我正在从网站下载一些图像并使用 Paperclip 将这些图像上传到 S3 存储桶。加载图像后，我将一个实体存储到数据库中并返回它。这包含在Rails.cache.fetch缓存响应的调用中。
它是这样的。
Rails.cache.fetch("/tvshows/#{id}/images") do
result = self.find(id)
if result.image.nil?
result = self.load_image(result)
end
result
end
但是，图像将开始下载，最终我将获得IOError - closed stream:以下堆栈。
谁能告诉我为什么会出现此错误以及如何避免它？
IOError - closed stream:
redis-store (1.1.4) lib/redis/store/marshalling.rb:29:in `_marshal'
redis-store (1.1.4) lib/redis/store/marshalling.rb:5:in `set'
redis-activesupport (4.0.0) lib/active_support/cache/redis_store.rb:163:in `write_entry'
redis-activesupport (4.0.0) lib/active_support/cache/redis_store.rb:36:in `block in write'
activesupport (4.2.0) lib/active_support/cache.rb:547:in `block in instrument'
activesupport (4.2.0) lib/active_support/notifications.rb:166:in `instrument'
activesupport (4.2.0) lib/active_support/cache.rb:547:in `instrument'
redis-activesupport (4.0.0) lib/active_support/cache/redis_store.rb:34:in `write'
activesupport (4.2.0) lib/active_support/cache.rb:588:in `save_block_result_to_cache'
activesupport (4.2.0) lib/active_support/cache.rb:299:in `fetch'
app/models/tv_show.rb:30:in `find_images'
app/controllers/api/v1/tv_shows.rb:35:in `block (3 levels) in <class:TvShows>'
grape (0.10.1) lib/grape/endpoint.rb:47:in `block in generate_api_method'
grape (0.10.1) lib/grape/endpoint.rb:247:in `run'
grape (0.10.1) lib/grape/endpoint.rb:195:in `block in call!'
grape (0.10.1) lib/grape/middleware/base.rb:24:in `call!'
grape (0.10.1) lib/grape/middleware/base.rb:18:in `call'
grape (0.10.1) lib/grape/middleware/base.rb:24:in `call!'
grape (0.10.1) lib/grape/middleware/base.rb:18:in `call'
grape (0.10.1) lib/grape/middleware/base.rb:24:in `call!'
grape (0.10.1) lib/grape/middleware/base.rb:18:in `call'
grape (0.10.1) lib/grape/middleware/error.rb:27:in `block in call!'
grape (0.10.1) lib/grape/middleware/error.rb:26:in `call!'
grape (0.10.1) lib/grape/middleware/base.rb:18:in `call'
rack (1.6.0) lib/rack/head.rb:13:in `call'
rack (1.6.0) lib/rack/builder.rb:153:in `call'
grape (0.10.1) lib/grape/endpoint.rb:196:in `call!'
grape (0.10.1) lib/grape/endpoint.rb:184:in `call'
rack-mount (0.8.3) lib/rack/mount/route_set.rb:152:in `block in call'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:96:in `block in recognize'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:75:in `optimized_each'
rack-mount (0.8.3) lib/rack/mount/code_generation.rb:95:in `recognize'
rack-mount (0.8.3) lib/rack/mount/route_set.rb:141:in `call'
grape (0.10.1) lib/grape/api.rb:102:in `call'
grape (0.10.1) lib/grape/api.rb:33:in `call!'
grape (0.10.1) lib/grape/api.rb:29:in `call'
actionpack (4.2.0) lib/action_dispatch/routing/mapper.rb:51:in `serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:802:in `call'
omniauth (1.2.2) lib/omniauth/strategy.rb:186:in `call!'
omniauth (1.2.2) lib/omniauth/strategy.rb:164:in `call'
omniauth (1.2.2) lib/omniauth/strategy.rb:186:in `call!'
omniauth (1.2.2) lib/omniauth/strategy.rb:164:in `call'
omniauth (1.2.2) lib/omniauth/strategy.rb:186:in `call!'
omniauth (1.2.2) lib/omniauth/strategy.rb:164:in `call'
omniauth (1.2.2) lib/omniauth/strategy.rb:186:in `call!'
omniauth (1.2.2) lib/omniauth/strategy.rb:164:in `call'
omniauth (1.2.2) lib/omniauth/builder.rb:59:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `call'
rack (1.6.0) lib/rack/etag.rb:24:in `call'
rack (1.6.0) lib/rack/conditionalget.rb:25:in `call'
rack (1.6.0) lib/rack/head.rb:13:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/flash.rb:260:in `call'
rack (1.6.0) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.0) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.0) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:647:in `call'
activerecord (4.2.0) lib/active_record/migration.rb:378:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `_run_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_call_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
better_errors (2.1.1) lib/better_errors/middleware.rb:84:in `protected_app_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:79:in `better_errors_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:57:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.0) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.0) lib/rack/runtime.rb:18:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/static.rb:113:in `call'
rack (1.6.0) lib/rack/sendfile.rb:113:in `call'
railties (4.2.0) lib/rails/engine.rb:518:in `call'
railties (4.2.0) lib/rails/application.rb:164:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
rack (1.6.0) lib/rack/content_length.rb:15:in `call'
rack (1.6.0) lib/rack/handler/webrick.rb:89:in `service'
/usr/local/var/rbenv/versions/2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
/usr/local/var/rbenv/versions/2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
/usr/local/var/rbenv/versions/2.2.0/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'