Re: High CPU after read timeout

[Chris Lohfink]

There is no mechanism for reads to timeout once they have started. The
messaging service will drop the request when its received on the ReadStage
or RequestResponseStage. This is how its always operated so not unique to
3.9. If a client disconnects from a coordinator there is also no way for
the replicas who received a read request from the coordinator to know that
the client was disconnected.

Would be an interesting JIRA but as a note, it will likely not be a quick
fix. Theres internal mechanisms that don't really have a concept of a
timeout and where we would want it to never timeout (ie a compaction,
reading system tables to fill meta data, repairs etc) and currently theres
no way of differentiating between them.

Chris

On Thu, Jul 13, 2017 at 10:53 PM, Vladimir Yudovin 
wrote:

> Hi,
>
>
>
> Cassandra 3.9, I found after some ALLOW FILTERING request running on huge
> partition fails with Cassandra timeout during read query at consistency ONE
> (1 responses were required but only 0 replica responded) nodes continue to
> consume CPU in ReadStage-N threads, as if they still performing search
> despite failed request and even disconnected client.
>
>
>
>  Is it something known or probably it's worth JIRA filling?
>
>
>
>
>
> Best regards, Vladimir Yudovin,
>
> Winguzone - Cloud Cassandra Hosting
>
>
>
>
>
>

High CPU after read timeout

[Vladimir Yudovin]

Hi,



Cassandra 3.9, I found after some ALLOW FILTERING request running on huge 
partition fails with Cassandra timeout during read query at consistency ONE (1 
responses were required but only 0 replica responded) nodes continue to consume 
CPU in ReadStage-N threads, as if they still performing search despite failed 
request and even disconnected client.



 Is it something known or probably it's worth JIRA filling?





Best regards, Vladimir Yudovin, 

Winguzone - Cloud Cassandra Hosting

Re: possible race in copy from csv, cassandra 3.9

[Stefania Alborghetti]

Looks similar to what was fixed by CASSANDRA-12740
, released in 3.10.

On Thu, Jul 13, 2017 at 5:43 PM, Micha  wrote:

> I use "copy from" to import a bunch of csv files, each with 100 rows
> (exported by "copy to" from another table)
>
> There is a chance that the copy from just hangs, after importing 9995000
> lines, doing nothing, waiting forever.
>
> Could this be a race in the copy code? I use NUMPROCESSES=6, in bash a
> "ps" shows 8 started cqlsh.py processes. For me it seems that all of the
> processes are waiting for the signal that the import is done, but they
> are all blocked. So they wait forever.
>
> Checking random records of the imported file indicate that it is
> completely imported.
>
> The logs show no errors.
>
> Any suggestions?
>
> Thanks,
>  Michael
>
>
>
>
>
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>


-- 



STEFANIA ALBORGHETTI

Software engineer | +852 6114 9265 | stefania.alborghe...@datastax.com


[image: http://www.datastax.com/cloud-applications]

possible race in copy from csv, cassandra 3.9

[Micha]

I use "copy from" to import a bunch of csv files, each with 100 rows
(exported by "copy to" from another table)

There is a chance that the copy from just hangs, after importing 9995000
lines, doing nothing, waiting forever.

Could this be a race in the copy code? I use NUMPROCESSES=6, in bash a
"ps" shows 8 started cqlsh.py processes. For me it seems that all of the
processes are waiting for the signal that the import is done, but they
are all blocked. So they wait forever.

Checking random records of the imported file indicate that it is
completely imported.

The logs show no errors.

Any suggestions?

Thanks,
 Michael





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