[pybsddb] Random "key not found"?

[David Wolever]

Darn, just as I feared -- I was doing something stupid.

Thanks for the help, much appreciated.

David

On 21-Aug-08, at 2:11 PM, George Feinberg wrote:

> David,
>
> Read/write concurrent applications need to either use transactions or
> the CDS
> environment (multiple readers, single-writer) in order to protect  
> state.
>
> George
>
> On Aug 21, 2008, at 11:57 AM, David Wolever wrote:
>
>> Hey,
>> I've been doing some load testing on my application, and I've
>> noticed that, from time to time, "DB.get(...)" will return "key not
>> found", even though the key is there and previous/subsequent gets()
>> succeed.
>>
>> I've been able to reproduce the problem with a simple script (or,
>> at least, as simple as a threaded script can be), which I've  
>> attached.
>>
>> This is what should happen after a couple tries:
>> ...
>> --------------------------------------------------------------------- 
>> -
>> Exception in thread 25578496:
>> Traceback (most recent call last):
>>   File "bsddb_problem.py", line 57, in child
>>     raise Exception("Error getting key %s: %s" %(id, e))
>> Exception: Error getting key 60: (-30988, 'DB_NOTFOUND: No matching
>> key/data pair found')
>> --------------------------------------------------------------------- 
>> -
>> ...
>>
>> By turning on debugging you can see that previous gets on the key
>> (in this case, '60') have succeeded, and if something like "db.get
>> (id)" is added in the exception handler, the correct value is
>> retrieved.
>>
>> So, my questions:
>> - Am I doing anything really stupid?
>> - Is there any way to get around it? I've tried using cursors, and
>> that _seems_ to work, but I don't entirely understand why, so I'm a
>> little wary.
>>
>> Thanks,
>> David
>>
>>
>> <bsddb_problem.py>_______________________________________________
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>
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