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Re: threads in cleaning up mode




Thanks to everyone for response.  Any other views from any one is always
welcome.

Best Regards,
Geetanjali Mehra
Senior Database Administrator


On Mon, Apr 4, 2016 at 7:51 PM, shawn l.green <shawn.l.green@xxxxxxxxxx>
wrote:

>
>
> On 4/2/2016 10:36 AM, geetanjali mehra wrote:
>
>> Hi to all,
>>
>> For many days, I am struggling with the problem of  increasing history
>> list
>> length on mysql 5.6.29. Application that this server is running IOT based.
>> Also, this server has so many threads running in sleeping mode. SHOW
>> ENGINE
>> INNODB STATUS shows all these threads in *cleaning up* mode.
>> I tried all the options to reduce history list length. But it is
>> constantly
>> increasing.
>> Below are the current settings of purge related threads:
>>
>> innodb_max_purge_lag       | 1000000 |
>> | innodb_max_purge_lag_delay | 0       |
>> | innodb_purge_batch_size    | 1       |
>> | innodb_purge_threads       | 8       |
>>
>> Also, please let me know that whether cleaning up mode of threads and
>> history list length are correlated.
>>
>> Anty help?
>>
>>
>> Best Regards,
>> Geetanjali Mehra
>> Senior Database Administrator
>>
>>
> No, the "cleaning up" status and your ever-increasing history are not
> related. The "cleaning up" status is a very low-impact bug in our code. We
> simply forgot to reset a flag at the end of that section of the code. It is
> not indicative of any ongoing operations.
>
> What has happened is one of those idle threads (the sleeping ones) has
> opened a transaction but never committed it. That is why your history list
> is never shrinking.  As was already said in another response, this is an
> indication of poor client-side transaction management. If you start a
> transaction, you must always terminate it or situations like yours will
> happen. (This is also one of the dangers if someone changes autocommit=0
> and forgets to change it back.)
>
>
> --
> Shawn Green
> MySQL Senior Principal Technical Support Engineer
> Oracle USA, Inc. - Integrated Cloud Applications & Platform Services
> Office: Blountville, TN
>
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