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From Laxmikant Upadhyay <laxmikant....@gmail.com>
Subject Re: Memory usage more than heap memory
Date Sat, 11 Apr 2020 16:43:21 GMT
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 <
himanshusharma0038@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 <nitankainth@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 <
>> himanshusharma0038@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.hcl@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 <
>>> himanshusharma0038@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

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