Flush idle database connections

1 files changed, 58 insertions, 16 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 6c06f67239..94687b9bb7 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -63,15 +63,13 @@ module ActiveRecord
     # There are several connection-pooling-related options that you can add to
     # your database connection configuration:
     #
-    # * +pool+: number indicating size of connection pool (default 5)
-    # * +checkout_timeout+: number of seconds to block and wait for a connection
-    #   before giving up and raising a timeout error (default 5 seconds).
-    # * +reaping_frequency+: frequency in seconds to periodically run the
-    #   Reaper, which attempts to find and recover connections from dead
-    #   threads, which can occur if a programmer forgets to close a
-    #   connection at the end of a thread or a thread dies unexpectedly.
-    #   Regardless of this setting, the Reaper will be invoked before every
-    #   blocking wait. (Default +nil+, which means don't schedule the Reaper).
+    # * +pool+: maximum number of connections the pool may manage (default 5).
+    # * +idle_timeout+: number of seconds that a connection will be kept
+    #   unused in the pool before it is automatically disconnected (default
+    #   300 seconds). Set this to zero to keep connections forever.
+    # * +checkout_timeout+: number of seconds to wait for a connection to
+    #   become available before giving up and raising a timeout error (default
+    #   5 seconds).
     #
     #--
     # Synchronization policy:
@@ -280,12 +278,12 @@ module ActiveRecord
           end
       end
 
-      # Every +frequency+ seconds, the reaper will call +reap+ on +pool+.
-      # A reaper instantiated with a +nil+ frequency will never reap the
-      # connection pool.
+      # Every +frequency+ seconds, the reaper will call +reap+ and +flush+ on
+      # +pool+. A reaper instantiated with a zero frequency will never reap
+      # the connection pool.
       #
-      # Configure the frequency by setting "reaping_frequency" in your
-      # database yaml file.
+      # Configure the frequency by setting +reaping_frequency+ in your database
+      # yaml file (default 60 seconds).
       class Reaper
         attr_reader :pool, :frequency
 
@@ -295,11 +293,12 @@ module ActiveRecord
         end
 
         def run
-          return unless frequency
+          return unless frequency && frequency > 0
           Thread.new(frequency, pool) { |t, p|
             loop do
               sleep t
               p.reap
+              p.flush
             end
           }
         end
@@ -323,6 +322,10 @@ module ActiveRecord
         @spec = spec
 
         @checkout_timeout = (spec.config[:checkout_timeout] && spec.config[:checkout_timeout].to_f) || 5
+        if @idle_timeout = spec.config.fetch(:idle_timeout, 300)
+          @idle_timeout = @idle_timeout.to_f
+          @idle_timeout = nil if @idle_timeout <= 0
+        end
 
         # default max pool size to 5
         @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5
@@ -353,7 +356,10 @@ module ActiveRecord
 
         @lock_thread = false
 
-        @reaper = Reaper.new(self, spec.config[:reaping_frequency] && spec.config[:reaping_frequency].to_f)
+        # +reaping_frequency+ is configurable mostly for historical reasons, but it could
+        # also be useful if someone wants a very low +idle_timeout+.
+        reaping_frequency = spec.config.fetch(:reaping_frequency, 60)
+        @reaper = Reaper.new(self, reaping_frequency && reaping_frequency.to_f)
         @reaper.run
       end
 
@@ -572,6 +578,35 @@ module ActiveRecord
         end
       end
 
+      # Disconnect all connections that have been idle for at least
+      # +minimum_idle+ seconds. Connections currently checked out, or that were
+      # checked in less than +minimum_idle+ seconds ago, are unaffected.
+      def flush(minimum_idle = @idle_timeout)
+        return if minimum_idle.nil?
+
+        idle_connections = synchronize do
+          @connections.select do |conn|
+            !conn.in_use? && conn.seconds_idle >= minimum_idle
+          end.each do |conn|
+            conn.lease
+
+            @available.delete conn
+            @connections.delete conn
+          end
+        end
+
+        idle_connections.each do |conn|
+          conn.disconnect!
+        end
+      end
+
+      # Disconnect all currently idle connections. Connections currently checked
+      # out are unaffected.
+      def flush!
+        reap
+        flush(-1)
+      end
+
       def num_waiting_in_queue # :nodoc:
         @available.num_waiting
       end
@@ -921,6 +956,13 @@ module ActiveRecord
         connection_pool_list.each(&:disconnect!)
       end
 
+      # Disconnects all currently idle connections.
+      #
+      # See ConnectionPool#flush! for details.
+      def flush_idle_connections!
+        connection_pool_list.each(&:flush!)
+      end
+
       # Locate the connection of the nearest super class. This can be an
       # active or defined connection: if it is the latter, it will be
       # opened and set as the active connection for the class it was defined