Hi Alain,

when  "MemtableReclaimMemory"  Pending Tasks increasing, its slowly backing up reads and writes mostly writes. yes i am seeing bit high GC pressure, currently we are using 24Gb Heap  and G1GC collection. I tried changing Memtable flush threshold it did helped a little but not much. I am not seeing any Errors in the Logs.


On Thu, Apr 27, 2017 at 6:08 AM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:
Hi Pranay,

According to http://docs.datastax.com/en/cassandra/3.0/cassandra/tools/toolsTPstats.html, "MemtableReclaimMemory" is the thread pool used for "Making unused memory available". I don't know much about it since it was never an issue for me. Neither did I heard much about it.

  • Are pending tasks staying high for a long period? `watch -d nodetool tpstats`
  • What are your GC settings?
  • Any other threads pending, blocked or dropped?
  • Do you have errors or warnings in your logs?
  • Any GC pressure? (monitored through charts or logs at INFO level, or WARN on recent versions)

Alain Rodriguez - @arodream - alain@thelastpickle.com

The Last Pickle - Apache Cassandra Consulting

2017-04-16 16:04 GMT+02:00 Pranay akula <pranay.akula2323@gmail.com>:

what is MemtableReclaimMemory mean in nodetooltpstats ?? does this mean trying to flushing memtable from memory to SStables.

I can see sometimes increase in pending tasks of  MemtableReclaimMemory in nodetool tpstats, at that time i can see increase in load on those nodes.

Does decreasing memtable_cleanup_threshold will help ??