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Re: threads in cleaning up mode




Can it be  a consequence of slow disk also?

Best Regards,
Geetanjali Mehra
Senior Database Administrator


On Tue, Apr 5, 2016 at 10:50 AM, geetanjali mehra <
mailtogeetanjali@xxxxxxxxx> wrote:

> 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
>>
>> Become certified in MySQL! Visit https://www.mysql.com/certification/
>> for details.
>>
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>>
>