10 More Discussions You Might Find Interesting
1. UNIX for Beginners Questions & Answers
I was asked to add this piece of code to a c program which I will execute through the shell:
for(long i = 0; i < NITER; i++)
{ sem_wait( &sema);
count++;
sem_post( &sema); }
I didn't get it, which is the critical section ? if it's "count++" how would a thread wake up in order to enter it... (1 Reply)
Discussion started by: uniran
1 Replies
2. Solaris
Can anyone tell me abt the Semaphore concept and what is semaphore???
is semaphore id is associated in terms as in resources like semaphore id 1 indicates cpu share unit is given and semaphore id 2 will indicate abt the memore or semaphore id 3 will tell us the i/o components (1 Reply)
Discussion started by: aarjun07
1 Replies
3. Shell Programming and Scripting
Control two exclusively shared resources(semaphore). The two resources are two files. The producer will write even numbers to one file, and odd numbers to another one. The consumer respectively reads from each file until it gets 5 even numbers and 5 odd numbers.
Can any one help me with the... (0 Replies)
Discussion started by: gokult
0 Replies
4. Programming
In my server code there is a thread per client...
The server call accept() and after that start the thread.
So there is a thread for client that save in RAM the client's message, that will be send to other clients.
Now in RAM I have created a shared memory in which thread read and write(save)... (2 Replies)
Discussion started by: italian_boy
2 Replies
5. UNIX for Dummies Questions & Answers
what is semaphore? can any body explain it in a more simple way than the manual ??
replies appreciated
Regards
raguram R (7 Replies)
Discussion started by: raguramtgr
7 Replies
6. Shell Programming and Scripting
Hi,
I am looking to use a semaphore for the first time in one of my scripts. I am just wondering if there are any simple examples or tutorials around?
I am a beginner so the simpler the better :)
Thanks
-Jaken (2 Replies)
Discussion started by: Jaken
2 Replies
7. UNIX for Advanced & Expert Users
Hi All,
I am going through the semaphore concept and have a doubt regarding the same and hope to get a resolution here.
I have a file which has a number of records.
I want to write an application (in C) which will be able to do concurrent read/write on these records.
Of what I have... (8 Replies)
Discussion started by: maverix
8 Replies
8. Programming
I'm running one multithreaded application, in that one of my thread
is waiting infinitely in a semphore. Is there a way to determine, in
which semaphore the particular thread is waiting and which thread(s)
is holding the semaphore. (5 Replies)
Discussion started by: ptprabu
5 Replies
9. UNIX for Dummies Questions & Answers
Hi,
I'm new to UNIX.
I need to know what's a semaphore
Do reply.
Thanks
VJ (3 Replies)
Discussion started by: vjsony
3 Replies
10. UNIX for Dummies Questions & Answers
hi, is there any command where we can monitor semaphores? (1 Reply)
Discussion started by: yls177
1 Replies
sem_close(2) System Calls Manual sem_close(2)
NAME
sem_close - close a named POSIX semaphore
SYNOPSIS
DESCRIPTION
is used to close a named semaphore. A successful call to will do the following: Remove the process's descriptor for the semaphore refer-
enced by the specified structure sem. Remove the semaphore referenced by the specified structure sem, if the semaphore is marked for
removal by a call to and there are no other descriptors referencing this semaphore.
When the process's descriptor for the semaphore referenced by sem is removed, subsequent use of this semaphore by this process will fail.
Descriptors for named semaphores are also removed by processes on exit. Calling does not affect other processes referencing the same sema-
phore.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
EXAMPLES
The following call to will close a named semaphore referred to by sem by removing the process's descriptor to the semaphore and removing
the semaphore if it is marked for removal by a previous and there are no descriptors referencing it.
RETURN VALUE
If the semaphore was closed and the descriptors referencing it were removed, returns 0 to the caller.
If the semaphore could not be closed, the call returns -1 and sets to indicate the error.
ERRORS
fails and does not perform the requested operation if the following condition is encountered:
[EINVAL] The argument sem is not a valid named semaphore.
WARNINGS
A single call will make the semaphore unusable by the process no matter how many times that process had called for the same semaphore.
Subsequent calls to by the same process for the same semaphore will result in an undefined behavior.
SEE ALSO
sem_init(2), sem_open(2), sem_unlink(2), <semaphore.h>.
STANDARDS CONFORMANCE
sem_close(2)