No, that's not safe at all.... unless all the access is read-only.
alex
On Thu, Oct 22, 2009 at 7:36 AM, Chas Emerick <[email protected]> wrote:
> Alex,
>
> Thank you for the clarification. Just to make sure we're understanding
> each other, I'm actually asking about multiple readers, each opening and
> using their own RecordManagers. Your mention of synchronization leads me to
> think you're talking about multiple threads reading from a single
> RecordManager.
>
> Just FYI, I'm being careful here because I came across a mention of RM
> changing files on disk when *reading*, which surprised me (can't find the
> link right now)...
>
> Thanks again,
>
> - Chas
>
> On Oct 22, 2009, at 10:27 AM, Alex Boisvert wrote:
>
> Individual concurrent reads are safe. Pretty much everything is
> synchronized at the top of level.
>
> However, iterators / tuple browsers are unsafe under concurrent updates.
> You would have to synchronize on the RecordManager instance to maintain a
> consistent view while iterating.
>
> alex
>
>
> On Thu, Oct 22, 2009 at 5:10 AM, Chas Emerick <[email protected]>wrote:
>
>> I've been plumbing around the list archives for a while, but they're
>> something of a jumble (thanks, Sourceforge!), so I figured I'd open a
>> new thread to ask:
>>
>> What level of read concurrency does jdbm support?
>>
>> What seems clear is that, to be safe, there should only be one thread
>> writing to a jdbm database (although it appears that it is possible
>> for multiple threads to participate in a transaction, I'm perfectly
>> fine with serializing all write access). However, I came across at
>> least a number of comments that lead me to believe that concurrent
>> reads are unsafe as well, although they're all from pre-history (e.g.
>> 2001).
>>
>> Thanks,
>>
>> - Chas
>>
>>
>>
>>
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