benchmark socket limit > 1018? ubuntu 20.04

[hst-m]

when I run benchmark with connection size greater than 1018 ./load_test 2000 localhost 3001 0 getaddrinfo in uSockets throws System error "Device or resource busy" when opening the 1019 connection and it stops running. Any idea how to fix this? Ubuntu 20.04

getaddrinfo source for this error:
https://github.com/bminor/glibc/blob/master/sysdeps/posix/getaddrinfo.c#L887-L897
"The root cause could .. be a resource allocation failure .. return EBUSY"

[ghost]

Probably ulimit related, or similar. Increase allowed FDs