The default log level should be WARN which will write a message to the log file only if a request has been blocked.
默认的日志记录级别应该是WARN，它只在已经阻止了请求的情况下在日志文件中写消息。
2
While blocked, the managed task continues to hold any Shared resources it acquired during the course of its dispatch (for example, storage resources, task-level resources, and mutex locks).