WINNT 4.0 + SP6 +ie 5.01
I am using FTP server from IIS 4.0.
I have a C++ application that is adding, updating and deleting files based on a certain time event using FTP commands. In many cases some of my files are locked and I cannot delete or update them. The only way to unlock the files is by stop and re-starting FTP service which is not possible since FTP server is a remote server running on real time for many other real time applications including mine!
Is there any reason for why FTP locks some files?
How can I unlock these files from my code (any language but C++ is prefered)
Thanks a lot.
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I guess, you should check MaxPoolThreads. If they are not sufficient enough to support trafic,your files may get blocked, and you may not be able to rename them. What happens when you restart service is that you close all other connections and then get your job done before many of them are reestablished. If you don't know how to check MaxPoolThreads, I can give detailed explanation.
Hi,
Your FTP server and Windows will not allow you to overwrite a file that is being downloaded, nor will it allow someone to download a file that you are in the process of uploading. This is a familiar problem for database coders... The old locked-record syndrome ;-)
You need to implement a file-lock check in your application. You'll need to actually check the server response to your STOR command.
These URLs cover the FTP protocol:
http://info.internet.isi.e
http://www.cs.rpi.edu/cour
Cheers.
Thanks for all of you.
Rename doesn ot work when the file is locked.
The locked files is not actually used by any other threads or applications. For some strange reason, when I try to delete some files (all are identicals) some of them can be deleted and some other are just get locked.
I tested on a single server from which only one client is trying to download/delete/overwrite the files. Still some of the files get locked. There is no overload on FTP server and there are no other application accessing the files.
I do not know about MaxPoolThreads but it might do the trick. I would appreciate if someone tells me about how to unlock the files using MaxPoolThreads.
Also does this lock expire after sometime or the files will be locked till I stop and restart the service?
Thanks
In fact, MaxPoolThread should be increased only if there is some traffic. If only one user uses it, there is no way to correct problem with MaxPoolThread. Anyway, give it a try:
HKEY_LOCAL_MACHINE\SYSTEM\
then goto Edit, then Add Value, then:
Value Name: MaxPoolThreads
Data Type: REG_DWORD
String: <Range is 0 to 0xFFFFFFFF>
Then close all and Restart.
I highly doubt it will help (knowing the info you gave), so don't try this unless you have no problem with restarting. G-Luck
And I have one more idea. Did you try to use some other application for deleteing/updating the files that are locked. May be you C++ prog is not good enough and fails, but other utility will do the job. Try some common ftp prog (personally I prefer AIT2 (Advanced Internet Tool 2) it is freeware allows to work with downloads and have ftp support for upload/download and all common functions, and can be found at www.tucows.com). Or try to get access from DOS prompt. G-Luck
I doubt it is the C++ program that is causing the problem, because I have seen the same thing with NT4 IIS with people uploading with commercial FTP programs. It does not happen very often, but at least once every few months one of the webmasters from the 30 or so sites we handle for APCUG will email me saying they cant delete or replace a particular file, and I have gone online (using PC Anywhere) and actually tried to delete or rename the file myself, and could not do so, but a reboot of the server always fixes it (i.e. the webmaster can replace the file just with FTP)
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by: campellPosted on 2000-07-21 at 01:03:47ID: 3496594
Ok, this might sound stupid but my experience is that if you rename the file before updating/removing it the ftp server releases it.
Example
a) the file foo.bar is locked by the ftp-server
b) rename the file to _foo.bar
c) now you can delete _foo.bar and make a new foo.bar file
Try it, it might be worth it.