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From Francesco Zamboni <f.zamb...@mastertek.it>
Subject Re: problems with replication
Date Fri, 02 Oct 2015 17:16:53 GMT
I did some tests... with "test" recordset I reproduced consistently the
behaviour, creating huge single objects and then trying to index even a
single view.

The result is usually a long list of
[error] [<0.25586.2>] OS Process Error <0.28141.2> :: {os_process_error,
                                                       "OS process timed
out."}
Followed by a
[info] [<0.17278.2>] 127.0.0.1 - - GET /test/_design/docs/_view/list_1 500
[error] [emulator] Error in process <0.25586.2> with exit value:
{{nocatch,{os_process_error,"OS process timed
out."}},[{couch_os_process,prompt,2,[{file,"couch_os_process.erl"},{line,57}]},{couch_query_servers,map_doc_raw,2,[{file,"couch_query_servers.erl"},{line,88}]},{couch_mrview_updater...


With the "real" db it does remains not deterministic: sometimes it does
runs easily and quickly, sometimes it does lock completely, doing exactly
the same operations over exactly the same data.

Some of our records are in fact not small, but if attachments do not count,
they're also not really so big, having to ... the biggest are around
100-200k.

We had also some hang-ups while creating new filters, but those too seems
not deterministic: you run it, couchdb freezes and never recovers, then you
drop everything and re-create everything exactly the same and it does run
smoothly...
I'm trying to obtain some more informations from a "real db" crash, but the
fact that it does happens so randomly and with an application that, being
actively used, need to be restored ASAP, is frustrating my attempts,

One thing we've excluded is the machine/installation: we've moved the
database over different machines, with different network configurations,
and the behaviour do re-appear.

We're using couchdb 1.6.1 as a klaemo docker image over ubuntu 14.04 VMs,
but we tried even a physical machine with a packaged installation from
scratch.

I'll write again if (hopefully when!) I'll find more... in the meantime
thanks to everybody!

2015-09-29 22:36 GMT+02:00 Sebastian Rothbucher <
sebastianrothbucher@googlemail.com>:

> Hi Francesco,
>
> maybe these two things will help you:
> 1.) as Harald Pointed out: filtered replication could be a problem. An
> initial thought: make sure only one runs at a time. Surely not the solution
> in the long run, but could help figuring out where the problem is
> 2.) Try intercepting the couchjs process to find out more. Maybe it's
> always the same (typically huge) document where it hangs (see e.g. here:
> https://gist.github.com/sebastianrothbucher/01afe929095a55ab233e).
> Generally, looking for huge documents (huge content, attachments don't
> count here) might be worthwhile. When you exclude / delete these
> temporarily, it might be another lead. Again: not the final soltuion, but
> helps pointing it down
>
> Good luck, pls. share what you found - and also let us all know when we
> might be able to help
>
> Best
>    Sebastian
>
> On Tue, Sep 29, 2015 at 10:59 AM, Francesco Zamboni <
> f.zamboni@mastertek.it>
> wrote:
>
> > Hello,
> > we're having some problems with replication and couchdb, but as we're
> still
> > quite green with couchdb I need to ask to people with more experience
> even
> > what I can check, as the problem seems to be quite random and we've been
> > not capable to even pinpoint a way to consistently reproduce the problem.
> >
> > Essentially, using couchdb 1.6.1, we've uploaded some thousands of
> > documents occupying about 10 megabytes of space, more or less, so nothing
> > especially big...
> > Over these documents we've created a structure of views, lists, shows and
> > other functions.
> > The problems seems to start when we try to launch a series of one-shot
> > filtered replication of these data over several sub-databases.
> > After creating a variable number of replication documents, the system
> seems
> > to completely hang.
> > When the system is hanged, any attempt to access a view cause a crash.
> > The only messages are of the "OS process timed out" kind, but we've tried
> > to increase the os_process_timeout and os_process_limit parameters
> without
> > any appreciable change.
> >
> > Obviously this is not enough information to ask where the problem is, but
> > as we're new to couchdb, I'd like to ask for some pointers in what to
> > check, some common pitfalls that could lead to this kind of problems and
> so
> > on... we're having serious troubles understanding what happened when
> > something go wrong...
> >
> >
> >
> > --
> > Francesco Zamboni
> >
> > tel: +39 0522 1590100
> > fax: +39 0522 331673
> > mob: +39 335 7548422
> > e-mail: f.zamboni@mastertraining.it <g.muzzini@mastertraining.it>
> > web: www.mastertraining.it
> >
> >
> >  Sede Legale: via Timolini, 18 - Correggio (RE) - Italy
> > Sede Operativa: via Sani, 15 - Reggio Emilia - Italy
> > Sede Commerciale: via Sani, 9 - Reggio Emilia - Italy
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> > Qualora questo messaggio fosse da Voi ricevuto per errore vogliate
> > cortesemente darcene notizia a mezzo e-mail e distruggere il messaggio
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> > us immediately by telephone or fax.
> >
>



-- 
Francesco Zamboni

tel: +39 0522 1590100
fax: +39 0522 331673
mob: +39 335 7548422
e-mail: f.zamboni@mastertraining.it <g.muzzini@mastertraining.it>
web: www.mastertraining.it


 Sede Legale: via Timolini, 18 - Correggio (RE) - Italy
Sede Operativa: via Sani, 15 - Reggio Emilia - Italy
Sede Commerciale: via Sani, 9 - Reggio Emilia - Italy
Le informazioni contenute in questa e-mail sono da considerarsi
confidenziali e esclusivamente per uso personale dei destinatari sopra
indicati. Questo messaggio può includere dati personali o sensibili.
Qualora questo messaggio fosse da Voi ricevuto per errore vogliate
cortesemente darcene notizia a mezzo e-mail e distruggere il messaggio
ricevuto erroneamente. Quanto precede ai fini del rispetto del Decreto
Legislativo 196/2003 sulla tutela dei dati personali e sensibili.
This e-mail and any file transmitted with it is intended only for the
person or entity to which is addressed and may contain information
that is privileged, confidential or otherwise protected from
disclosure.Copying, dissemination or use of this e-mail or the
information herein by anyone other than the intended recipient is
prohibited. If you have received this e-mail by mistake, please notify
us immediately by telephone or fax.

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