I check in the sqlite3.c code for the SQLITE_THREADSAFE. I can't found
any difference between SQLITE_THREADSAFE=1 and SQLITE_THREADSAFE=2. I
found only differences if SQLITE_THREADSAFE=0 or SQLITE_THREADSAFE>0
Have I miss something?
Il 06/10/2010 8.07, Michele Pradella ha scritto:
> So let me know if I understand:
>
> 1. SQLITE_THREADSAFE=0: lock are disabled at all, and you can use
> this if the application is not multi thread, so if there's only
> one thread that can use the SQLITE library
> 2. SQLITE_THREADSAFE=1: is the highest level of thread safety, so if
> the slowest mode but you do not have to care about multiple access
> to the SQLITE library from different thread. You need this in a
> multi thread application to be sure to avoid damage to the DB
> 3. SQLITE_THREADSAFE=2: it's a compromise between thread safety and
> speed. The library are thread safe but you have to avoid that two
> thread can use at the same time the same DB connection. So if you
> have for example 3 thread and every thread access the library with
> it own connection there's no problem So you can use two different
> DB connection from two thread at the same time without problem. Is
> that right?
>
>
> Il 05/10/2010 18.34, Jay A. Kreibich ha scritto:
>> On Tue, Oct 05, 2010 at 12:44:59PM +0200, Zaher Dirkey scratched on the wall:
>>> On Tue, Oct 5, 2010 at 4:55 AM, Jay A. Kreibich<j...@kreibi.ch> wrote:
>>>
>>>> On Mon, Oct 04, 2010 at 07:25:05PM -0700, Dustin Sallings scratched on the
>>>> wall:
>>>>
>>>>
>>>> The main difference between =1 and =2 is that =2 assumes you more or
>>>> less know what you're doing and will either lock a database handle as
>>>> you pass it between threads or you'll keep it private to a thread.
>>>>
>>>> =1 is designed to be more or less idiot proof, and will simply not
>>>> let you do something stupid with a database handle, like have two
>>>> threads try to execute two different statements at the same time.
>>>>
>>> What if two therad make insert or update then commit, what is happen to the
>>> second thread after the first made commit?.
>> The second thread will block if it attempts to use a database
>> connection that the first thread is already using. Once the first
>> thread finishes (either with an explicit COMMIT/ROLLBACK, or because
>> all auto-commit transactions go out of scope) then the first thread
>> will release the database connection and the second thread will wake
>> up and allowed to proceed. That's why the =1 mode is called "serial"...
>> it automatically serializes the database statements.
>>
>> At least, I'm pretty sure that's how it works. I generally avoid
>> threaded code, and when I do use it, I tend to use thread-specific
>> resources that are carefully locked and guarded.
>>
>> -j
>>
>
--
Selea s.r.l.
Michele Pradella R&D
SELEA s.r.l.
Via Aldo Moro 69
Italy - 46019 Cicognara (MN)
Tel +39 0375 889091
Fax +39 0375 889080
*michele.prade...@selea.com* <mailto:michele.prade...@selea.com>
*http://www.selea.com*
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