[Gluster-devel] Question about EC locking

[jayakrishnan mm]

Hi Xavier,

Thank you very much for your explanation. This helped  me to understand
more  about  locking in EC.

Best Regards
JK


On Mon, Nov 28, 2016 at 4:17 PM, Xavier Hernandez <xhernandez at datalab.es>
wrote:

> Hi,
>
> On 11/28/2016 02:59 AM, jayakrishnan mm wrote:
>
>> Hi Xavier,
>>
>> Notice  that EC xlator uses blocking locks. Any specific reason for this?
>>
>
> In a distributed filesystem like gluster a synchronization mechanism is a
> must to avoid data corruption.
>
>
>> Do you think this will  affect the  performance ?
>>
>
> Of course the need for locks has a performance impact, and we cannot avoid
> them to guarantee data integrity. However some optimizations have been
> applied, specially the eager locking which allows a lock to be reused
> without unlocking/locking again.
>
>
>> (In comparison AFR  first tries  non blocking locks  and if not
>> successful, tries blocking locks then)
>>
>
> EC also tries a non-blocking lock first.
>
>
>> Also, why two locks  are  needed  per FOP ? One for normal I/O and
>> another for self healing?
>>
>
> The only fop that currently needs two locks is 'rename', and only when
> source and destination directories are different. All other fops only take
> one lock at most.
>
> Best regards,
>
> Xavi
>
>
>> Best regards
>> JK
>>
>>
>> _______________________________________________
>> Gluster-devel mailing list
>> Gluster-devel at gluster.org
>> http://www.gluster.org/mailman/listinfo/gluster-devel
>>
>>
>
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