I successfully use libdbi in production with MySQL and Postgres servers in
multithreading, but by multithreading I mean that I am using one connection
per thread, and a variable pool of threads, with connections to MySQL and
Postgres on the same libdbi instance. A server going down does not cause any
issue.
However, you might be encountering an issue with the dbi_conn_error, which
last time I checked was not thread safe, because it is sharing a static char
* between all connections! I guess I should have filed a bug.
Here's how I get around it:
// dbi_conn_error is not thread safe, it uses a static char *
// internally which could be freed twice if the function is not
locked
boost::mutex::scoped_lock lock(sErrorMutex);
const char *dbError = NULL;
int errNum = dbi_conn_error(mDbConn, &dbError);
Logger::logX( LOG_WARNING, "1504 - Failed to connect to DB with
connection string \"%s\", reason: %d - %s",
dbAccess->getConnection().c_str(), errNum, dbError );
Anyway, why don't you "gdb" your crash, it will give you a better hint of
where the problem actually is.
Regards,
Emmanuel.
On Thu, Aug 19, 2010 at 10:24 AM, Markus Hoenicka <
markus.hoeni...@mhoenicka.de> wrote:
> Shaofeng Yang <breath...@gmail.com> was heard to say:
>
> > Greeting,
> >
> > I am working on a thread pool with libdbi and libdbi-driver-mysql. i saw
> a
> > problem that program crashes if mysql server goes away for one thread. i
> am
> > using the thread safe version of libdbi and the design of my thread pool
> > doesn't have problems. The problem comes out from libdbi mysql driver,
> > which is compiled against libmysqlclient not libmysqlclient_r by
> default. I
> > am just wondering what i should do to make libdbi mysql driver
> thread-safe.
> > Can I just change the makefile.am to use -lmysqlclient_r instead
> > of -lmysqlclient? Is dbd_mysql.c thread-safe?
>
> Hi,
>
> I assume you connect to the server before starting your threads. Would
> it be possible to use the new interface (available in CVS and in the
> eventually to be released libdbi version 0.9) which allows to manage
> independent instances of libdbi in a single process? You could use
> that to connect to the server in each thread separately, so if one of
> them goes away it should not affect the other instances.
>
> I'm not familiar with thread-safe programming, so I have no idea if
> libdbi is currently thread-safe. Someone more familiar with this issue
> should speak up.
>
> As for libmysqlclient and libmysqlclient_r: if these libraries use the
> same API, I guess you can simply change Makefile.am to use the latter.
> If that works, we should probably make this a configurable build option.
>
> regards,
> Markus
>
>
>
> --
> Markus Hoenicka
> http://www.mhoenicka.de
> AQ score 38
>
>
>
>
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