#72 fixed! [user.tcp] accept tcp [::]:5000: accept4: too many open files was due to the allowance of limited number of open file descriptors by the operating system. There was no deadline set for opened connections so most of the connections never get closed. In result, the number of opened connections gradually cross the maximum open file descriptors limit and cause panic.
Now with connection timeout = 72 second, number of opened connection will never reach the open file descriptor limit.