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From Erick Erickson <erickerick...@gmail.com>
Subject Re: Solr cloud questions
Date Thu, 15 Aug 2019 17:11:15 GMT
OK, if you’re sending HTTP requests to a single node, that’s
something of an anti-pattern unless it’s a load balancer that
sends request to random nodes in the cluster. Do note that
even if you do send all http requests to one node, the top-level
request will be forwarded to other nodes in the cluster.

But if your single node dies, then indeed there’s no way for Solr
to get the request in the other nodes.

If you use SolrJ, in particular CloudSolrClient, it’s ZooKeeper-aware
and will both avoid dead nodes _and_ distribute the top-level
queries to all the Solr nodes. It’ll also be informed when a dead
nodes comes back and put it back into the rotation.

Best,
Erick

> On Aug 15, 2019, at 10:14 AM, Kojo <rbsnkjmr@gmail.com> wrote:
> 
> Erick,
> I am starting to think that my setup has more than one problem.
> As I said before, I am not balancing my load to Solr nodes, and I have
> eight nodes. All of my web application requests go to one Solr node, the
> only one that dies. If I distribute the load across the other nodes, is it
> possible that these problems may end?
> 
> Even if I downsize the Solr cloud setup to 2 boxes 2 nodes each with less
> shards than the 16 shards that I have now, I would like to know your
> oppinion about the question above.
> 
> Thank you,
> Koji
> 
> 
> 
> 
> Em qua, 14 de ago de 2019 às 14:15, Erick Erickson <erickerickson@gmail.com>
> escreveu:
> 
>> Kojo:
>> 
>> On the surface, this is a reasonable configuration. Note that you may
>> still want to decrease the Java heap, but only if you have enough “head
>> room” for memory spikes.
>> 
>> How do you know if you have “head room”? Unfortunately the only good
>> answer is “you have to test”. You can look at the GC logs to see what your
>> maximum heap requirements are, then add “some extra”.
>> 
>> Note that there’s a balance here. Let’s say you can run successfully with
>> X heap, so you allocate X + 0.1X to the heap. You can wind up spending a
>> large amount of time in garbage collection. I.e. GC kicks in and recovers
>> _just_ enough memory to continue for a very short while, then goes into
>> another GC cycle. You don’t hit OOMs, but your system is slow.
>> 
>> OTOH, let’s say you need X and allocate 3X. Garbage will accumulate and
>> full GCs are rarer, but when they occur they take longer.
>> 
>> And the G1GC collector is the current preference
>> 
>> As I said, testing is really the only way to determine what the magic
>> number is.
>> 
>> Best,
>> Erick
>> 
>>> On Aug 14, 2019, at 9:20 AM, Kojo <rbsnkjmr@gmail.com> wrote:
>>> 
>>> Shawn,
>>> 
>>> Only my web application access this solr. at a first look at http server
>>> logs I didnt find something different.  Sometimes I have a very big
>> crawler
>>> access to my servers, this was my first bet.
>>> 
>>> No scheduled crons running at this time too.
>>> 
>>> I think that I will reconfigure my boxes with two solr nodes each instead
>>> of four and increase heap to 16GB. This box only run Solr and has 64Gb.
>>> Each Solr will use 16Gb and the box will still have 32Gb for the OS. What
>>> do you think?
>>> 
>>> This is a production server, so I will plan to migrate.
>>> 
>>> Regards,
>>> Koji
>>> 
>>> 
>>> Em ter, 13 de ago de 2019 às 12:58, Shawn Heisey <apache@elyograg.org>
>>> escreveu:
>>> 
>>>> On 8/13/2019 9:28 AM, Kojo wrote:
>>>>> Here are the last two gc logs:
>>>>> 
>>>>> 
>>>> 
>> https://send.firefox.com/download/6cc902670aa6f7dd/#Ee568G9vUtyK5zr-nAJoMQ
>>>> 
>>>> Thank you for that.
>>>> 
>>>> Analyzing the 20MB gc log actually looks like a pretty healthy system.
>>>> That log covers 58 hours of runtime, and everything looks very good to
>> me.
>>>> 
>>>> https://www.dropbox.com/s/yu1pyve1bu9maun/gc-analysis-kojo.png?dl=0
>>>> 
>>>> But the small log shows a different story.  That log only covers a
>>>> little more than four minutes.
>>>> 
>>>> https://www.dropbox.com/s/vkxfoihh12brbnr/gc-analysis-kojo2.png?dl=0
>>>> 
>>>> What happened at approximately 10:55:15 PM on the day that the smaller
>>>> log was produced?  Whatever happened caused Solr's heap usage to
>>>> skyrocket and require more than 6GB.
>>>> 
>>>> Thanks,
>>>> Shawn
>>>> 
>> 
>> 


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