Linux C Programming Multithreading basic article

Linux C Programming Multithreading basic article

Preface: Because of the design and implementation of the Linux network intrusion detection system want to use multi-threading, so want to learn the Linux C programming multithreading knowledge

Note: Because the Pthraed library is not the default Linux system library, so in the multi-threaded development, need to add the header file # # <pthread.h>, compile with parameters-lpthread; GCC thread.c-o Thread-lpthread.

Processes and Threads:

1. Process is the basic unit of program execution, resource allocation, each process has its own data segment, code snippet, stack segment, there is a more complex context switch during process switching

2. A thread is a process-independent running route, which is the smallest unit of processor scheduling, also known as a lightweight process, that can access the memory space of the process, and share memory space, code, and resources with other threads of the process.

3. Thread-related execution state and storage variables are placed in the inline control table, a process can have multiple threads, multiple thread control tables and stack registers, and a user address space is shared
   

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Important noun:

Thread identity: The thread ID, the process ID is unique throughout the system, the thread ID is valid only in the environment of the owning process, the thread identity is represented by the data structure pthread_t, the pthread_t cannot be processed as an integer, and Linux uses unsigned long-shaped numbers to represent pthread_t.

Important functions:

1. Pthread_self ()
   

Function prototype: pthread_t phtread_self (void)

Parameters: None

return value: (in progress) thread ID of the calling thread

2. Pthread_equal ()

Function prototype: int pthread_equal (pthread_t tidone,pthread_t tidtwo)

Parameters: 2 Thread ID

Return value: Equals returns a value other than 0, otherwise 0

#include <stdio.h> #include <stdlib.h> #include <pthread.h>int main () {pthread_t thisid;   Thisid = Pthread_self ();   printf ("Current Thread ID =%lu.\n", thisid);   if (Pthread_equal (Thisid,pthread_self ())) {printf ("yes,equal\n");   }else{printf ("No,not equal\n");} return 0;}

3. Create a thread

• The entry point to invoke the thread function

• Using the function pthread_create (), after creating the thread, start running the related thread function

function Pthread_create ()

function prototypes: int pthread_create (pthread_t *thread,pthread_attr_t *attr,void* (*start_routine) (void *), void *arg);

Parameters: thread identity; attr thread property setting, usually set to Null;start_routine: The starting address of a thread function, is a pointer to void as a function pointer to a parameter and a return value; ARG: The function passed to Start_runtine

Return value: Successfully returned 0, failed to return failure code

Pthread_create (&tid,null,thrd_func,null)

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Linux C Programming Multithreading basic article