diff --git a/lib/mongo/collection.rb b/lib/mongo/collection.rb
index a58f4ce..d91e186 100644
--- a/lib/mongo/collection.rb
+++ b/lib/mongo/collection.rb
@@ -53,7 +53,7 @@ module Mongo
     def initialize(name, db, opts={})
       if db.is_a?(String) && name.is_a?(Mongo::DB)
         warn "Warning: the order of parameters to initialize a collection have changed. " +
-             "Please specify the collection name first, followed by the db. This will be made permanent"
+             "Please specify the collection name first, followed by the db. This will be made permanent" +
              "in v2.0."
         db, name = name, db
       end
diff --git a/lib/mongo/connection.rb b/lib/mongo/connection.rb
index 63afd39..5e97d2f 100644
--- a/lib/mongo/connection.rb
+++ b/lib/mongo/connection.rb
@@ -30,9 +30,6 @@ module Mongo
     Mutex = ::Mutex
     ConditionVariable = ::ConditionVariable
 
-    # Abort connections if a ConnectionError is raised.
-    Thread.abort_on_exception = true
-
     DEFAULT_PORT = 27017
     STANDARD_HEADER_SIZE = 16
     RESPONSE_HEADER_SIZE = 20
diff --git a/lib/mongo/repl_set_connection.rb b/lib/mongo/repl_set_connection.rb
index bf63c50..012cd3a 100644
--- a/lib/mongo/repl_set_connection.rb
+++ b/lib/mongo/repl_set_connection.rb
@@ -23,7 +23,7 @@ module Mongo
   # Instantiates and manages connections to a MongoDB replica set.
   class ReplSetConnection < Connection
     attr_reader :nodes, :secondaries, :arbiters, :secondary_pools,
-      :replica_set_name, :read_pool, :seeds, :tags_to_pools, :refresh_interval
+      :replica_set_name, :read_pool, :seeds, :tags_to_pools, :refresh_interval, :auto_refresh
 
     # Create a connection to a MongoDB replica set.
     #
@@ -62,6 +62,8 @@ module Mongo
     #   prevent you from having to reconnect manually.
     # @option opts [Integer] :refresh_interval (90) If :auto_refresh is enabled, this is the number of seconds
     #   that the background thread will sleep between calls to check the replica set's state.
+    # @option opts [Boolean] :require_primary (true) If true, require a primary node for the connection
+    #   to succeed. Otherwise, connection will succeed as long as there's at least one secondary.
     #
     # @example Connect to a replica set and provide two seed nodes. Note that the number of seed nodes does
     #   not have to be equal to the number of replica set members. The purpose of seed nodes is to permit
@@ -148,6 +150,9 @@ module Mongo
         @replica_set_name = opts[:name]
       end
 
+      # Require a primary node to connect?
+      @require_primary = opts.fetch(:require_primary, false)
+
       setup(opts)
     end
 
@@ -158,6 +163,7 @@ module Mongo
 
     # Initiate a connection to the replica set.
     def connect
+      log(:debug, "Connecting.")
       sync_synchronize(:EX) do
         return if @connected
         manager = PoolManager.new(self, @seeds)
@@ -166,8 +172,10 @@ module Mongo
         update_config(manager)
         initiate_auto_refresh
 
-        if @primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
+        if @require_primary && @primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
           raise ConnectionFailure, "Failed to connect to primary node."
+        elsif !@read_pool
+          raise ConnectionFailure, "Failed to connect to any node."
         else
           @connected = true
         end
@@ -205,11 +213,14 @@ module Mongo
       end
 
       background_manager = Thread.current[:background]
-      if background_manager.update_required?(@hosts)
-        sync_synchronize(:EX) do
-          background_manager.connect
-          update_config(background_manager)
-        end
+
+      # Return if another thread is already in the process of refreshing.
+      return if sync_exclusive?
+
+      sync_synchronize(:EX) do
+        log(:debug, "Refreshing...")
+        background_manager.connect
+        update_config(background_manager)
       end
     end
 
@@ -259,35 +270,36 @@ module Mongo
     # Close the connection to the database.
     # TODO: we should get an exclusive lock here.
     def close
-      @connected = false
+      sync_synchronize(:EX) do
+        @connected = false
+        super
 
-      super
-
-      if @refresh_thread
-        @refresh_thread.kill
-        @refresh_thread = nil
-      end
-
-      if @nodes
-        @nodes.each do |member|
-          member.disconnect
+        if @refresh_thread
+          @refresh_thread.kill
+          @refresh_thread = nil
         end
-      end
 
-      @nodes = []
-      @read_pool = nil
-
-      if @secondary_pools
-        @secondary_pools.each do |pool|
-          pool.close
+        if @nodes
+          @nodes.each do |member|
+            member.disconnect
+          end
         end
-      end
 
-      @secondaries     = []
-      @secondary_pools = []
-      @arbiters        = []
-      @tags_to_pools.clear
-      @sockets_to_pools.clear
+        @nodes = []
+        @read_pool = nil
+
+        if @secondary_pools
+          @secondary_pools.each do |pool|
+            pool.close
+          end
+        end
+
+        @secondaries     = []
+        @secondary_pools = []
+        @arbiters        = []
+        @tags_to_pools.clear
+        @sockets_to_pools.clear
+      end
     end
 
     # If a ConnectionFailure is raised, this method will be called
@@ -342,17 +354,25 @@ module Mongo
     # if no read pool has been defined.
     def checkout_reader
       connect unless connected?
+      socket = get_socket_from_pool(@read_pool)
 
-      sync_synchronize(:SH) do
-        socket = @read_pool.checkout
-        @sockets_to_pools[socket] = @read_pool
+      if !socket
+        refresh
+        socket = get_socket_from_pool(@primary_pool)
+      end
+
+      if socket
         socket
+      else
+        raise ConnectionFailure.new("Could not connect to a node for reading.")
       end
     end
 
     # Checkout a socket connected to a node with one of
     # the provided tags. If no such node exists, raise
     # an exception.
+    #
+    # NOTE: will be available in driver release v2.0.
     def checkout_tagged(tags)
       sync_synchronize(:SH) do
         tags.each do |k, v|
@@ -372,13 +392,33 @@ module Mongo
     # Checkout a socket for writing (i.e., a primary node).
     def checkout_writer
       connect unless connected?
+      socket = get_socket_from_pool(@primary_pool)
 
-      sync_synchronize(:SH) do
-        if @primary_pool
-          socket = @primary_pool.checkout
-          @sockets_to_pools[socket] = @primary_pool
-          socket
+      if !socket
+        refresh
+        socket = get_socket_from_pool(@primary_pool)
+      end
+
+      if socket
+        socket
+      else
+        raise ConnectionFailure.new("Could not connect to primary node.")
+      end
+    end
+
+    def get_socket_from_pool(pool)
+      begin
+        sync_synchronize(:SH) do
+          if pool
+            socket = pool.checkout
+            @sockets_to_pools[socket] = pool
+            socket
+          end
         end
+
+      rescue ConnectionFailure => ex
+        log(:info, "Failed to checkout from #{pool} with #{ex.class}; #{ex.message}")
+        return nil
       end
     end
 
@@ -397,8 +437,12 @@ module Mongo
     end
 
     def checkin(socket)
-      if pool = @sockets_to_pools[socket]
-        pool.checkin(socket)
+      sync_synchronize(:SH) do
+        if pool = @sockets_to_pools[socket]
+          pool.checkin(socket)
+        elsif socket
+          socket.close
+        end
       end
     end
   end
diff --git a/lib/mongo/util/logging.rb b/lib/mongo/util/logging.rb
index 714565a..e3fde4c 100644
--- a/lib/mongo/util/logging.rb
+++ b/lib/mongo/util/logging.rb
@@ -2,7 +2,7 @@ module Mongo
   module Logging
 
     # Log a message with the given level.
-    def log(level, message)
+    def log(level, msg)
       return unless @logger
       case level
         when :debug then
diff --git a/lib/mongo/util/node.rb b/lib/mongo/util/node.rb
index fc7f3fd..5b4c81c 100644
--- a/lib/mongo/util/node.rb
+++ b/lib/mongo/util/node.rb
@@ -20,6 +20,10 @@ module Mongo
     end
     alias :== :eql?
 
+    def close
+      self.socket.close if self.socket
+    end
+
     def host_string
       address
     end
diff --git a/lib/mongo/util/pool.rb b/lib/mongo/util/pool.rb
index 0f962af..13f3f15 100644
--- a/lib/mongo/util/pool.rb
+++ b/lib/mongo/util/pool.rb
@@ -52,17 +52,19 @@ module Mongo
     end
 
     def close
-      @sockets.each do |sock|
-        begin
-          sock.close
-        rescue IOError => ex
-          warn "IOError when attempting to close socket connected to #{@host}:#{@port}: #{ex.inspect}"
+      @connection_mutex.synchronize do
+        (@sockets - @checked_out).each do |sock|
+          begin
+            sock.close
+          rescue IOError => ex
+            warn "IOError when attempting to close socket connected to #{@host}:#{@port}: #{ex.inspect}"
+          end
         end
+        @host = @port = nil
+        @sockets.clear
+        @pids.clear
+        @checked_out.clear
       end
-      @host = @port = nil
-      @sockets.clear
-      @pids.clear
-      @checked_out.clear
     end
 
     def inspect
@@ -188,7 +190,7 @@ module Mongo
       if @pids[socket] != Process.pid
          @pids[socket] = nil
          @sockets.delete(socket)
-         socket.close
+         socket.close if socket
          checkout_new_socket
       else
         @checked_out << socket
diff --git a/lib/mongo/util/pool_manager.rb b/lib/mongo/util/pool_manager.rb
index a7ce367..0a57a6e 100644
--- a/lib/mongo/util/pool_manager.rb
+++ b/lib/mongo/util/pool_manager.rb
@@ -23,31 +23,29 @@ module Mongo
       @members = members
     end
 
-    # Ensure that the view of the replica set is current by
-    # running the ismaster command and checking to see whether
-    # we've connected to all known nodes. If not, automatically
-    # connect to these unconnected nodes. This is handy when we've
-    # connected to a replica set with no primary or when a secondary
-    # node comes up after we've connected.
-    #
-    # If we're connected to nodes that are no longer part of the set,
-    # remove these from our set of secondary pools.
-    def update_required?(hosts)
-      if !@refresh_node || !@refresh_node.set_config
-        begin
-          @refresh_node = get_valid_seed_node
-        rescue ConnectionFailure
-          warn "Could not refresh config because no valid seed node was available."
-          return
-        end
-      end
-
-      hosts != @refresh_node.node_list
-    end
-
     private
 
     def initialize_data
+      begin
+        if @primary_pool
+          @primary_pool.close
+        end
+
+        if @secondary_pools
+          @secondary_pools.each do |pool|
+            pool.close
+          end
+        end
+
+        if @members
+          @members.each do |member|
+            member.close
+          end
+        end
+
+        rescue ConnectionFailure
+      end
+
       @primary = nil
       @primary_pool = nil
       @read_pool = nil
diff --git a/test/replica_sets/refresh_test.rb b/test/replica_sets/refresh_test.rb
index f35d04d..7368574 100644
--- a/test/replica_sets/refresh_test.rb
+++ b/test/replica_sets/refresh_test.rb
@@ -6,6 +6,10 @@ require 'benchmark'
 class ReplicaSetRefreshTest < Test::Unit::TestCase
   include Mongo
 
+  def setup
+    @conn = nil
+  end
+
   def teardown
     RS.restart_killed_nodes
     @conn.close if @conn
@@ -98,7 +102,6 @@ class ReplicaSetRefreshTest < Test::Unit::TestCase
   end
 
   def test_adding_and_removing_nodes
-    puts "ADDING AND REMOVING"
     @conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
       [RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
 
diff --git a/test/tools/repl_set_manager.rb b/test/tools/repl_set_manager.rb
index 5ee8e53..6369648 100644
--- a/test/tools/repl_set_manager.rb
+++ b/test/tools/repl_set_manager.rb
@@ -21,7 +21,7 @@ class ReplSetManager
     @config     = {"_id" => @name, "members" => []}
     @durable    = opts.fetch(:durable, false)
     @path       = File.join(File.expand_path(File.dirname(__FILE__)), "data")
-    @oplog_size = opts.fetch(:oplog_size, 512)
+    @oplog_size = opts.fetch(:oplog_size, 32)
     @tags = [{"dc" => "ny", "rack" => "a", "db" => "main"},
              {"dc" => "ny", "rack" => "b", "db" => "main"},
              {"dc" => "sf", "rack" => "a", "db" => "main"}]