Question though, how many tables do you have? If you have more than a few hundreds it could be bottlenecking the flushing if it is flushing very frequently.
On Mon, May 1, 2017 at 9:32 PM, Chris Lohfink <clohfin...@gmail.com> wrote: > Theres a read barrier to stop reclaiming a memtable when there are > requests actively reading it. The *MemtableReclaimMemory* pool offloads > that wait instead of blocking the caller. It in itself is not going to use > any cpu or increase load. It will however block the releasing of the > memtable resources which might cause additional heap allocation pressure. > Its more likely a symptom of GCs or reads being slow than the cause of the > issue however. > > Chris > > On Mon, May 1, 2017 at 9:01 PM, Pranay akula <pranay.akula2...@gmail.com> > wrote: > >> 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. >> >> >> Thanks >> Pranay. >> >> On Thu, Apr 27, 2017 at 6:08 AM, Alain RODRIGUEZ <arodr...@gmail.com> >> wrote: >> >>> Hi Pranay, >>> >>> According to http://docs.datastax.com/en/ca >>> ssandra/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) >>> >>> >>> C*heers, >>> ----------------------- >>> Alain Rodriguez - @arodream - al...@thelastpickle.com >>> France >>> >>> The Last Pickle - Apache Cassandra Consulting >>> http://www.thelastpickle.com >>> >>> >>> >>> 2017-04-16 16:04 GMT+02:00 Pranay akula <pranay.akula2...@gmail.com>: >>> >>>> Hi, >>>> >>>> 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 ?? >>>> >>>> Thanks >>>> Pranay. >>>> >>> >>> >> >
