File locking question

Hello,
We're considering using java to write in a new(to us) file system, OCFS2. However, this file system lacks certain features expected for file locking. Our app does not use java.nio.* that much, but it does use it. My question is what exact standards does the JVM require for file locking? Or is it ad hoc?
If its ad hoc, what sys/func calls are required for locking?
Thanks,

The docs are rather specific that all of the functionality for FileLock is platform dependent.
So you should test it.

Similar Messages

Question regarding file locking...

Hi all--
Here's the essential question...
If I have a shared file across the network that will be subjected to multiple accesses from multiple clients. Most just need to read it, but some will occassionally need to write to it. If my client application obtains a lock on the file using FileLock myLock = myFileInputStream.getChannel().tryLock(), will other clients still be able to read the file?
in other words, is the file lock obtained a "read-only" lock, preventing writing but allowing reading? or will other client's be unable to read the file when someone has a FileLock on it?
Right now we use an excel spreadsheet. It's an utterly terrible solution, but what's good about the spreadsheet is that everyone can read it, but if someone has accessed it to begin with, you only have read-only access to it. Which is good...
can I do the same thing using Java file-lock? Allowing the first client who accesses it to obtain a full-permisions lock but subsequent clients only are able to obtain read-only access?
Thanks for the help!

The docs are rather specific that all of the functionality for FileLock is platform dependent.
So you should test it.

File lock() method problem

I know this may be a common question, but can someone explain why this code:
import java.io.*;
import java.nio.channels.*;
import java.util.*;
public class TestFileLock
     private static File file;
     private static RandomAccessFile fileRandom;
     private static FileChannel fileChannel;
     private static FileLock fileLock;
     private static String process;
     public static void main(String[] args)
          process = args[0];
          try
               file = new File("/home/fauxn/work/blast/java/java_blast/test.log");
               //fileWriter = new FileWriter(file, true);
               fileRandom = new RandomAccessFile(file, "rw");
               fileChannel = fileRandom.getChannel();
               for(int i =0; i < 1000; i++)
                    writeLogFile(process + ": happy days\n");
          catch(Exception exception)
               System.out.println(exception.getMessage());
               exception.printStackTrace();
     * Method lockes the logFile and then append the string to the file and unlocks the file.
     * @author Noel Faux.
     * @param s The string to be written to be appended to the file.
     private static void writeLogFile(String s) throws IOException
     System.out.println(process + ": trying to lock the log file");
     fileLock = fileChannel.tryLock();
     while(fileLock == null)
               System.out.println(s + ": waiting!!!!");
               fileLock = fileChannel.tryLock();
     System.out.println(s + ": logfile locked");
          fileRandom.seek(fileRandom.length());
     fileRandom.write(s.getBytes());
          fileLock.release();
          System.out.println(s + ": logfile unlocked");
produces this error:
Invalid argument
java.io.IOException: Invalid argument
at sun.nio.ch.FileChannelImpl.lock0(Native Method)
at sun.nio.ch.FileChannelImpl.tryLock(FileChannelImpl.java:528)
at java.nio.channels.FileChannel.tryLock(FileChannel.java:967)
at TestFileLock.writeLogFile(TestFileLock.java:43)
at TestFileLock.main(TestFileLock.java:23)
on a intel linux box, java 1.4 and this code works fine:
import java.io.*;
import java.nio.channels.*;
import java.util.*;
public class TestFileLock
     private static File file;
     private static RandomAccessFile fileRandom;
     private static FileChannel fileChannel;
     private static FileLock fileLock;
     private static String process;
     public static void main(String[] args)
          process = args[0];
          try
               file = new File("/home/fauxn/work/blast/java/java_blast/test.log");
               //fileWriter = new FileWriter(file, true);
               fileRandom = new RandomAccessFile(file, "rw");
               fileChannel = fileRandom.getChannel();
               for(int i =0; i < 1000; i++)
                    writeLogFile(process + ": happy days\n");
          catch(Exception exception)
               System.out.println(exception.getMessage());
               exception.printStackTrace();
     * Method lockes the logFile and then append the string to
* the file and unlocks the file.
     private static void writeLogFile(String s) throws IOException
     System.out.println(process + ": trying to lock the log file");
     fileLock = fileChannel.tryLock(0, fileRandom.length(), false);
     while(fileLock == null)
               System.out.println(s + ": waiting!!!!");
               fileLock = fileChannel.tryLock(0, fileRandom.length(), false);
     System.out.println(s + ": logfile locked");
     fileRandom.seek(fileRandom.length());
     fileRandom.write(s.getBytes());
     fileLock.release();
     System.out.println(s + ": logfile unlocked");
Any suggestions welcome, or is this a bug????
Thanks in advance :)

Its a known bug. The default tryLock() method calls the parametered
tryLock method as follows
tryLock(0,Long.MAX_VALUE,false);unfortunately under linux the parameter Long.MAX_VALUE is too big for
the underlying OS file locking. This causes the IOException to be thrown
It has been fixed in version 1.4.1 i believe.
For more info
http://developer.java.sun.com/developer/bugParade/bugs/4532474.html
matfud

File locked message when saving a file with Photoshop

We've been seeing a problem with several users that is hard to reproduce. Every once in a while when they try to save a file in Photoshop on the server they get a dialogue saying 'the file is locked, use Finder info to unlock the file'.
This file is located on the server and the problem only happens when doing a 'Save', not with a 'Save as'. The server is running 10.5.5 and the clients are 10.4.11. This is happening with Photoshop versions CS1, 2 and 3. It also happend with Illustrator CS3 once.
We've been experimenting with different scenario's using different ACL's and POSIX settings. Also, when the client reboots their machine the exact same 'Save' actions works again.

I've been receiving complaints about a similar issue over the past few weeks, except using Quark and Excel. I wonder if it's related to the 10.5.5 update. Are you sure you didn't get the version numbers reversed in your post? We're having the issue with 10.4.11 SERVER and 10.5.5. CLIENTS.
It's a file locking issue, so you probably won't fix it by changing the ACLs or POSIX permissions. The server thinks a different process still has the file open, so it's preventing you from changing the file. "Save As" works because it creates a new file.
You can probably eject & reconnect the volume from the client instead of fully rebooting.
The question is what's keeping the file open. You can run:
sudo lsof | grep <filename>
... in Terminal to see whether a given Mac has the file open. If the server comes back with a response to that command (don't worry what it says - you just want to see if anything comes back), then you know that the file is locked.
Next, go to each client that could have the file open and run the same command. If none of them have it open, you're probably looking at the same glitch that I've been. The server thinks a file is open but none of the clients do.

File Locking in XI-

Hi all,
   I need to implement file locking technology for all of my interfcaes.Could anyone explain me the basics and detailed procdure for this?
Thanks
Rajesh

Hi Rajesh,
Look into the Note 821267 (3 question).
Unfortunately, the J2EE 1.3 technology the File Adapter is built upon does not support file locking. This limitation affects the File Adapter's operation. Depending on whether the JRE implementation for the operating system under which the adapter runs uses mandatory file locking or advisory file locking, opening a file that is currently being written to by another process will fail or not.
If opening the file fails, no problem exists and the adapter will try to open the file each poll interval until it succeeds.
However, if opening the file is not prevented by the operating system, the adapter starts to process the file although it is still being modified. Since XI 3.0 SP11 / PI 7.0 there is a parameter named "Msecs to Wait Before Modification Check" in the advanced settings of the File Sender channel configuration to work around this issue. This setting causes the File Adapter to wait a certain time after reading, but before sending a file to the Adapter
Engine. If the file has been modified (which is basically determined by comparing the size of the read data with the current file size of the input file) after the configured interval has elapsed, the adapter aborts the processing of the file and tries to process the file again after the retry interval has elapsed.
If this option is not available for the settings you would like to use, the following algorithm (to be implemented in your application) may be used to ensure that the File Adapter only processes completely written files:
-     Create the file using an extension, which does not get processed by the File Adapter, e.g., ".tmp"
-     Write the file content
-     Rename the file to its final name, so the File Adapter will notice its existence and pick it up
Source: SAP Note
Regards
San

WAFS/WAAS File Locking

I have run into an issue that i believe is file server related however i just want to run it by the board for clarification.
A remote site was recently converted from a standalone server site to one that is supported via WAFS/WAAS 4.0.11 installed on a 512 WAE w/ 2GB of Ram acting as wafs edge. The core is a 612 w/ 4GB of ram.
All user home folders reside across the WAN in the data center on a NetApp NAS SAN hosting the home folder natively (there is no windows server involved).
The issue is with file locking. Periodically, when a user opens a file on the server that is already been opened they are not getting any indication that the file is in use. Once they go to save the file they are told by the system that they cannot save the file using the same filename since it is being modified.
From reading the docs on WAFS/WAAS this looks like it is a problem with the OpLocks coming from the NetApp NAS and nothing to do with WAFS since WAFS/WAAS doesn't act on file locking requests, only passing them through to the file server.
Are my assumptions correct in this regard? Could WAFS be interferring some how with this communication and causing the file locking information being received from the NetApp NAS not to be correctly sent to the client?
Any way for me to debug this besides a packet capture? Any show commands that could indicate an issue? or logs?
TIA
Mike Louis

Zach,
Part of the problem appears to be packet loss of the 4050 messages. We have created a class-map to match 4050 traffic and the connectivity directive in the WAE. Hopefully this will solve some of the intermittent file locking issues we are having.
However, i had some other questions after poking around in the /expert mode of the WAE.
1. When changing the WAFS connectivity bandwidth statement the CM states that the device Edge Component must be restarted. Is there a command that will allow me to do this without rebooting the box? Can i just remove the device from the Core - Edge group and then reassign it to restart the process?
2. Under the expert mode in 4.0.11 i noticed this value:
LockManager MBean Attributes:
Name Type Access Value
MaxGrantedLock int RO 10
MaxPendingLock int RO 0
What does MaxGrantedLock mean here? Will it not grant more than 10 locks at one time?
I have about 60 simultaneous users on file shares at any one time and they are intermittently not receiving the "file in use" statement from the server. Could this be part of the problem?
Thanks in advance
Mike

File locking issue

hi ,
I use a java applet for ftp images upload using a third party ftp API library (edtftpj).
i run my applet from browser but I'm experiencing a strange issue :
-i upload a file & leave the browser opened.
-i then open this same file with gimp or photo-shop & get 'file in use' error.
-if i close browser & try opening file ,the file is opened correctly.
I investigated the issue more thoroughly and here are my conclusions :
1) First i made sure to close all File's streams in the applet.so I'm sure i eliminated this issue of forgotten opened file streams .
2) also i made sure to close all network connections that might be holding the File lock.
It's clear that another process is still locking the File & preventing access to it.
i used a win32 program (procExp) to monitor active processes . it turned out that javaw.exe is the process that use the File. i was convinced of this fact with a simple experiment : if i destroy the applet (closing applet's browser window -not necessarily all browser instances-) then in this case the file lock is released and i can access and delete File correctly.
my questions :
-How to instruct javaw.exe to release the File lock ? (is that possible at all to do ?)
-is it a bug in JVM ? (i'm using jdk1.4.2)
-or is it an OS centric issue related to windows only ?
i would appreciate your ideas about this problem .
thanks.

Exactly, and I've been aware of all that since about 1997. I don't know whether that was supposed to answer my question to you as the OP but it doesn't.
Sadly I misread your second-last post to say that you are using Thread.stop(), which you're not, so that explains some of the confusion. But I don't understand why you say Thread.interrupt() doesn't release the resources. It isn't supposed to. It doesn't do anything except set a flag and cause your thread to throw an InterruptedException if it's calling Object.wait(), Thread.sleep(), or certain I/O routines. It's up to your thread to react appropriately, and/or to call Thread.isInterrupted at appropriate intervals.
So Thread.interrupt() (a) provides the boolean flag you need and (b) also interrupts your thread under some circumstances. So it is definitely the solution you should be using: call Thread.interrupt() to tell the thread to exit, and call Thread.isInterrupted() in the thread itself to know whether to do so.

File Locking on solaris with C++ fstream

Hi Guys,
I have a problem with file locking on Solaris 5.6 with fstream. All of the file locking methods I know act on a file descriptor (flock,lockf, fcntl). In this particular scenario I got to use any C++ streams.
I'm particularly concerned with fstream filebuf flags. In Window NT Iam using filebuf::sh_none falg to prevent another process or thread from accessing the same file till I explicitly close the file.
I read some where, we can use filebuf::openprot on solaris. But If I use this openprot my Compiler(Work Shop 5.0) giving compilation error
Error: openprot is not a member of std::basic_filebuf<char, std::char_traits<<char>>.
So, if somebody can provide me with some other options about this it would be very helpful.
Any help greatly appreciated
Thanks

Sorry to be playing Twenty Questions, but I see
a problem with Solaris support. potentally. What
version of Solaris are you using? You might need
to use a later version of FD to avoid potential
bugs interacting with the OS.

File locking as in perl

Hi,
could somebody please give a one-two-liner about how to do file locking in Java, to achieve a similar result to perl below:
sysopen(INDEX, $fileName, O_RDONLY);#these 2 lines are especially needed
flock(LINDEX, LOCK_SH);
sysopen(INDEX2, $fileName2, O_WRONLY|O_TRUNC);
flock(LINDEX, LOCK_EX);#this one would be nice to have too
The flock calls are only valid in UNIX, for perl. I wonder how it is done in Java.
P.S.
W/o any locking, does Windows lock all opened files by default?
W/o any locking, does UNIX NOT lock all opened files by default?
Thanks,
r

I modified the class a little. But i still have some questions.
1) Most importantly, locking files using this class would require that all file opening operations are handled by this class, right? So if some other program opens the file, God forbid for writing, w/o referring to this class, the file if gone.
2) Do methods open and close need to be static as well? If there is only one instance of a class, and several threads call synchronized method, does it all go to the same place? Conversely, if that method is not synchronized, then it could be running in several RAM locations?
3) While this solution is limited, it is a step forward. However, i would really appreciate some tips on using
a) java.nio.channels.FileLock
perhaps as relates to
protected Object lock in java.io.Reader
b) public boolean setReadOnly() in java.io.File.
In a) (which is mostly for exlusive locks, i guess), i pretty much don't understand anything. In b) (which is an equivalent of a shared lock), i don't get how to set the file back to writable, which is mentioned in API:
"After invoking this method the file or directory is guaranteed not to change until it is either deleted or marked to allow write access."
Thanks in advance,
r
----------------Modified partial solution---------------
class LockedFile {
final File name;
private FileReader fr = null;
private BufferedReader bufferedReader = null;
LockedFile(File n) {
     name=n;
public synchronized void open() throws IOException {
     while (fr!=null) {
          wait();
     fr = new FileReader(name);
     bufferedReader = new BufferedReader(fileReader);
public synchronized void close() throws IOException {
     close(in);
     fr = null;
     notifyAll();
public int read() {
     return fr.read();
public String readLine() {
     return bufferedReader.readLine();
}

File locking and shell script

Hi,
with Mac OS X is there a file locking system to prevent file to be copyied or move to a folder B before they are completely copyied in folder A ?
Regards

The files in folder A are created by a program like
Pitstop
My question was : what can happen if a file in folder
A is not complitely created and the shell script
attempt to copy it ?
In general, if the shell script attempts to copy a file before the creator is finished writing to it, the shell script will copy the part of the file that's already present, so the copy will be incomplete. The creating application can prevent that (by writing to a temporary file and changing the name of the file only after it's finished writing, or by making the file readable only after it's done), but that's up to the application.

XSL File locked after error

Hi,
I've tried to modify a XSL File that I created with Forms Builder. It's all because I want to add some functionality.
Now here is my problem. Because the XSL is not perfect at the moment, it produces some errors while parsing. Unfortunately after that the file is locked on the file system so that I can't change it anymore. So debugging is a little bit hard because I know the error but can't fix it.
Finally my question: Is there a possibility to unlock the file so that I can edit it again (without restart)?

Hi,
Normal PCD objects can be unlocked through System admin->Monitoring, not sure if this applies to XSL files as well.
If the file is locked by a process and cannot be released, you could process explorer to search for the file handle and delete the "file lock" the process has.
See
http://www.microsoft.com/technet/sysinternals/utilities/ProcessExplorer.mspx
dagfinn

File lock timeout length

When a user opens a document and a file lock timeout period is set on it in the database, how does SharePoint 2013 determine the length of time to make the lock period? This is an issue when a user has their system crash, but the file lock from their
original session remains open until the file lock timeout expires.
I already know there's a non-supported way to fix this in the database, but Microsoft's official recommendation is to wait "10 minutes", yet I see on most files the lock timeout is set to hours in the future. This causes users an unbelievable
amount of frustration to either wait multiple hours, or save a copy and merge changes later. Is there a fix to lower the file lock timeout value to something more reasonable? Why was this designed so terribly?

It is actually depending on your session timeout settings.
This prevents other users to modify \ overwrite it.
Check if below can answer some more question of yours
Office has to be continuing to extend that short term lock. You may check if this is the issue:
http://paulliebrand.com/2008/01/04/document-is-locked-for-editing/ or check this
http://paulliebrand.com/2010/04/12/document-is-locked-for-editing-part-2/
If this helped you resolve your issue, please mark it Answered

I got new hard driver for my MacBook I don't have the cd but I do have flash drive that has the software I need help because when I turn on my laptop it shows me a file with question mark how can I install the software from the flash driver?

I got new hard driver for my MacBook I don't have the cd but I do have flash drive that has the software I need help because when I turn on my laptop it shows me a file with question mark how can I install the software from the flash driver?

Hold down the Option key while you boot your Mac. Then, it should show you a selection of devices. Click your flash drive and it will boot from that.

File locking with OSX Server & Microsoft Word

We have a small office LAN based on a Airport Extreme bases station. Periodically Microsoft Word reports a break in connection to the shared folder where we store documents to get disconnected. When that happens and the user reconnects to the share, the user gets the file read-only message for the Word document that was open at the time.
I have found that in order to clear the read-only flag, I have to restart the server and open the Word file on the server with the ID of the user who was editing the file on the remote computer. Only that seems to clear the file locking that causes the file to be read-only.
I cannot figure out a less drastic way to release the lock file. I don't see any hidden temp files in the same folder as the document that is locked for editing found by ls -a or in the root direction of the shared folder in the .TemporaryItems/folders.<UID> that seems to be holding the lock.
I have run chflags nouchg <Word file> from Terminal, but that seems to have no effect either. I also used xattr to see if there were any locks held that way, but I don't see anything that way either.
File sharing to Macs only, which are configured just to use AFP through OSX Server.
Does anyone understand how the file locks of Word documents can be released directly with out restarting the server?
I should add that the underlying problems seems to be WiFi related. The behavior is that the WiFi connection seems to break long enough that the shared volumes disconnects. Outlook also causes a break. This behavior seems to have started with 10.9 and the purchase of new Retina Display MacBook Pros. I turned off AppNap on the Office applications but that is not clearly helpful. I also have been told the problem seems more likely to occur when Word is open in the background and another program like Outlook is in the foreground.
Any suggestions appreciated.

Apple write an operating system and also produce file sharing software as part of that to be used as a file server. Apple provide documentation for third-party software developers on how they should write software to work with Apple's software and also give those developers early access to new versions so those third-party developers can test and if needed make adjustments and issue updates to cope with any Apple changes.
Some third-party developers are good at dealing with this, some are bad, and some totally ignore what Apple does and give the impression they don't care if their product works properly or not. I think we can all judge where Microsoft sits.
It appears Microsoft have never paid any attention in particular to how Apple expect file-locking to be handled when accessing files on a Mac server. There have been problems for years and years and years with Office. Two other problems I have seen which seem different to yours but probably related are -
With Office documents it is supposed to be possible for more than one person to edit the same file at the same time, consider it a miracle if this actually works
With Office in particular Word, there is an auto-save function, unfortunately the way this seems to be implemented it seems that Word creates a new temporary file each time it auto-saves the document and keeps all the previous temporary files open still, this eventually means potentially over a hundred temporary files are open - just for one Word document and you can then hit a limit on the total number of files you are allowed to have open at the same time. At this point further auto-saves fail, and you also encounter great difficulty doing a real full save of the document.
I do not hold Apple completely blameless over this issue, it is likely their file-locking implementations change too often, and have inadequate documentation, however even considering this a company the size of Microsoft with the amount of sales (and profit) they derive from Office for the Mac has no excuses at all for failing to put the effort in to resolve any such clearly critical problems.
We could go on and on about other areas where Microsoft don't play by the (software) rules. Even in Windows Office does not obey the standard print dialog rules Microsoft specified themselves!
Unfortunately not only is Office for Mac upgraded infrequently, but even when new paid for upgrades are released Microsoft have a history of still not fixing bugs. It goes without saying that a mere free update is even less likely to actually fix a bug, typically such free updates only address security issues. The next version of Office is going to be Office for Mac 2014 see http://www.macworld.com/article/2106643/microsoft-will-release-a-new-version-of- office-for-mac-this-year.html
One area I confidently predict Microsoft not to resolve in Office for Mac 2014 is that fact that Word for Mac still does not support right-to-left languages like Hebrew and Arabic. This is despite the fact that OS X itself has supported this for years and years, and despite the fact other Mac programs support this including the free TextEdit and Pages - both of which can read Word files. Some people may remember that at one point the Israeli Government temporarily banned all Microsoft software over this issue. See http://apple-beta.slashdot.org/story/03/10/15/2215249/israeli-government-suspend s-microsoft-contracts This issue goes back over TEN years!!
I note that Microsoft has now taken their OfficeForMac blog offline, probably due to the weight of criticisms. I would not say it is due to out-right anti-Microsoft hate, that war ended long ago. We just want products that work. I myself do use Microsoft products, even at home - where they are the best solution, so I use Microsoft Media Center for example. Sadly this is now being neglected by Microsoft.

Office 2010 & 2007 - Excel and Access File Locking Out On the Network With Multiple Users

This is also posted in the Office 2010 - IT Pro General Discussions, but was suggested to repost here, since a definitive answer was not found.
Hi,
An issue that's happening is that Excel and Access files are locking on the network. We're currently using Office 2007 and 2010.
Here are some different scenarios that are happening:
When opening the file it is locked out by “User X” which is the person that has the file locked out and no one else can open the file.
When opening the file it is locked out by “User Y” which is NOT the actual person, but is locked out by “User X” and no one else can access the file.
When opening the file it is locked out by “…another user” which is generic and no one else can access the file.
The two more common events are incident 1 and 2 with 3 happening the less common.
This message will continue until the sessions are closed through computer management on the file server.
The file server is running Windows Server 2003.
This does happen on both Windows XP and Windows 7 clients.
This does happen for users using Office 2007 and Office 2010.
There are two sets of Office 2010 Users when it comes to patches. Everyone has the most current patches with Office 2010 SP2 while anyone that has Microsoft Project 2010 is using all the current update before Office 2010 SP2.
All users that are using Office 2007 have all the current patches and service packs.
Another variable is that we have users that will leave a file open on the network for 3+ days and after a while it will lock the file out.
Also we have Shadow Copy that runs daily on the system which I'm not for sure if that impacts anything if a file is opening during that time.
Any ideas on how to mitigate the lock out issues would be appreciated.
Thanks,
Binary Process
Edit November 12, 2013: This issue can occur if and if not another person actually has the file open. If the person doesn't have the file open then there is a hung connection which needs to be disconnected by going to the Computer Management of the File
server.

Hi Binary,
I know that the description of the hotfix does not relate to the issue. The purpose is to install it for upgrading SMB related file.
A similar issue I encountered before:
http://social.technet.microsoft.com/Forums/windowsserver/en-US/b7fcc59b-52d9-4a02-863a-1a529bcb8cb1/temp-doc-etc-files-dont-close-after-a-file-closes-this-causes-locked-files?forum=winserverfiles
It is resolved by upgrading SMB files so maybe it will help on your case.
Another hotfix which may related:
http://support.microsoft.com/kb/983458
If you have any feedback on our support, please send to [email protected]

File locking question

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