Java Startup Params

Basic Format Run java -help to see the basic format and options 1 2 3 4 5 6 7 8 [root@localhost ~]# java -help Usage: java [-options] class [args...] (execute class) or java [-options] -jar jarfile [args...] (execute jar file) Startup options are omitted [-options]: options [-options]: options [args...] : Passes a parameter to the main method Standard options -help / -? : output help information -version : output version information -classpath / -cp: class search path for directories and zip/jar files .

JavaNIO and Zero Copy

Zero-copy in the Linux operating system Let’s start with the general I/O process of Linux This is a procedure that reads from a disk file and writes to it via socket, and the corresponding system call is as follows. 1 2 read(file, tmp_buf, len); write(socket, tmp_buf, len); The program uses the read() system call to change the system from user state to kernel state, and the data from the disk is read into the kernel buffer by means of DMA (Direct memory access).