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From Rick Dig <teram...@gmail.com>
Subject Re: SolrClould 6.6 stability challenges
Date Sun, 05 Nov 2017 17:12:42 GMT
hi Shawn, all,
answers inline.
also, another discovery, not sure if completely useful. even when we
increase the autocommit values to say an hour, the nodes go "down" in 10-15
minutes. so either we are doing something wrong with autocommit settings
and commits are continuing to happen frequently (how do we confirm that
this isn't the case?) or they don't seem to matter to our scenario.
but like i mentioned before, querying and indexing work completely fine
when the other thing isn't running.

also, roughly 60% of the queries are "autocomplete" on a N-gram multivalued
field, which uses payload parsing as well as highlighting.

thanks



>>
> My two cents to add to what you've already seen:
>
> With 300K documents and 400MB of index size, an 8GB heap seems very
> excessive, even with complex queries.  What evidence do you have that you
> need a heap that size?  Are you just following a best practice
> recommendation you saw somewhere to give half your memory to Java?
>
*no hard evidence per se but pretty much a best practice recommendation. we
were allocating half of the memory available on the machine to the heap.*


>
> This is a *tiny* index by both document count and size.  Each document
> cannot be very big.
>
> Your GC log doesn't show any issues that concern me.  There are a few slow
> GCs, but when you index, that's probably to be expected, especially with an
> 8GB heap.
>
> What exactly do you mean by "one of the follower nodes goes down"?  When
> this happens, are there error messages at the time of the event?  What
> symptoms are there pertaining to that specific node?
>
*When a "node" goes down - the jvm continues to run but zookeeper shows the
node as "down" and queries stop being routed to that node.*



>
> A query load of 2000 per minute is about 33 per second.  Are these queries
> steady for the full minute, or is it bursty?  33 qps is high, but not
> insane, and with such a tiny index, is probably well within Solr's
> capabilities.
>
*the query volumes vary but we have never seen them go beyond 2000 per
minute. bursts are possible but haven't seen any massive bursts.*


>
> There should be no reason to *ever* increase maxWarmingSearchers.  If you
> see the warning about this, the fix is to reduce your commit frequency, not
> increase the value.  Increasing the value can lead to memory and
> performance problems.  The fact that this value is even being discussed,
> and that the value has been changed on your setup, has me thinking that
> there may be more commits happening than the every-five-minute autocommit.
>
*this was just a trial and error change, which we have since reverted,
because we have been struggling to understand the root cause.*

>
> For automatic commits, I have some recommendations for everyone to start
> with, and then adjust if necessary:  autoCommit: maxTime of 60000,
> openSearcher false.  autoSoftCommit, maxTime of 120000.  Neither one should
> have maxDocs configured.
>
> It should take far less than 20 seconds to index a 500 document batch,
> especially when they are small enough for 300K of them to produce a 400MB
> index.  There are only a few problems I can imagine right now that could
> cause such slow indexing, having no real information to go on:  1) The
> analysis chains in your schema are exceptionally heavy and take a long time
> to run.  2) There is a performance issue happening that we have not yet
> figured out.  3) Your indexing request includes a commit, and the commit is
> happening very slowly.
> *my apologies, the 20 second time  for a batch is  kinda misleading
> because this includes time taken for the application logic in constructing
> the data. *




> Here is a log entry on one of my indexes showing 1000 documents being
> added in 777 milliseconds.  The index that this is happening on is about
> 40GB in size, with about 30 million documents.  I have redacted part of the
> uniqueKey values in this log, to hide the sources of our data:
>
> 2017-11-04 09:30:14.325 INFO  (qtp1394336709-42397) [   x:spark6live]
> o.a.s.u.p.LogUpdateProcessorFactory [spark6live]  webapp=/solr
> path=/update params={wt=javabin&version=2}{add=[REDACTEDsix557224
> (1583127266377859072), REDACTEDsix557228 (1583127266381004800),
> REDACTEDtwo979483 (1583127266381004801), REDACTEDtwo979488
> (1583127266382053376), REDACTEDtwo979490 (1583127266383101952),
> REDACTEDsix557260 (1583127266383101953), REDACTEDsix557242
> (1583127266384150528), REDACTEDsix557258 (1583127266385199104),
> REDACTEDsix557247 (1583127266385199105), REDACTEDsix557276
> (1583127266394636288), ... (1000 adds)]} 0 777
>
> The rate I'm getting here of 1000 docs in 777 milliseconds is a rate that
> I consider to be pretty slow, especially because my indexing is
> single-threaded.  But it works for us.  What you're seeing where 500
> documents takes 20 seconds is slower than I've EVER seen, except in
> situations where there's a serious problem.  On a system in good health,
> with multiple threads indexing, Solr should be able to index several
> thousand documents every second.
>
> Is the indexing program running on the same machine as Solr, or on another
> machine?  For best results, it should be on a different machine, accessing
> Solr via HTTP.  This is so that whatever load the indexing program creates
> does not take CPU, memory, and I/O resources away from Solr.
>
*the indexing programs run on a different machine and solr is accessed via
http.*


>
> What OS is Solr running on?  If more information is needed, it will be a
> good idea to know precisely how to gather that information.
>
*solr is running on Ubuntu*

>
> Overall, based on the information currently available, you should not be
> having the problems you are.  So there must be something about your setup
> that's not configured correctly beyond the information we've already got.
> It could be directly Solr-related, or something else indirectly causing
> problems.  I do not yet know exactly what information we might need to help.
>
> Can you share an entire solr.log file that covers enough time so that
> there is both indexing and querying happening?  If it also covers that node
> going down, that would be even better.  You'll probably need to use a
> file-sharing website to share the log -- I'm surprised your GC log made it
> to the list.
> *will get a log uploaded and share with the group.*



> Thanks,
> Shawn
>

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