pgbench bug / limitation

Hello Team,

I was using pgbench to run benchmarking tests on our postgres server and came across this issue which I feel is pgbench bug.
I had initialized the test DB with scale factor 200. And then started the test with clients (-c 150) but it never worked until I reduced the clients to 115.
Below is the error message.

OS: Windows 10
Version: pgbench (PostgreSQL) 12.2
Max Connection allowed on Server: 800

C:\Program Files\PostgreSQL\12\bin>pgbench.exe -i -s 200 -h <DBServerName> -p 9432 -U DBUser testdb

C:\Program Files\PostgreSQL\12\bin>pgbench.exe -c 122 -r -T 3600 -h <DBServerName> -p 9432 -U DBUser testdb
Password:
starting vacuum...end.
too many client connections for select()

C:\Program Files\PostgreSQL\12\bin>pgbench.exe -c 120 -r -T 3600 -h <DBServerName> -p 9432 -U DBUser testdb
Password:
starting vacuum...end.
too many client connections for select()

Thanks
Manish