[Postgres-xl-general] "ERROR: Failed to get pooled connections" with cross-node join

Pavan Deolasee pavan.deolasee at gmail.com
Thu Oct 1 10:03:40 PDT 2015


On Thu, Oct 1, 2015 at 9:58 PM, Tobias Oberstein <tobias.oberstein at gmail.com
> wrote:

> Try increasing max_pool_size on the datanodes too.
>>
>
> Ok, increased to 2048 as well. Rebuilt whole cluster and test data. Same
> issue.
>
> There are some compile time #defines for worker threads etc, but other
>> than that there is no tunable for GTM.
>>
>
> FWIW, when stuff breaks, I see 10k's of messages like the following in the
> GTM log:
>
> 1:139736683767552:2015-10-01 17:46:32.257 CEST -LOG:  unexpected EOF on
> client connection
> LOCATION:  ReadCommand, main.c:1481
>
> 1:139769623611136:2015-10-01 17:46:34.727 CEST -LOG:  Too many threads
> active
> LOCATION:  GTM_ThreadAdd, gtm_thread.c:53
>
>
Krzysztof may have corrected nailed it down to the GTM_MAX_THREADS limit
which looks likely given that you are running without the proxy.

>
>>
> Huh, ok. That is a bummer. 16 nodes is nothing. What we are aiming for is
> scaling to at least 256 nodes (4 boxes a 4 sockets a 16 cores) and
> parallelize to a degree of perhaps 64.
>

I would think it should still be possible. We are definitely working on
improving stability and performance and hope we get there by the time we go
GA with XL 9.5. But at the same time, its hard to promise anything given
that we are still running with limited resources on the project.

I recently heard that some company (I am not sure if I am allowed to take
name) is planning to go into production with 100+ nodes. But the workload
could be quite different or may be same as yours. Don't have much insight
into it right now.


> I totally understand. My problem is: I am expected to give an opinion on
> feasibility of using PG-XL to drive a finance DWH now. Hell, I'd be happy
> to recommend PG-XL. But. And after reading through the dev list, I have
> more questions ..
>
>
Sure. Together we can make it a better product for sure :-)

Thanks,
Pavan

-- 
 Pavan Deolasee                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services
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