Loom and high performance networking

[Alan Bateman]

On 13/08/2024 12:25, Robert Engels wrote:
> :
>
> Using VT pollers (pollerMode=2) and default parallelism:
>
> robertengels at macmini go-wrk %  wrk -H 'Host: imac' -H 'Accept: 
> text/plain,text/html;q=0.9,application/xhtml+xml;q=0.9,application/xml;q=0.8,*/*;q=0.7' 
> -H 'Connection: keep-alive' --latency -d 20 -c 1000 --timeout 8 -t 8 
> http://imac:8080/plaintext 
> <https://urldefense.com/v3/__http://imac:8080/plaintext__;!!ACWV5N9M2RV99hQ!OSop_Xwpde2E9iW4xAOJ-iUfPMQ4NDkHxIr3S7UmvlgiGk94boiQLh9ZO6Btn1uwp6HY3TYdhv9yzjU8$>
> Running 20s test @ http://imac:8080/plaintext 
> <https://urldefense.com/v3/__http://imac:8080/plaintext__;!!ACWV5N9M2RV99hQ!OSop_Xwpde2E9iW4xAOJ-iUfPMQ4NDkHxIr3S7UmvlgiGk94boiQLh9ZO6Btn1uwp6HY3TYdhv9yzjU8$>
>   8 threads and 1000 connections
>   Thread Stats   Avg      Stdev     Max   +/- Stdev
>     Latency    66.76ms  137.25ms   1.70s 87.06%
>     Req/Sec    14.38k     2.36k   21.94k 75.88%
>   Latency Distribution
>      50%    4.74ms
>      75%   51.68ms
>      90%  263.08ms
>      99%  664.99ms
>   2289858 requests in 20.02s, 310.10MB read
>   Socket errors: connect 0, read 2135, write 7, timeout 0
> Requests/sec: 114360.91
> Transfer/sec:     15.49MB
>
> and the same 8% idle.
>
> So I am pretty sure my hypothesis is correct. I may try and build a 
> Loom / use a library to lower priority of the carrier threads. I 
> suspect I will see similar performance to the reduced parallelism case.

With -Djdk.pollerMode=2 then the poller threads are virtual threads and 
so run on the same carrier. You'll need to play with -Djdk.readPollers=N 
as there isn't a good default for this on macOS.

-Alan.
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