Home > Cannot Lock > Flock

Flock

Contents

I'm wondering if there is a way to implement it Matlab? on a best effort basis…). The lock will not be created that often (i.e. Each client java app accesses the file only through this service.

What is the temperature of the brakes after a typical landing? This way you can even synchronize different parts of the script. #!/bin/bash ( # Wait for lock on /var/lock/.myscript.exclusivelock (fd 200) for 10 seconds flock -x -w 10 200 || exit Second, for an XQuery, keeping the lock during the entire operation would often not be feasible. In general, eXist uses node references to point to real nodes, so node references in $a may become invalid if a different thread is e.g. http://stackoverflow.com/questions/26850724/lock-on-existence-of-file-in-java

Flock

Any advises on how it could be realized otherwise are much appreciated! > > Thank you, > Max Subject: locking file access OR exchanging messages bw Matlab Instances From: Josh Porter For example, if you close a file and then use chmod() to change its permissions, an attacker may be able to move or remove the file between those two steps and Only one process will result in a successful mkdir, all others will fail. In the cflock tag, specify scope="Application".

Other Approaches to LockingOf course, you need not use files to represent locks. Wolfgang Thread view [Exist-open] Lock (exclusive-lock, etc) does anybody have a book, tutorial, or helpful explanation? share|improve this answer answered Oct 9 '08 at 0:20 Drew Stephens 6,95073268 add a comment| up vote 2 down vote When targeting a Debian machine I find the lockfile-progs package to My application serves web pages, and updates the database at the same time to keep track of the event based cache.

This makes it easy to follow the thread of the conversation, and to see what’s already been said before you post your own reply or make a new posting. Variables aren't enough, as each process has its own private variable space, but the filesystem is global to all processes (yes, I know about chroots, namespaces, … special case). To be cross platform, I think you'd have to use file locking on resource.txt and then overwrite the data. Bonuses The check for the existence of the file and the creation of the file if it does not exist are a single operation that is atomic with respect to all other

The resulting Application.totalTickesSold value is now correct. You must never re-open the file, or use any operations that use the filename as a parameter - always use the file descriptor or associated stream. length of time try { inp=new FileInputStream("resource.txt"); } catch(IOException thr) { err=thr; sleep(100); } // or some approp. Please refer to our Privacy Policy or Contact Us for more details You seem to have CSS turned off.

Github

When you attempt to run the program, it can check for the lockfile which and if it exists, it can use ps to see if the process is still running. Seems mkdir is a better solution than set -C; >tempfile if there's any chance you'll be using ksh88 according to the comments there. –Mikel Feb 25 '11 at 2:00 4 Flock It enables any specific number of concurrent processes you want. But did you mean that the renaming (moving) can be triggered to work only if the ORIGIN exists?

Basically I was attempting to provide a different approach to the problem. –frogstarr78 Oct 5 '11 at 17:39 add a comment| up vote 1 down vote I use dtach. $ dtach But the lack of "simpler" solutions in your thread seems to indicate that locking might not be an option. First, each MATLAB session is given an ID. So this may work well with a couple instances of MATLAB, but be warned that it doesn't scale well. -- Josh Feed for this Thread Add to My Watch List What

In this case, every read(2) and write(2) is checked for locking; while this is more thorough than advisory locks, it's also slower. if cannot - try again later <-- handing of a file --> delete('test.lock.lock') % at the end: remove the roadblock It seems to me that these two variants have the same Your locks will still be left behind. Once you create the file atomically, you must alway use the returned file descriptor (or file stream, if created from the file descriptor using routines like fdopen()).

failing to delete the file is not an issue). This one-liner on the top of your script will work: if [ `ps -e | grep -c $(basename $0)` -gt 2 ]; then exit 0; fi Of course, just make sure mona is not in the sudoers file.

more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation

and compare with number. We don't know how long the application wants to keep the result set (it may be stored in a session). procmail also comes with a lockfile tool. However, you sometimes don't want your query to be affected by concurrent nodes updates, so that's why we have those shared-lock, exclusive-lock functions.

This is sometimes a critical issue. –Leliel Jun 2 at 3:24 add a comment| up vote 5 down vote Here is a discussion that relates: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4017593 share|improve this answer answered Feb grep doesn't always find itself in the result of ps! –rubo77 Sep 22 at 21:03 Better use pgrep stackoverflow.com/a/39649227/1069083 –rubo77 Sep 22 at 21:34 add a comment| up vote But mkdir is pretty nice for less demanding use cases IMO. –akostadinov May 13 '14 at 18:03 You can use Bash’es noclobber option with regular files. –Palec Oct 6 share|improve this answer answered Oct 28 '11 at 21:19 Mark Stinson 18713 2 Your script is way too verbose, could've been a lot shorter I think, but overall, yes, you

Or it might not. Another copy is running or manually lock clean up required." exit 1001 # Or work out some sleep_while_execution_lock elsewhere fi } function rmlock { [[ ! -d $__lockdir ]] \ && removing nodes from a resource. Nor can ColdFusion ensure that the order of access to these shared resources is consistent and results in valid data.

By using our services, you agree to our use of cookies.Learn moreGot itMy AccountSearchMapsYouTubePlayNewsGmailDriveCalendarGoogle+TranslatePhotosMoreShoppingWalletFinanceDocsBooksBloggerContactsHangoutsEven more from GoogleSign inHidden fieldsBooksbooks.google.com - Model checking is a branch of software and hardware veri?cation that The attribute of the file is preserved when using "copyfile" command (at least in Linux). Can I hide disabled users in the User Manager? If it does, it removes a job from the data file then deletes the lock-file.

CURRENT_UUID_FROM_LOCKFILE=`cat $LOCKFILE` CURRENT_PID_FROM_LOCKFILE=`cat $LOCKFILE | cut -f 1 -d " "` CURRENT_UUID_FROM_PS=`ps -eo pid,ppid,lstart $CURRENT_PID_FROM_LOCKFILE | tail -1` if [ "$CURRENT_UUID_FROM_LOCKFILE" == "$CURRENT_UUID_FROM_PS" ]; then echo "Script already running with following Reading and writing a shared variableIf you have an application-wide value, such as a counter of the total number of tickets sold, you could have code such as the following on