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Posted to user@flink.apache.org by Kien Truong <du...@gmail.com> on 2017/08/02 08:24:07 UTC

Constant write stall warning with RocksDB state backend

Hi, 

With the setting SPINNING_DISK_OPTIMIZED_HIGH_MEM, I'm having a lot of warning from RocksDB:

Stalling writes because we have 3 immutable memtables (waiting for flush), max_write_buffer_number is set to 4 rate 16777216

Increasing max_write_buffer_number causes the message to go away, but I want to ask if there are any downside to it? 

Best regards, 
Kien Truong

Re: Constant write stall warning with RocksDB state backend

Posted by Stefan Richter <s....@data-artisans.com>.

Hi,

there is some documentation on this topic here https://github.com/facebook/rocksdb/wiki/Write-Stalls <https://github.com/facebook/rocksdb/wiki/Write-Stalls>. Increasing the buffer size seems ok, and the downside is a potentially higher memory footprint.

Best,
Stefan

> Am 02.08.2017 um 10:24 schrieb Kien Truong <du...@gmail.com>:
> 
> Hi, 
> 
> With the setting SPINNING_DISK_OPTIMIZED_HIGH_MEM, I'm having a lot of warning from RocksDB:
> 
> Stalling writes because we have 3 immutable memtables (waiting for flush), max_write_buffer_number is set to 4 rate 16777216
> 
> Increasing max_write_buffer_number causes the message to go away, but I want to ask if there are any downside to it? 
> 
> Best regards, 
> Kien Truong