many workers threads failed with EAGAIN

[Poul-Henning Kamp]

In message <dcccdf790908310536m155a49cfw770c04657aab1ab6 at mail.gmail.com>, David
 Birdsong writes:
>varnishlog has a lot of these:
> 0 Debug        - "Create worker thread failed 11 Resource temporarily
>unavailable"
>
>sure enough, overflowed and dropped work requests are steadily on the rise
>Hitrate ratio:       10      100     1000
>Hitrate avg:     0.8584   0.8506   0.8581

>        1007          .            .   N worker threads
>        1007         0.00         0.34 N worker threads created
>       12425         4.00         4.20 N worker threads not created
>        2002         1.00         0.68 N queued work requests
>      651706       157.04       220.47 N overflowed work requests
>      460396       262.07       155.75 N dropped work requests

It is not clear to me why you ended up needing so many threads,
but the usualy explanation is comms problems either in client
or backend direction.

If you have not enabled backend probing, you should do so, since that
prevents the threads from getting stuck on a troubled backend.

Poul-Henning

-- 
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