Re: SQLFreeHandle hang

J Jayavasanthan wrote:
> Hi,
> My Application hangs on my second call to SQLFreeHandle's 'thread_protect(
> SQL_HANDLE_ENV, environment );' line when I use the Threading option as
> 0/1/2. When I use Threading=3 the default it works fine.
> 
> For the above test I had ConnectionPooling enabled.
> 
> When I disable ConnectionPooling, the SQLFreeHandle with Threading=0/1/2 the
> hang doesn't happen. Is this a bug in configuration or am I missing
> something. My code is tuned to use the same Environment across connections,
> do let me know how I could avoid this,
> 
> Regards,
> Jay
> 

Some people on this list may be surprised/confused where you are now as
you did not close your previous thread by saying that what I previously
suggested to you worked - namely looking at add Threading option to your
ODBC driver configuration. It is generally good practise if you start a
thread and find a resolution to post back explaining how you resolved
the problem so others can see the solution.

Threading = 0 all thread protection in the ODBC driver manager for the
ODBC driver is turned off - unxiODBC will only protect its own internal
structures.

Threading = 1 protects down to the statement level

Threading = 2 protects down to the connection level

Threading = 3 protects down to the environment level

IF you ODBC driver is thread-safe you can set Threading to 0.
On the other hand if you are unsure if your driver is thread-safe but
threads only share the environment you can use Threading = 3. If you are
unsure your driver is thread-safe and threads share connections you need
to use 2 etc.

A hang almost definitely suggests something is protecting some structure
and another thread is attempting to get the same resource and vice versa.

You say you share environments across threads so you should either use 0
(meaning you are saying your ODBC driver is thread-safe and unixODBC
should only protect itself) or 3 meaning unixODBC will stop multiple
threads using the same environment at the same time.

If you set threading to 1 or 2 and multiple threads attempt to use the
same connection or statement you will get problems.

If you are definitely saying setting Threading = 0 and you still get a
problem in thread_protect when using connection pooling I suggest you
report this on one of the unixodbc mailing lists which you can find from
www.unixodbc.org.

Martin
-- 
Martin J. Evans
Easysoft Limited
http://www.easysoft.com

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