[Gluster-devel] gluster source code help

[jayakrishnan mm]

On Fri, Feb 3, 2017 at 7:58 PM, Ravishankar N <ravishankar at redhat.com>
wrote:

> On 02/03/2017 09:14 AM, jayakrishnan mm wrote:
>
>
>
> On Thu, Feb 2, 2017 at 8:17 PM, Ravishankar N <ravishankar at redhat.com>
> wrote:
>
>> On 02/02/2017 10:46 AM, jayakrishnan mm wrote:
>>
>> Hi
>>
>> How  do I determine, which part of the  code is run on the client, and
>> which part of the code is run on the server nodes by merely looking at the
>> the glusterfs  source code ?
>> I knew  there are client side  and server side translators which will run
>> on respective platforms. I am looking at part of self heal daemon source
>>  (ec/afr) which will run on the server nodes  and  the part which run on
>> the clients.
>>
>>
>> The self-heal daemon that runs on the server is also a client process in
>> the sense that it has client side xlators like ec or afr and
>> protocol/client (see the shd volfile 'glustershd-server.vol') loaded and
>> talks to the bricks like a normal client does.
>> The difference is that only self-heal related 'logic' get executed on the
>> shd while both self-heal and I/O related logic get executed from the mount.
>> The self-heal logic resides mostly in afr-self-heal*.[ch] while I/O related
>> logic is there in the other files.
>> HTH,
>> Ravi
>>
>
> Hi JK,
>
> Dear  Ravi,
> Thanks for your kind explanation.
> So, each server node will have a separate self-heal daemon(shd) up and
> running , every time a child_up event occurs, and this will  be an index
> healer.
> And each daemon  will spawn  "priv->child_count " number of threads on
> each server node . correct ?
>
> shd is always running and yes those many threads are spawned for index
> heal when the process starts.
>
> 1. When exactly a full healer spawns  threads?
>
> Whenever you run `gluster volume heal volname full`. See afr_xl_op().
> There are some bugs in launching full heal though.
>
> 2. When can GF_EVENT_TRANSLATOR_OP & GF_SHD_OP_HEAL_INDEX happen together
> (so that index healer spawns thread) ?
>     similarly when can GF_EVENT_TRANSLATOR_OP & GF_SHD_OP_HEAL_FULL
>  happen ? During replace-brick ?
> Is it possible that index healer and full healer spawns threads together
> (so that total number of  threads  is 2*priv->child_count)?
>
> index heal threads wake up and run once every 10 minutes or whatever the
> cluster.heal-timeout is. They are also run when a brick comes up like you
> said, via afr_notify(). It is also run when you manually launch 'gluster
> volume heal volname`. Again see afr_xl_op().
>
> 3. In /var/lib/glusterd/glustershd/glustershd-server.vol , why
>  debug/io-stats  is chosen as the top xlator ?
>
> io-stats is generally loaded as the top most xlator in all graphs at the
> appropriate place for gathering profile-info, but for shd, I'm not sure if
> it has any specific use other than acting as a placeholder as a parent to
> all replica xlators.
>

Thanks Ravi, for the explanation.
Regards
JK

>
> Regards,
> Ravi
>
> Thanks
> Best regards
>
>>
>> Best regards
>> JK
>>
>>
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>>
>>
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