use redis connection pool for cache purge

environment.rb

@@ -51,7 +51,9 @@ Sidekiq.configure_client do |config|
 end
 
 if $config['pubsub_url']
-  $pubsub = Redis.new url: $config['pubsub_url'] 
+  $pubsub_pool = ConnectionPool.new(size: 10, timeout: 5) {
+    Redis.new url: $config['pubsub_url']
+  }
 end
 
 if $config['pubsub_url'].nil? && ENV['RACK_ENV'] == 'production'

workers/purge_cache_worker.rb

@@ -6,7 +6,9 @@ class PurgeCacheWorker
     attempt = 0
     begin
       attempt += 1
-      $pubsub.publish 'purgecache', payload.to_json
+      $pubsub_pool.with do |redis|
+        redis.publish 'purgecache', payload.to_json
+      end
     rescue Redis::BaseConnectionError => error
       raise if attempt > 3
       puts "pubsub error: #{error}, retrying in 1s"