Merge #339: checkpoint SQLite WAL outside request threads

lib/tasks/resque.rake

@@ -4,9 +4,13 @@ end
 
 task "resque:pool:setup" do
   ActiveRecord::Base.connection.disconnect!
+  # Initializer may have started a contender in the pool master; drop it before
+  # workers fork so they do not inherit the flock.
+  SqliteWalCheckpoint.stop
 
   Resque::Pool.after_prefork do |job|
     ActiveRecord::Base.establish_connection
     Resque.redis.client.close
+    SqliteWalCheckpoint.start
   end
 end