# Causes for RocksDB Stall
+ Stall is the flow control mechanism of RocksDB.
+ Search for “Stalling” in the RocksDB log to find out causes for RocksDB stall.
  + The path for the RocksDB log: data/db/LOG
+ Causes and solutions for stall:
  + Too many level0 files exist
    + Set max-sub-compaction = 2 to speed up compacting level0 files to the lower level.
    + Set level0-slowdown-writes-trigger and level0-stop-writes-trigger to a larger value to relieve the peak pressure on the application. 
  + Too many memtables exist
    + If this is not the usual case, you can set max-write-buffer-number to relieve the peak pressure on the application.
  + The total volume of data for compaction is too large
    + Set [rocksdb.defaultcf] soft-pending-compaction-bytes-limit = “128GB” (64 GB by default) 
    + Is the write latency high or the disk under heavy write workload? Try TitanDB.
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