I'm seeing sporadic errors like this on 64-bit Cygwin when I first start emacs:

       0 [main] emacs-X11 864 C:\cygwin64\bin\emacs-X11.exe: *** fatal error in 
forked process - Can't recreate shared timerfd section during fork!
       0 [main] emacs 860 dofork: child 864 - died waiting for dll loading, errno 11

If I exit and restart, everything will be fine almost every time.

On 32-bit Cygwin, I don't get an error on startup.  But I consistently get an 
error when I try to list a directory within emacs (emacs is forking a subprocess 
that calls 'ls').  I don't see any error message on the terminal in this case, 
and the error message in emacs isn't informative.

In both the 64-bit and 32-bit cases, I've installed the 20190223 snapshot.

I'm attaching the output from attaching strace to emacs (32-bit case) right 
before trying to list a directory.  I can try to make an STC if the strace 
output isn't helpful, but I won't have time to do that today.  Presumably the 
key elements are to start a timerfd timer, call select on it (possibly in a 
loop), and fork a subprocess.

Ken