[WIP] Concurrent read large file

[LuQQiu]

Prerequisite: Alluxio REST API return file size from list operation (preferred) or get file status operation
Current issue: Alluxio REST API perf may bottlenecked by Alluxio server thread pool size

[LuQQiu]

have an assumption that Alluxio server is bottlenecked (only have limited threads executing the I/O tasks)
Alluxio http server workergroup is EventLoopGroup workerGroup = new NioEventLoopGroup(); This line creates a group with a default number of threads for handling the actual I/O work (reading and writing data). The default number of threads is 2 * number of available processors, as per Netty’s documentation.
DEFAULT_EVENT_LOOP_THREADS = Math.max(1, SystemPropertyUtil.getInt(
“io.netty.eventLoopThreads”, NettyRuntime.availableProcessors() * 2));
available processors may not show actual value in container env from Shawn and my experience

Alluxio/alluxio#17021