KB

Testing

Load Image Set, (4.000,000 Files, ~32KB Average)

Results

leo_backend_db_eleveldb defaults

eleveldb (leveldb) defaults

[windkit]

Attempt to Fix, Pass Options with app configuration, Update defaults

leo-project/leo_backend_db#6
leo-project/leo_storage#21

Result

1. Old LeoFS Defaults (32 Max Open Files, 3MB Write Buffer)
2. New Defaults (1000 Max Open Files, 60MB Write Buffer)
   

[yosukehara]

DONE