[Gluster-devel] gluster source code help

[Ravishankar N]

On 02/06/2017 03:15 PM, jayakrishnan mm wrote:
>
>
> On Mon, Feb 6, 2017 at 2:36 PM, jayakrishnan mm 
> <jayakrishnan.mm at gmail.com <mailto:jayakrishnan.mm at gmail.com>> wrote:
>
>
>
>     On Fri, Feb 3, 2017 at 7:58 PM, Ravishankar N
>     <ravishankar at redhat.com <mailto: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 <mailto: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.
>
>
>
>
> Hi Ravi,
>
> The self heal daemon searches   in .glusterfs/indices/xattrop   
> directory for the files/dirs  to be healed . Who is updating this 
> information , and on what basis ?
>
>
Please see 
https://github.com/gluster/glusterfs-specs/blob/master/done/Features/afr-v1.md, 
it is a bit dated (relevant to AFR v1, which is in glusterfs 3.5 and 
older I think) but the concepts are similar. The entries are 
added/removed by the index translator during the pre-op/post-op phases 
of the AFR transaction .


>     Thanks Ravi, for the explanation.
>     Regards
>     JK
>
>
>         Regards,
>         Ravi
>>         Thanks
>>         Best regards
>>
>>>
>>>             Best regards
>>>             JK
>>>
>>>
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>>
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