12-21-2007
Quote:
Originally Posted by
ktmchen
There are A, B ,C three processes trying to get file lock. A starts to lock file first, then B starts waiting, then C starts waitng. (alarm after ten seconds). Now A releases its lock but C gets file lock instead of B. I don't know how could it happen. Since I use "F_SETLKW", it sholud wait sequentially.
A, B and C are all independent processes. There is no rule that says that he who starts waiting for a lock first is the first to get it, but there is a rule that says only one can have the lock at any time.
It may not seem fair, but it is democratic.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
how can I lock my keyboard while I'm away from the computer without using lock command. What other commands gives me the option to lock keyboard device?
thanks (7 Replies)
Discussion started by: dianayun
7 Replies
2. UNIX for Advanced & Expert Users
I want to know the interrupt passed to a process through 'ulimit'
I am running a process which gets killed when the 'ulimit -t' reaches.
But after killing the process I want to start another process which would
send a message or do some clean up or anything at all.
To do the same I am... (5 Replies)
Discussion started by: mrnuttynuts
5 Replies
3. UNIX for Dummies Questions & Answers
hello all
since a process running in kernel mode cannnot be preempted by any other process what would be the status of Timer interrupt that occurs when the time quantum of a process is elapsed?
thanks (2 Replies)
Discussion started by: compbug
2 Replies
4. Shell Programming and Scripting
Is it possible to sent a ^C interrupt via the command line? For example if I want to tail a log for 10 minutes at a time, kill the tail and then start it again is there a way to go about that? I would imagine there would be some way to do it by finding and killing the PID, but I'm curious if... (2 Replies)
Discussion started by: DeCoTwc
2 Replies
5. UNIX for Advanced & Expert Users
Hi,
i have an rhel box with around 20 %soft every 2 seconds. The box is idle.
How do i start hunting down what's causing this? i believe /proc/interrupts is hardware related, procinfo is basically the same. where else can i look?
thanks,
Marc (5 Replies)
Discussion started by: marcpascual
5 Replies
6. Red Hat
Hello all,
If anyone has time, I have a few questions:
How do I do the following in Linux. We are using Red Hat and Oracle Enterprise Linux, which is based on Red Hat too.
1. How to lock the account after a few (like 3) invalid password attempts?
2. How do you lock a screen after 30... (1 Reply)
Discussion started by: nstarz
1 Replies
7. UNIX for Advanced & Expert Users
I receive the following warning messages on a very new machine which has FreeBSD 8.1 x64 installed on it:
Interrupt storm detected on "irq 20" throttling interrupt source
It is unclear what this means and what its origins are (motherboard? CPU? RAM?).
I can start the desktop and the message is... (4 Replies)
Discussion started by: figaro
4 Replies
8. UNIX for Advanced & Expert Users
Hi all,
I have to test some user priviliges. The goal is to be sure that an unauthorized user can't restart some modules (ssh, mysql etc...).
I'm trying to automate it with a shell script but in same cases I got the syslog broadcast message.
Is there any way to simply get a return code... (3 Replies)
Discussion started by: Dedalus
3 Replies
9. UNIX for Advanced & Expert Users
Hi, all:
Is there any shell command to show which interrupt handler handle which interrupt number in the system?
li,kunlun (5 Replies)
Discussion started by: liklstar
5 Replies
10. Programming
among the below socket programming api's, please let me know which are blocking and non-blocking.
socket
accept
bind
listen
write
read
close (2 Replies)
Discussion started by: VSSajjan
2 Replies
LEARN ABOUT DEBIAN
pthread_rwlock_unlock
pthread_rwlock_unlock(3C) pthread_rwlock_unlock(3C)
NAME
pthread_rwlock_unlock - unlock read-write lock object
SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
The pthread_rwlock_unlock() function is called to release a lock held on the read-write lock object referenced by rwlock. Results are unde-
fined if the read-write lock rwlock is not held by the calling thread.
If this function is called to release a read lock from the read-write lock object and there are other read locks currently held on this
read-write lock object, the read-write lock object remains in the read locked state. If this function releases the calling thread's last
read lock on this read-write lock object, then the calling thread is no longer one of the owners of the object. If this function releases
the last read lock for this read-write lock object, the read-write lock object will be put in the unlocked state with no owners.
If this function is called to release a write lock for this read-write lock object, the read-write lock object will be put in the unlocked
state with no owners.
If the call to the pthread_rwlock_unlock() function results in the read-write lock object becoming unlocked and there are multiple threads
waiting to acquire the read-write lock object for writing, the scheduling policy is used to determine which thread acquires the read-write
lock object for writing. If there are multiple threads waiting to acquire the read-write lock object for reading, the scheduling policy is
used to determine the order in which the waiting threads acquire the read-write lock object for reading. If there are multiple threads
blocked on rwlock for both read locks and write locks, it is unspecified whether the readers acquire the lock first or whether a writer
acquires the lock first.
Results are undefined if any of these functions are called with an uninitialized read-write lock.
If successful, the pthread_rwlock_unlock() function returns 0. Otherwise, an error number is returned to indicate the error.
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
pthread_rwlock_init(3C), pthread_rwlock_rdlock(3C), pthread_rwlock_wrlock(3C), pthread_rwlockattr_init(3C), attributes(5), standards(5)
23 Mar 2005 pthread_rwlock_unlock(3C)