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From Marcelo Elias Del Valle <marc...@s1mbi0se.com.br>
Subject Re: Batch of prepared statements exceeding specified threshold
Date Fri, 20 Jun 2014 18:02:43 GMT
If you have 32 Gb RAM, the heap is probably 8Gb.
200 writes of 100 kb / s would be 20MB / s in the worst case, supposing all
writes of a replica goes to a single node.
I really don't see any reason why it should be filling up the heap.
Anyone else?

But did you check the logs for the GCInspector?
In my case, nodes are falling because of the heap, in your case, maybe it's
something else.
Do you see increased times when looking for GCInspector in the logs?

[]s



2014-06-20 14:51 GMT-03:00 Pavel Kogan <pavel.kogan@cortica.com>:

> Hi Marcelo,
>
> No pending write tasks, I am writing a lot, about 100-200 writes each up
> to 100Kb every 15[s].
> It is running on decent cluster of 5 identical nodes, quad cores i7 with
> 32Gb RAM and 480Gb SSD.
>
> Regards,
>   Pavel
>
>
> On Fri, Jun 20, 2014 at 12:31 PM, Marcelo Elias Del Valle <
> marcelo@s1mbi0se.com.br> wrote:
>
>> Pavel,
>>
>> In my case, the heap was filling up faster than it was draining. I am
>> still looking for the cause of it, as I could drain really fast with SSD.
>>
>> However, in your case you could check (AFAIK) nodetool tpstats and see if
>> there are too many pending write tasks, for instance. Maybe you really are
>> writting more than the nodes are able to flush to disk.
>>
>> How many writes per second are you achieving?
>>
>> Also, I would look for GCInspector in the log:
>>
>> cat system.log* | grep GCInspector | wc -l
>> tail -1000 system.log | grep GCInspector
>>
>> Do you see it running a lot? Is it taking much more time to run each time
>> it runs?
>>
>> I am no Cassandra expert, but I would try these things first and post the
>> results here. Maybe other people in the list have more ideas.
>>
>> Best regards,
>> Marcelo.
>>
>>
>> 2014-06-20 8:50 GMT-03:00 Pavel Kogan <pavel.kogan@cortica.com>:
>>
>> The cluster is new, so no updates were done. Version 2.0.8.
>>> It happened when I did many writes (no reads). Writes are done in small
>>> batches of 2 inserts (writing to 2 column families). The values are big
>>> blobs (up to 100Kb).
>>>
>>> Any clues?
>>>
>>> Pavel
>>>
>>>
>>> On Thu, Jun 19, 2014 at 8:07 PM, Marcelo Elias Del Valle <
>>> marcelo@s1mbi0se.com.br> wrote:
>>>
>>>> Pavel,
>>>>
>>>> Out of curiosity, did it start to happen before some update? Which
>>>> version of Cassandra are you using?
>>>>
>>>> []s
>>>>
>>>>
>>>> 2014-06-19 16:10 GMT-03:00 Pavel Kogan <pavel.kogan@cortica.com>:
>>>>
>>>>> What a coincidence! Today happened in my cluster of 7 nodes as well.
>>>>>
>>>>> Regards,
>>>>>   Pavel
>>>>>
>>>>>
>>>>> On Wed, Jun 18, 2014 at 11:13 AM, Marcelo Elias Del Valle <
>>>>> marcelo@s1mbi0se.com.br> wrote:
>>>>>
>>>>>> I have a 10 node cluster with cassandra 2.0.8.
>>>>>>
>>>>>> I am taking this exceptions in the log when I run my code. What my
>>>>>> code does is just reading data from a CF and in some cases it writes
new
>>>>>> data.
>>>>>>
>>>>>>  WARN [Native-Transport-Requests:553] 2014-06-18 11:04:51,391
>>>>>> BatchStatement.java (line 228) Batch of prepared statements for
>>>>>> [identification1.entity, identification1.entity_lookup] is of size
6165,
>>>>>> exceeding specified threshold of 5120 by 1045.
>>>>>>  WARN [Native-Transport-Requests:583] 2014-06-18 11:05:01,152
>>>>>> BatchStatement.java (line 228) Batch of prepared statements for
>>>>>> [identification1.entity, identification1.entity_lookup] is of size
21266,
>>>>>> exceeding specified threshold of 5120 by 16146.
>>>>>>  WARN [Native-Transport-Requests:581] 2014-06-18 11:05:20,229
>>>>>> BatchStatement.java (line 228) Batch of prepared statements for
>>>>>> [identification1.entity, identification1.entity_lookup] is of size
22978,
>>>>>> exceeding specified threshold of 5120 by 17858.
>>>>>>  INFO [MemoryMeter:1] 2014-06-18 11:05:32,682 Memtable.java (line
>>>>>> 481) CFS(Keyspace='OpsCenter', ColumnFamily='rollups300') liveRatio
is
>>>>>> 14.249755859375 (just-counted was 9.85302734375).  calculation took
3ms for
>>>>>> 1024 cells
>>>>>>
>>>>>> After some time, one node of the cluster goes down. Then it goes
back
>>>>>> after some seconds and another node goes down. It keeps happening
and there
>>>>>> is always a node down in the cluster, when it goes back another one
falls.
>>>>>>
>>>>>> The only exceptions I see in the log is "connected reset by the
>>>>>> peer", which seems to be relative to gossip protocol, when a node
goes down.
>>>>>>
>>>>>> Any hint of what could I do to investigate this problem further?
>>>>>>
>>>>>> Best regards,
>>>>>> Marcelo Valle.
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>

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