Communication mode between processes

The Conduit ： It is a half duplex mode , Data flows in one direction , Can only be used between related processes . It is kernel based , You can use it as a kernel buffer . Four copies are required to exchange data with the kernel in user space , User space —> kernel , kernel —> Memory , Memory —> kernel , kernel —> User space , Why copy to the kernel here ？ Because the data is executed in memory . The data in the pipeline can only be read 1 Time , After reading, the buffer does not exist , It can only carry unformatted byte streams .
name pipes ： Similar to pipes , But it allows unrelated processes to access （ All processes can access ）, The name of the named pipe corresponds to the disk inode .
Message queue ： Message linked list , Is a series of message linked lists stored in the kernel , Data exchange also needs to be done 4 Second copy . Its advantage is that you can specify a specific message type for each message , The receiver may not get the information in the order of the queue .
Shared memory ： Map a memory block that can be accessed by other processes , Memory sharing , Created by a process , Multiple process access . It only needs to be copied three times to transfer data , That's user space —> Memory —> User space .
Semaphore ： Control the access of multiple processes to shared resources , It can be used to synchronize processes or threads .
The signal ： It's a complicated way of communication , Notify the receiving process that an event has occurred .
Socket Socket： Socket Socket Is the cornerstone of communication , It is based on TCP/IP Basic operation unit of network communication of protocol , It is an abstract representation of the endpoint in the process of network communication , Contains five types of information for network communication ： Connection use protocol 、 Local IP Address 、 Protocol port of local process 、 long-range IP Address 、 The protocol port of the remote process .