Server idle yet memcached.exe and erl.exe CPU use is extremly high

I am not a Couchbase Server user (don’t even know what that is), but I am using RabbitMQ in a project and RabitMQ uses Erlang.

This morning, when I arrived at work, I found erl.exe running at 25% of the CPU even though there has been absolutely no use been made of RabbitMQ for many days (possibly weeks) now.

Sounds like a Erlang bug.

@cihangirb,

It just started again.memcached.exe is >90% continuously.
I downgraded the node from Azure A2 to A1.

Where you able to learn anything from the dump I sent you by email ?

I followed your suggestion and gracefully failed it. It takes ages to fail a node with 100% CPU. When finished, erl.exe CPU usage was ~15%. memcached.exe practically disappeared.
Node recovered. This should not occur :tired_face:

What should I do the next time ?
What should I do so that there will not be a next time ?

Itay

Hi @Itay, Don’t have a fix for the issue. We need access to the box to do a little more digging. See dave’s note here: https://issues.couchbase.com/browse/MB-12775

Would you be able to give access to the box?
thanks
-cihan

The box is busy doing other stuff :smirk:

Was there a resolution to this issue? I’m facing the same thing on my Windows 2012 R2 Azure VM. The 2 processes, memcached and erl.exe. eat up 99% CPU with memcache spiking between 75% and 90% and erl.exe eating the remainder.

This was reported as https://issues.couchbase.com/browse/MB-14036, which is marked as fixed in 4.0.0. I believe 4.0.0 should be out in the near future.

Does 4.0.0 replaces 3.x.x ?
Or more specifically, should I upgrade from 3.0.1 CE to 4.0.0 or should I continue with the 3.x.x family ?

Hi @itay, 4.0 replaces 3.0 so you should upgrade when 4.0.0 is released. you will get improvements in performance by upgrading even if you are not using the new query language or indexing on the core data operations.
thanks
-cihan

Will 4.0.0 new release be Community Edition ?

yes RC0 that has been published this past monday already has the release candidate for community edition and enterprise edition - couchbase.com/downloads
-cihan

Just saw your answer.

I’m a bit afraid of using RC. Is it stable and bug free ?
3.0.1 CE is really giving me a bad time so I want to make sure that I’m making the right decisions, as upgrading the DB is a delicate operation.

Will the full 4.0.0 version be released CE as well ? Is there a time frame ?
Will 3.0.3 be CE soon ?
Is there a page where you publish your versions road map ?

Thanks,

Hi @itay, The timeline for 4.0 CE is early Oct. 4.0 includes all fixes in 3.0.3 version so I would recommend 4.0 CE when we are generally available. RC0 is not the finished version so we still have a few fixes we are adding before the targeted oct date.
thanks
-cihan

Excellent
Does 4.0 requires any code modifications or is it plug and pray ?

4.0 is fully backward compatible unless you are using an un-documented method or you don’t know about the items we have here in the deprecation list (below),
http://developer.couchbase.com/documentation/server/4.0/release-notes/deprecated.html

Thanks,
I’m using .NET SDK so I guess there will be a specific version for 4.0 that will notify on any deprecated feature by not implementing them

@cihangirb,

Before migrating from 3.0.1 CE to 4.0.0 CE, where can I find a guide, manual, walkthru on how to do it correctly and successfully for the first time, on a running cluster ?

Thanks, Itay

Hi @itay, pls rehearse on another cluster first to make sure things work well. Also review the known issues list to ensure there isn’t anything that would impact your specific case.

You can find the upgrade manual here.
There are 3 upgrade strategies listed on the page and all 3 strategies mentioned here will work with CE.
Thanks
-cihan

Thanks @cihangirb,

@jmorris, Should I upgrade from .NET SDK 2.1.3 to 2.2.1 before or after I upgrade to 4.0.0 CE ?

@itay -

I would move to 2.2.1 after you upgrade to 4.0.0 CE.

Thanks,

Jeff

Thanks,
I’ll first upgrade the cluster and then the SDK