[PATCH] Re: Solr connection timeout hardwired to 60s

[John Fawcett]

On 14/04/2019 16:04, Aki Tuomi via dovecot wrote:
>
>> On 14 April 2019 16:59 John Fawcett via dovecot < dovecot at dovecot.org
>> <mailto:dovecot at dovecot.org>> wrote:
>>
>>
>> On 13/04/2019 17:16, Shawn Heisey via dovecot wrote:
>>> On 4/13/2019 4:29 AM, John Fawcett via dovecot wrote:
>>>> If this value was made configurable people could set it to what they
>>>> want. However the underlying problem is likely on solr configuration.
>>> The Jetty that is included in Solr has its idle timeout set to 50
>>> seconds.  But in practice, I have not seen this timeout trigger ...
>>> and if the OP is seeing a 60 second timeout, then the 50 second idle
>>> timeout in Jetty must not be occurring.
>>> There may be a socket timeout configured on inter-server requests --
>>> distributed queries or the load balancing that SolrCloud does.  I can
>>> never remember whether this is the case by default.  I think it is.
>> >> If there is an issue on initial indexing, where you are not really
>> >> concerned about qucik visibility but just getting things into the
>> index
>> >> efficiently, a better approach would be for dovecot plugin not to
>> send
>> >> any commit or softCommit (or waitSearcher either) and that should
>> speed
>> >> things up. You'd need to configure solr with a long autoSoftCommit
>> >> maxTime and a reasonable autoCommit maxTime, which you could then
>> >> reconfigure when the load was done.
>> >
>>> Solr ships with autoCommit set to 15 seconds and openSearcher set to
>>> false on the autoCommit.  The autoSoftCommit setting is not enabled by
>>> default, but depending on how the index was created, Solr might try to
>>> set autoSoftCommit to 3 seconds ... which is WAY too short.
>>> I will usually increase the autoCommit time to 60 seconds, just to
>>> reduce the amount of work that Solr is doing.  The autoSoftCommit
>>> time, if it is used, should be set to a reasonably long value ...
>>> values between two and five minutes would be good.  Attempting to use
>>> a very short autoSoftCommit time will usually lead to problems.
>>> This thread says that dovecot is sending explicit commits.  One thing
>>> that might be happening to exceed 60 seconds is an extremely long
>>> commit, which is usually caused by excessive cache autowarming, but
>>> might be related to insufficient memory.  The max heap setting on an
>>> out-of-the-box Solr install (5.0 and later) is 512MB.  That's VERY
>>> small, and it doesn't take much index data before a much larger heap
>>> is required.
>>> Thanks,
>>> Shawn
>> I looked into the code (version 2.3.5.1): the fts-solr plugin is not
>> sending softCommit every 1000 emails. Emails from a single folder are
>> batched in up to a maximum of 1000 emails per request, but the
>> softCommit gets sent once per mailbox folder at the end of all the
>> requests for that folder.
>>
>> I immagine that one of the reasons dovecot sends softCommits is because
>> without autoindex active and even if mailboxes are periodically indexed
>> from cron, the last emails received with be indexed at the moment of the
>> search.  So while sending softCommit has the advantage of including
>> recent mails in searches, it means that softCommits are being done upon
>> user request. Frequency depends on user activity.
>>
>> Going back to the original problem: seems the first advice to Peter is
>> to look into solr configuration as others have said.
>>
>> From dovecot point of view I can see the following as potentially useful
>> features:
>>
>> 1) a configurable batch size would enable to tune the number of emails
>> per request and help stay under the 60 seconds hard coded http request
>> timeout. A configurable http timeout would be less useful, since this
>> will potentially run into other timeouts on solr side.
>>
>> 2) abilty to turn off softCommits so as to have a more predictable
>> softCommit workload. In that case autoSoftCommit should be configured in
>> solr. In order to minimize risk of recent emails not appearing in search
>> results, periodic indexing could be set up by cron.
>>
>> I've attached a patch, any comments are welcome (especially about
>> getting settings from the backend context).
>>
>> Example config
>>
>> plugin {
>>   fts = solr
>>   fts_solr =
>> url= https://user:password@solr.example.com:443/solr/dovecot/
>> batch_size=500 no_soft_commit
>> }
>>
>> John
>
> Can you please open a pull request to https://github.com/dovecot/core ?
> ---
> Aki Tuomi

Done, thanks for considering it.

John

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