Hmmm...bad assumption on my part....seems so logical that if it's busy just try
again -- and that idea worked on Liubin's problem. I see this
http://www.sqlite.org/c3ref/stmt.html -- but it doesn't quite address the BUSY
condition.
I also found this thread
http://www.mail-archive.com/sqlite-users@sqlite.org/msg06916.html
Which doesn't mention using reset (perhaps he is but just doesn't mention it)
but using busy_handler instead. This guy seems to have stressed it pretty hard.
Michael D. Black
Senior Scientist
Northrop Grumman Mission Systems
________________________________
From: sqlite-users-boun...@sqlite.org on behalf of Pavel Ivanov
Sent: Thu 5/13/2010 6:40 AM
To: General Discussion of SQLite Database
Subject: Re: [sqlite] multi processes,so many errores of SQLITE_BUSY and
SQLITE_MISUSE
> I assume you want the sqllite3_stmt to work -- so you need to loop that while
> it's busy.
Michael, don't give bad advices.
The most general advice when one gets SQLITE_BUSY is to reset/finalize
all statements and rollback current transaction. It's only in certain
type of transactions and certain type of statements one can loop while
sqlite3_stmt returns SQLITE_BUSY. But even in this case one must call
sqlite3_reset on the statement that returned SQLITE_BUSY. And this
call to sqlite3_reset will return SQLITE_BUSY again.
Pavel
On Thu, May 13, 2010 at 7:20 AM, Black, Michael (IS)
<michael.bla...@ngc.com> wrote:
> It also means you're not handling the SQLITE_BUSY from the sqlite3_stmt()
> before it.
> I assume you want the sqllite3_stmt to work -- so you need to loop that while
> it's busy.
>
> Michael D. Black
> Senior Scientist
> Northrop Grumman Mission Systems
>
>
> ________________________________
>
> From: sqlite-users-boun...@sqlite.org on behalf of liubin liu
> Sent: Thu 5/13/2010 2:07 AM
> To: sqlite-users@sqlite.org
> Subject: Re: [sqlite] multi processes, so many errores of SQLITE_BUSY and
> SQLITE_MISUSE
>
>
>
>
> I see many SQLITE_BUSY returned from sqlite3_finalize(). Are they memory leak
> because it don't succeed in finalizing the sqlite3_stmt pointer?
>
>
>
>
> Black, Michael (IS) wrote:
>>
>> SQLITE_BUSY is not an error...just a fact.
>>
>> All your processes cannot work on the database at the same time...at least
>> not when one of them is doing an insert. You could be changing the table
>> while you're scanning it. EXXCLUSIVE doesn't change that idea.
>>
>> Somebody please correct me if I'm wrong on this one...
>> I think sqlite can work with multiple processes just doing read-onliy
>> operations (like SELECT). It's just the write operations
>> (INSERT/UPDATE) which will cause SQLITE_BUSY to occur.
>>
>> Michael D. Black
>> Senior Scientist
>> Northrop Grumman Mission Systems
>>
>>
>> ________________________________
>>
>> From: sqlite-users-boun...@sqlite.org on behalf of liubin liu
>> Sent: Tue 5/11/2010 9:20 PM
>> To: sqlite-users@sqlite.org
>> Subject: Re: [sqlite] multi processes, so many errores of SQLITE_BUSY and
>> SQLITE_MISUSE
>>
>>
>>
>>
>> Thank you very much!
>>
>> It may be because my system's resource is limited. It's a embedded system
>> containing 32M RAM, ARM9 CPU.
>>
>> My "reiterating 20 times" is already using usleep().
>>
>> After I add the loop in the prepare statements, the system performance is
>> still very bad... And there are still many errores of SQLITE_BUSY.
>>
>> The only improvement is the disappear of the error of SQLITE_MISUSE.
>>
>> And I tried to use the "BEGIN EXCLUSIVE TRANSACTION". The things are same
>> with them without using it.
>>
>>
>>
>>
>>
>>
>>
>> Black, Michael (IS) wrote:
>>>
>>> Your "reiterating 20 times" is not using a usleep so you'll blow by this
>>> most every time it's busy.
>>>
>>> Do this instead in all your proc's
>>>
>>> ret = sqlite3_step (p_stmt);
>>> if (SQLITE_BUSY == ret)
>>> {
>>> int n=0;
>>> usleep(100000); // try one more time before error
>>> while ((ret=sqlite3_step(p_stmt))==SQLITE_BUSY) {
>>> printf("proc1 ret==BUSY %d\n",++n);
>>> usleep(100000);
>>> }
>>> }
>>>
>>> And you'll also need to handle "database is locked" coming from your
>>> prepare statements. I saw that error too.
>>> You'll need to loop there too.
>>>
>>> The more you drop the usleep time the more times it will show as busy.
>>> 1/10th or 1/100th of second is about all you want I would think.
>>>
>>> And get rid of the usleep at the bottom of each proc -- it's pretty
>>> useless at 100 microseconds. You don't need to sleep unless you're busy.
>>>
>>> I tested your code with this and got no errors at all -- just a bunch of
>>> BUSY messages.
>>>
>>>
>>> Not sure what your purpose is in sqlrun.c with looping and killing.
>>> Looks
>>> pretty squirrely to me. You're not waiting for the forks to finish so
>>> what is your logic here?
>>>
>>> Michael D. Black
>>> Senior Scientist
>>> Northrop Grumman Mission Systems
>>>
>>>
>>> ________________________________
>>>
>>> From: sqlite-users-boun...@sqlite.org on behalf of liubin liu
>>> Sent: Tue 5/11/2010 4:57 AM
>>> To: sqlite-users@sqlite.org
>>> Subject: [sqlite] multi processes, so many errores of SQLITE_BUSY and
>>> SQLITE_MISUSE
>>>
>>> ...
>>>
>>> --
>>> View this message in context:
>>> http://old.nabble.com/multi-processes%2C-so-many-errores-of-SQLITE_BUSY-and-SQLITE_MISUSE-tp28522127p28522127.html
>>> Sent from the SQLite mailing list archive at Nabble.com.
>>>
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>>
>> --
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