1.3.0 version slow on Windows

[jirubio]

This is my environment:
Rails 6.1.4.4
Ruby 2.7.4
PostgreSQL 12.6
OS Windows 10

PG gem 1.2.3 is working fine for me, but it does not support ruby 3. So I upgraded to the latest version 1.3.0.rc3. It installed without complaints and the rails app runs ok. I noticed some slowness so I compared 1.2.3 against 1.3.0 and the latter is really slow.
For our main page which does nothing rare, standard selects it went from 120ms to 600ms, same results for other pages. This is a 5x performance hit. Maybe 1.3.0 is not yet optimized for windows.
This is currently blocking our upgrade to ruby 3.

[larskanis]

I can confirm this slow down. pg-1.3.0-rc3 is slower by a factor of 5 to 10 than pg-1.2.3 on Windows.

I guess it's due to #397 , which changed quite a lot in the socket handling code. Now the Windows socket code is no longer a separate path, but is equal to the Posix code. Both are using the same ruby functions for READ/WRITE event notifications on the network socket. This is rb_io_wait() on ruby-3.0+ and rb_wait_for_single_fd() on ruby-2.x. So it looks like these ruby functions are much slower than the previous rb_w32_wait_events().

[larskanis]

I pushed a new pre-release pg-1.3.0.rc4, which should fix this performance issue.

[jirubio]

That was fast! Performance issue seems to be fixed, thanks Lars.