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Full Discussion: What Unix do with unused shared memory?
Top Forums Programming What Unix do with unused shared memory? Post 302458268 by pronetin on Thursday 30th of September 2010 09:06:13 AM
Old 09-30-2010
What Unix do with unused shared memory?
Hello,

When creating shared memory in C, should be remove shared memory with shmctl function when don't need it. If it didn't remove, occupied shared memory stay and remain.

If we create shared memory repeatedly without removing unusable shared memory, /dev/shm will full.

Does Unix or Linux distributions do action to them? For example if a shared memory has 0 shm_nattch and wasn't used in long time, remove them.
 

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LEARN ABOUT HPUX

shm_unlink

shm_unlink(2)							System Calls Manual						     shm_unlink(2)

NAME

       shm_unlink - unlink a shared memory object

SYNOPSIS

DESCRIPTION

       The  system  call  removes  the	name of the shared memory object named by the string pointed to by name.  If one or more references to the
       shared memory object exists when the object is unlinked, the name will be removed before returns, but the removal of the memory object con-
       tents will be postponed until all open and map references to the shared memory object have been removed.

RETURN VALUE

       returns the following values:

	      Successful completion.

	      Failure,
		   is set to indicate the error.

ERRORS

       If fails, is set to one of the following values:

	      [EACCES]	     Permission to unlink the named shared memory object is denied.

	      [ENAMETOOLONG] The  length of the name string exceeds or the length of a (pathname) component of the name string exceeds while is in
			     effect.

	      [ENOENT]	     The named shared memory object does not exist.

	      [ENOSYS]	     is not supported by the implementation.

SEE ALSO

       shm_open(2), close(2), mmap(2), munmap(2), privileges(5).

STANDARDS CONFORMANCE

																     shm_unlink(2)
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