Hi I am not worried about page cache. I want to monitor memory pressure, I want to check that if heap+non heap usage goes above certain level then I can take certain action. But due to this page cache thing, I am not sure how to find actual memory usage( heap and off heap). Heap will not be more than 8G. Off heap increases with data on disk due to off heap storage of bloom filters and index files. I want to know the exact amount of memory occupied by off heap components. Nodetool info output does not look appropriate to me or I am missing something.
Regards Himanshu On Sat, Apr 11, 2020 at 10:13 PM Laxmikant Upadhyay <laxmikant....@gmail.com> wrote: > Hi, > > You can read section 'OS Page Cache Usage' on > http://cassandra.apache.org/doc/latest/troubleshooting/use_tools.html > Also, don't worry about memory usage (page cache) not decreasing even if > no traffic ...it will come down when required (for example: a new > application needs it when boot up). > > On Sat, Apr 11, 2020 at 5:29 PM HImanshu Sharma < > himanshusharma0...@gmail.com> wrote: > >> Hi >> >> I am observing memory usage in top command, but there in RSS it is >> showing 18G ( which I think is sum of used memo + page cache). I want to >> know how to find how much used by Cassandra process and how much of it is >> in page cache. I want this information because I want to check memory usage >> for monitoring. >> >> On Sat, Apr 11, 2020 at 9:42 PM Nitan Kainth <nitankai...@gmail.com> >> wrote: >> >>> You can look at top command. There is column of memory >>> >>> >>> Regards, >>> >>> Nitan >>> >>> Cell: 510 449 9629 >>> >>> On Apr 11, 2020, at 11:10 AM, HImanshu Sharma < >>> himanshusharma0...@gmail.com> wrote: >>> >>> >>> Hi >>> >>> But I see memory not decreasing even if there is no traffic on cluster. >>> How can I find actual memory usage by Cassandra process. If it is OS page >>> cache then how to find how much is page cache and how much is used by >>> process? >>> >>> Thanks >>> Himanshu >>> >>> On Sat, Apr 11, 2020 at 9:07 PM Laxmikant Upadhyay < >>> laxmikant....@gmail.com> wrote: >>> >>>> It is OS page cache used during read..your os will leverage memory if >>>> not being used by any other applications and it improves your read >>>> performance. >>>> >>>> On Sat, Apr 11, 2020, 12:47 PM HImanshu Sharma < >>>> himanshusharma0...@gmail.com> wrote: >>>> >>>>> Hi >>>>> >>>>> I am very new to the use of cassandra. In a cassandra cluster of 3 >>>>> nodes, I am observing memory usage of cassandra process going more than >>>>> the >>>>> heap memor allocated. As I understand, cassandra allocates off heap memory >>>>> for bloom filters, index summary etc. >>>>> >>>>> When I run nodetool info, I see off heap memory usage around 1.5G, my >>>>> heap is 8G. So memory usage should not go above 10G. But in running node >>>>> it goes as high as 18G with heavy loads. It comes down with different >>>>> loads >>>>> but always more than 12G. >>>>> >>>>> I would like to know why memory usage is high and is there way to >>>>> control it. >>>>> >>>>> Thanks >>>>> Himanshu Sharma >>>>> >>>> > > -- > > regards, > Laxmikant Upadhyay > >
