[Sugar-devel] "Another osbuild instance is running" error

[James Cameron]

On Fri, Jan 01, 2016 at 08:38:34PM +0530, Shraddha Barke wrote:
> 
> 
> On Fri, 1 Jan 2016, James Cameron wrote:
> 
> >On Thu, Dec 31, 2015 at 11:26:26PM +0530, Shraddha Barke wrote:
> >>
> >>
> >>On Thu, 31 Dec 2015, James Cameron wrote:
> >>
> >>>On Thu, Dec 31, 2015 at 03:38:02AM +0530, Shraddha Barke wrote:
> >>>>>On Wed, Dec 30, 2015 at 04:30:17AM +0530, Shraddha Barke wrote:
> >>>>>>I am trying to build sugar on Ubuntu 15.04 laptop. After git clone
> >>>>>>and cd into sugar-build I get this error-Another osbuild instance is
> >>>>>>running on executing ./osbuild pull
> >>>>>>I searched the internet and found 2 such threads but the issue wasn't
> >>>>>>resolved.
> >>>>>
> >>>>>There's more than two such threads on sugar-devel at .
> >>>>>
> >>>>>>Is this a bug that needs fixing?
> >>>>>
> >>>>>Yes, it's a bug in osbuild, please fix it.
> >>>>
> >>Hello James,
> >>I made the following changes in check_lock()
> >>
> >>def check_lock():
> >>-    try:
> >>-        fcntl.lockf(get_lock_file(), fcntl.LOCK_EX | fcntl.LOCK_NB)
> >>-    except IOError:
> >>-        return False
> >>-
> >>-    return True
> >>-
> >>
> >>+       pid = os.getpid()
> >>+       try:
> >>+            fcntl.lockf(pid, fcntl.LOCK_EX | fcntl.LOCK_NB)
> >>+       except IOError:
> >>+           return False
> >>+       try:
> >>+           os.kill(pid(), 0)
> >>+       except OSError:
> >>+            return False
> >>+        return True
> >
> >Ah, that's not what I meant.
> >
> >But I was wrong to suggest a redesign using getpid and kill, because
> >my analysis of the code _today_ shows the underlying cause must be
> >something other than locking.
> >
> >Let me explain.
> >
> >check_lock does try fcntl.lock, and if an exception IOError occurs,
> >does return False.
> >
> >But inside the same try clause is a call to get_lock_file.  Therefore
> >any IOError inside get_lock_file will also cause check_lock to return
> >False.
> >
> >A possible error is that the file could not be opened for write,
> >e.g. because it is owned by someone else, or the protection mask
> >(chmod) is wrong, or the directory does not exist, or the directory is
> >protected.
> >
> >def check_lock():
> >   lock_file = get_lock_file()
> >   try:
> >       fcntl.lockf(lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
> >   except IOError:
> >       return False
> >
> >   return True
> >
> >As a result of this change, any problem opening and writing to the
> >file will be reported before the "another instance" error.
> >
> 
> Ah Got it! Thanks :)
> 
> Like you said it's a permission error. I've posted it below -
> 
> Traceback (most recent call last):
>   File "./osbuild", line 504, in <module>
>     if not main():
>   File "./osbuild", line 467, in main
>     if not check_lock():
>   File "./osbuild", line 406, in check_lock
>     lock_file = get_lock_file()
>   File "./osbuild", line 90, in get_lock_file
>     lock_file = open(get_lock_file_path(), "w")
> IOError: [Errno 13] Permission denied:
> '/home/shraddha/git/sugar-build/.lock-host'

Okay, that will certainly stop osbuild from working.

> 
> >>
> >>so that when there is no process running false is returned. However it is
> >>not fixing the bug.
> >>And yeah when I try to delete the lock file, I get 'file or
> >>directory doesn't exist'
> >
> >That's not possible to explain given the data you sent.
> >
> >You said the print statement showed the file path as
> >
> >.../git/sugar-build/.lock-host
> >
> >Presumably ... is something like /home/username
> >
> >Does the .lock-host file still exist?
> >
> >Show me "stat .lock-host"?
> >
> >If the file exists, but you cannot delete it, then osbuild will fail
> >to open it for write.
> >
> 
> stat: cannot stat ‘.lock-host’: No such file or directory
> 
> This is what I get. It's confusing that although it's failing to write,
> stat says no such directory exists!

Ye, that is strange.  On the one hand the file exists and cannot be
opened for write, yet now the file does not exist.

Please check you are in the right directory when you use stat, or use
stat with the same full path to the file (as reported by osbuild);

	stat /home/shraddha/git/sugar-build/.lock-host

I'm trying not to presume any knowledge; if you only type "stat
.lock-host", then the stat program will look for the file .lock-host
in the current directory.  You can see what the current directory is
by typing "pwd".  You can change the current directory using the "cd"
command.

> Kind Regards,
> Shraddha
> 
> >>Sorry for the novice questions :(
> >
> >When you see me say something that doesn't match what you see, please
> >be sure to tell me about it!
> >
> >>
> >>Kind Regards,
> >>Shraddha
> >>
> >>>
> >>>--
> >>>James Cameron
> >>>http://quozl.netrek.org/
> >>>
> >
> >-- 
> >James Cameron
> >http://quozl.netrek.org/
> >


-- 
James Cameron
http://quozl.netrek.org/