Performance Degradation due to the change to `poll()` from `select()`

[yhirose]

From 6e73a63, the benchmark tells the server performance is degraded on my M1 MacBook Pro.

cdc2230

[(cdc2230...)] ~/cpp-httplib/benchmark$ make
--------------------
 cpp-httplib latest
--------------------

Bombarding http://localhost:8080 for 5s using 10 connection(s)
[========================================================================================] 5s
Done!
Statistics        Avg      Stdev        Max
  Reqs/sec     56801.52    2552.63   60463.11
  Latency      174.29us    30.21us     3.87ms
  HTTP codes:
    1xx - 0, 2xx - 283995, 3xx - 0, 4xx - 0, 5xx - 0
    others - 0
  Throughput:     9.26MB/s

6e73a63

[(6e73a63...)] ~/cpp-httplib/benchmark$ make
g++ -o server -std=c++11 -O2 -I.. -DCPPHTTPLIB_THREAD_POOL_COUNT=16 cpp-httplib/main.cpp
--------------------
 cpp-httplib latest
--------------------

Bombarding http://localhost:8080 for 5s using 10 connection(s)
[========================================================================================] 5s
Done!
Statistics        Avg      Stdev        Max
  Reqs/sec     45686.36    4232.86   49142.01
  Latency      217.01us    54.15us     6.39ms
  HTTP codes:
    1xx - 0, 2xx - 225098, 3xx - 0, 4xx - 0, 5xx - 0
    others - 3339
  Errors:
    dial tcp [::1]:8080: connect: connection refused - 3339
  Throughput:     7.34MB/s

[falbrechtskirchinger]

Ouch. I have 3 immediate ideas I want to try. My schedule is a bit uncertain over the next 4-5 days, and I don't know if I have time beyond the cpp-httplib issues I've already committed to. But I will look into it once I'm free. Thank you for your patience!

Edit: Oh, and seeing as this is on macOS, I'll first have to replicate it on Linux.

[yhirose]

@falbrechtskirchinger, No rush! It's totally fine to work on this whenever you are available. (I also work on this project in my spare time. 😃)

[yhirose]

@falbrechtskirchinger did you have a chance to take a look at this, yet?

[yhirose]

@falbrechtskirchinger if you don't find any solution, could you please revert #2078? Thanks!