Thread Synchronization is an important part of Operating System.It is explaining that concurrently-executing threads or processes do not execute specific portions of a program at the same time. If one thread has begun to execute a serialized portion of the program, any other thread trying to execute this portion must wait until the first thread finishes.
Generally the serialize portion of the program is called a s critical section,means if a thread is running in its critical section means no other thread are allowed to enter into their critical section. There are different technique of process/thread synchronization available in C++
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Locking
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Mutex
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Monitor (synchronization)
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Semaphore
Here is a mutex method of thread Synchronization example using C++
//thread synchronization
#include
#include
#include
#include
#include
using namespace std;
pthread_mutex_t m=PTHREAD_MUTEX_INITIALIZER;
void *writer1(void *fd)
{
int f=*(int*)fd;
char *string1=new char[200];
pthread_mutex_lock(&m);
cout<<"\n enter 1st thread items to write in file";
gets(string1);
for(int i=0;i<=strlen(string1);i++)
{
write(f,&string1[i],1);
sleep(1);
}
pthread_mutex_unlock(&m);
}
void *writer2(void *fd)
{
int f=*(int*)fd;
char *string2=new char[200];
pthread_mutex_lock(&m);
cout<<"\n enter enter second thread items to write in file";
gets(string2);
for(int i=0;i<=strlen(string2);i++)
{
write(f,&string2[i],1);
sleep(1);
}
pthread_mutex_unlock(&m);
}
main()
{
pthread_t t1,t2;
int fd=open("file.txt",O_CREAT|O_RDWR|O_APPEND);
pthread_create(&t1,0,writer1,&fd);
pthread_create(&t2,0,writer2,&fd);
pthread_join(t1,0);
pthread_join(t2,0);
}
About SourceCode
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pthread_create(),pthread_join() are two library function to create thread and waiting for thread simultaneously.
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pthread_mutex_t is used to declare mutex variable.
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PTHREAD_MUTEX_INITIALIZER is used to initialize a static mutex.
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Here we are doing file locking using pthread_mutex_lock(pthread_mutex_t*) function and unlocking using pthread_mutex_unlock(pthread_mutex_t*) function.
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The primary objective of this source code is to write into a file in a synchronization way.
Application Area
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Banking Transaction
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Database System
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Web Servers
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Designing Multithreading OS
Mohtashim
Latest posts by Mohtashim (see all)
- Syncronization in threads using POSIX thread - October 12, 2012
Read about these topics(mutex, semaphore) under OS in our college days,
but no one ever gave any programming example.
Thank you