write does not block ?

example.rb

# server.rb
require 'socket'
server = TCPServer.new 4000 
loop do
  client = server.accept
  p client.recv(10)
  p "HERE"

  loop
end

#client.rb
require 'socket'
s = TCPSocket.open('localhost', 4000)
p s.write("A"*1000)
p "HERE"