Performance degradation on LRU nuking

[Ameya Prabhu]

Thanks Nils. What were the shortcomings that you were trying to improve ?
Did any of the releases post v6.1 show any improvement ?

On Tue, Sep 1, 2020 at 10:01 AM Nils Goroll <slink at schokola.de> wrote:

> On 01/09/2020 15:52, Ameya Prabhu wrote:
>
>
> We are seeing performance issues with Varnish’s file storage when the
> storage reaches its capacity and Varnish starts LRU nuking. As soon as
> varnish begins nuking objects, the number of worker threads(MAIN.threads)
> starts increasing until it hits the limit(thread_pool_max) and remains
> pinned on the thread_pool_max. This then leads to incoming requests getting
> queued.
>
> some 12-18 months back, I made an effort to prototype improvements to the
> LRU nuking, but never reached an anything mature enough for a pull request.
>
> That said, in my case I used malloc storage and the issue was high lock
> contention. As you mention you are using file storage, I would suspect that
> IO performance could be the bottleneck.
>
> There is no magic knob I would be aware of, other than using more RAM and
> faster IO.
>
> Nils
>
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