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From Varun Thacker <va...@vthacker.in>
Subject Re: Limiting the number of queries/updates to Solr
Date Fri, 04 Aug 2017 22:30:34 GMT
Hi Hrishikesh,

I think SOLR-7344 is probably an important addition to Solr. It could help
users isolate analytical queries ( streaming ) , search queries and
indexing requests and throttle requests

Let's continue the discussion on the Jira

On Thu, Aug 3, 2017 at 2:03 AM, Rick Leir <rleir@leirtech.com> wrote:

>
>
> On 2017-08-02 11:33 PM, Shawn Heisey wrote:
>
>> On 8/2/2017 8:41 PM, S G wrote:
>>
>>> Problem is that peak load estimates are just estimates.
>>> It would be nice to enforce them from Solr side such that if a rate
>>> higher than that is seen at any core, the core will automatically begin to
>>> reject the requests.
>>> Such a feature would contribute to cluster stability while making sure
>>> the customer gets an exception to remind them of a slower rate.
>>>
>> Solr doesn't have anything like this.  This is primarily because there
>> is no network server code in Solr.  The networking is provided by the
>> servlet container.  The container in modern Solr versions is nearly
>> guaranteed to be Jetty.  As long as I have been using Solr, it has
>> shipped with a Jetty container.
>>
>> https://wiki.apache.org/solr/WhyNoWar
>>
>> I have no idea whether Jetty is capable of the kind of rate limiting
>> you're after.  If it is, it would be up to you to figure out the
>> configuration.
>>
>> You could always put a proxy server like haproxy in front of Solr.  I'm
>> pretty sure that haproxy is capable rejecting connections when the
>> request rate gets too high.  Other proxy servers (nginx, apache, F5
>> BigIP, solutions from Microsoft, Cisco, etc) are probably also capable
>> of this.
>>
>> IMHO, intentionally causing connections to fail when a limit is exceeded
>> would not be a very good idea.  When the rate gets too high, the first
>> thing that happens is all the requests slow down.  The slowdown could be
>> dramatic.  As the rate continues to increase, some of the requests
>> probably would begin to fail.
>>
>> What you're proposing would be guaranteed to cause requests to fail.
>> Failing requests are even more likely than slow requests to result in
>> users finding a new source for whatever service they are getting from
>> your organization.
>>
> Shawn,
> Agreed, a connection limit is not a good idea.  But there is the
> timeAllowed parameter <https://cwiki.apache.org/conf
> luence/display/solr/Common+Query+Parameters#CommonQueryPa
> rameters-ThetimeAllowedParameter>
> timeAllowed - This parameter specifies the amount of time, in
> milliseconds, allowed for a search to complete. If this time expires before
> the search is complete, any partial results will be returned.
>
> https://stackoverflow.com/questions/19557476/timing-out-a-query-in-solr
>
> With timeAllowed, you need not estimate what connection rate is
> unbearable. Rather, you would set a max response time. If some queries take
> much longer than other queries, then this would cause the long ones to
> fail, which might be a good strategy. However, if queries normally all take
> about the same time, then this would cause all queries to return partial
> results until the server recovers, which might be a bad strategy. In this
> case, Walter's post is sensible.
>
> A previous thread suggested that timeAllowed could cause bad performance
> on some cloud servers.
> cheers -- Rick
>
>
>
>
>

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