Re: Overhead of load-balanced microservices architecture

Hi Doug!

Thanks for sharing. This reminds me of the famous Torvalds vs Tanenbaum debate. Andrew Tanenbaum, a famous university professor and a designer of the still popular Minix operating system admonished Linux Torvalds, even more famous designer of the Linux OS, for not using micro-kernel architecture. While debate itself was extremely technical, as can be expected from the two top notch OS experts, the winning argument by Linus Torvalds was - performance. Micro kernel architecture requires a lot of inter-process communication and the monolithic architecture simply performs better. Here is the Wikipedia entry about the debate:

https://en.wikipedia.org/wiki/Tanenbaum%E2%80%93Torvalds_debate

Now, what does this famous debate has to do with ever more popular microservices architecture? Microservices architecture essentially requires re-architecting the application as a bunch of micro-services which have to talk to one another, in order for the whole system to function. The advantages are twofold: easier debugging because each micro-service is a separate unit and easier adjustment to the container technologies like Docker or Kubernetes which are usually advertised as "lightweight virtualization". Well, the opposing principles are the same: a bunch of chatty services which have to constantly talk to one another in order to check that everything is working as it should vs. large application which is harder to debug and harder to put into a container, but doesn't have radical communication requirements. The solution is relatively simple: the microservices will have to separate status data from the user data and use something else for status exchange, something like MySQL. That would not make the microservices cheaper, it will just make them consume the cheaper resource. That, however, requires another round of programming which might not be so cheap.

Regards

On 8/13/20 12:34 AM, DOUG KUSHNER wrote:
>
> Our dev team recently rolled out an application using an F5
> load-balanced microservices architecture.  There are several
> miscroservices, each load balanced on up to 4 servers each, and each
> with a health-check api that hits the database.  While this may have
> looked good on paper, just the overhead of the health-checks with no
> work being processed has resulted in roughly 7 connection attempts per
> second to the database.  This results in a version check query about
> 40K times per hour.  The database is on an Exadata (2-node RAC) with
> several other production databases.
>
> Of course the Exadata has been handling it, so unless you are looking
> for anomalies (which I always am), this will fly under the radar until
> it doesn't. :)
>
> I'm wondering if anyone knows how to determine the theoretical max
> connections/sec that a listener can handle based on the number of
> cores licensed in the system?
>
> Also wondering if anyone here has encountered this scenario before and
> how they dealt with it.  I'm also looking for a good reference on the
> subject.
>
> My immediate focus will be on determining why these health check
> connections do not appear to be utilizing the services' connection
> pools, while the dev team determines whether they can relax the
> frequency of these health checks.
>
> Regards,
>
> Doug
>

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217

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