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

[Shraddha Barke]

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'

>>
>> 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!

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/
>