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From: Pranay akula <pranay.akula2323@gmail.com>
Date: Mon, 1 May 2017 22:01:20 -0400
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Subject: Re: what is MemtableReclaimMemory mean ??
To: Alain RODRIGUEZ <arodrime@gmail.com>
Cc: user@cassandra.apache.org
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archived-at: Tue, 02 May 2017 02:01:27 -0000

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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 <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)
>
>
> C*heers,
> -----------------------
> Alain Rodriguez - @arodream - alain@thelastpickle.com
> France
>
> The Last Pickle - Apache Cassandra Consulting
> http://www.thelastpickle.com
>
>
>
> 2017-04-16 16:04 GMT+02:00 Pranay akula <pranay.akula2323@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.
>>
>
>

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<div dir=3D"ltr">Hi Alain,<div><br></div><div>when =C2=A0<span style=3D"fon=
t-size:12.8px">&quot;</span><b style=3D"font-size:12.8px">MemtableReclaimMe=
mory</b><span style=3D"font-size:12.8px">&quot; =C2=A0Pending Tasks increas=
ing, its slowly backing up reads and writes mostly writes. yes i am seeing =
bit high GC pressure, currently we are using 24Gb Heap =C2=A0and G1GC colle=
ction. I tried changing Memtable flush threshold it did helped a little but=
 not much. I am not seeing any Errors in the Logs.</span></div><div><span s=
tyle=3D"font-size:12.8px"><br></span></div><div><span style=3D"font-size:12=
.8px"><br></span></div><div><span style=3D"font-size:12.8px">Thanks</span><=
/div><div><span style=3D"font-size:12.8px">Pranay.</span></div><div class=
=3D"gmail_extra"><br><div class=3D"gmail_quote">On Thu, Apr 27, 2017 at 6:0=
8 AM, Alain RODRIGUEZ <span dir=3D"ltr">&lt;<a href=3D"mailto:arodrime@gmai=
l.com" target=3D"_blank">arodrime@gmail.com</a>&gt;</span> wrote:<br><block=
quote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc=
 solid;padding-left:1ex"><div dir=3D"ltr">Hi Pranay,<div><br></div><div>Acc=
ording to <a href=3D"http://docs.datastax.com/en/cassandra/3.0/cassandra/to=
ols/toolsTPstats.html" target=3D"_blank">http://docs.datastax.com/en/<wbr>c=
assandra/3.0/cassandra/tools/<wbr>toolsTPstats.html</a>, &quot;<b style=3D"=
font-size:12.8px">MemtableReclaimMemory</b><span style=3D"font-size:12.8px"=
>&quot; is the thread pool used for &quot;Making unused memory available&qu=
ot;. I don&#39;t know much about it since it was never an issue for me. Nei=
ther did I heard much about it.</span><br></div><div><span style=3D"font-si=
ze:12.8px"><br></span></div><div><ul><li>Are pending tasks staying high for=
 a long period? `watch -d nodetool tpstats`</li><li>What are your GC settin=
gs?</li><li>Any other threads pending, blocked or dropped?</li><li>Do you h=
ave errors or warnings in your logs?</li><li>Any GC pressure? (monitored th=
rough charts or logs at INFO level, or WARN on recent versions)</li></ul><d=
iv><br></div></div><div>C*heers,</div><div><div>-----------------------</di=
v><div>Alain Rodriguez - @arodream - <a href=3D"mailto:alain@thelastpickle.=
com" target=3D"_blank">alain@thelastpickle.com</a></div><div>France</div><d=
iv><br></div><div>The Last Pickle - Apache Cassandra Consulting</div><div><=
a href=3D"http://www.thelastpickle.com" target=3D"_blank">http://www.thelas=
tpickle.com</a></div></div><div><span style=3D"font-size:12.8px"><br></span=
></div><div><span style=3D"font-size:12.8px"><br></span></div></div><div cl=
ass=3D"HOEnZb"><div class=3D"h5"><div class=3D"gmail_extra"><br><div class=
=3D"gmail_quote">2017-04-16 16:04 GMT+02:00 Pranay akula <span dir=3D"ltr">=
&lt;<a href=3D"mailto:pranay.akula2323@gmail.com" target=3D"_blank">pranay.=
akula2323@gmail.com</a>&gt;</span>:<br><blockquote class=3D"gmail_quote" st=
yle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div =
dir=3D"ltr">Hi,<div><br></div><div>what is <b>MemtableReclaimMemory</b> mea=
n in nodetooltpstats ?? does this mean trying to flushing memtable from mem=
ory to SStables.<br><div><br></div><div>I can see sometimes increase in pen=
ding tasks of =C2=A0MemtableReclaimMemory in nodetool tpstats, at that time=
 i can see increase in load on those nodes.</div><div><br></div><div>Does d=
ecreasing=C2=A0memtable_cleanup_th<wbr>reshold will help ??</div><div><br><=
/div><div>Thanks</div><span class=3D"m_7769317837312263330HOEnZb"><font col=
or=3D"#888888"><div>Pranay.</div></font></span></div></div>
</blockquote></div><br></div>
</div></div></blockquote></div><br></div></div>

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