Throwing three non-pausing clients at mysql-backed EM server

is causing intermittent port binding problems which
manifest as an unreachable server.  Inserting a pause
on the client side fixes the problem.  Hm.

ruby-sockets/marco-polo/client.rb

@@ -1,11 +1,25 @@
 require 'socket'
 
+successes = 0
+backoff = 0.5
 loop do
-  TCPSocket.open('127.0.0.1', 22000) do |sock|
-    sock.send("sally #{rand(100)} #{rand(100)}\n", 0)
-    sock.recv(100)
-    sock.close
-    STDOUT.write('.')
+  begin
+    TCPSocket.open('127.0.0.1', 22000) do |sock|
+      sock.send("sally #{rand(101)} #{rand(101)}\n", 0)
+      sock.recv(100)
+      sock.close
+      STDOUT.write('.')
+      STDOUT.flush
+    end
+    successes += 1
+    backoff = 0.5
+    sleep 0.01
+  rescue
+    STDOUT.write('E')
     STDOUT.flush
+    STDERR.write("\nmade it #{successes} times. sleeping #{backoff} secs\n")
+    successes = 0
+    sleep backoff
+    backoff *= 2
   end
 end

ruby-sockets/marco-polo/em-server.rb

@@ -1,10 +1,16 @@
 require 'eventmachine'
 require 'sequel'
 
-DB = Sequel.connect('sqlite://marco-polo.sqlite3')
+if ENV['MPDB']
+  DB = Sequel.connect(ENV['MPDB'])
+else
+  DB = Sequel.connect('sqlite://marco-polo.sqlite3')
+end
 
-if DB[:locations].nil?
-  DB.create_table :locations do
+begin
+  DB[:locations].empty?
+rescue Sequel::DatabaseError
+  DB.create_table(:locations) do
     primary_key :id
     String :client
     Integer :x