[unixODBC-support] locking issue

Nick Gorham nick.gorham at easysoft.com
Fri Dec 21 10:45:32 GMT 2007

Chauhan Bhavik-A20762 wrote:

>odbcinst.ini doesn't have "Threading=0" , what is the default behaviour?
>While the process was bloking, I tried with isql with the same
>datasource and it does able to connect and execute some select queries.
 * use just one mutex for all the lists, this avoids any issues
 * with deadlocks, the performance issue should be minimal, if it
 * turns out to be a problem, we can readdress this
 * We also have a mutex to protect the connection pooling code
 * If compiled with thread support the DM allows four different
 * thread strategies
 * Level 0 - Only the DM internal structures are protected
 * the driver is assumed to take care of it's self
 * Level 1 - The driver is protected down to the statement level
 * each statement will be protected, and the same for the connect
 * level for connect functions, note that descriptors are considered
 * equal to statements when it comes to thread protection.
 * Level 2 - The driver is protected at the connection level. only
 * one thread can be in a particular driver at one time
 * Level 3 - The driver is protected at the env level, only one thing
 * at a time.
 * By default the driver open connections with a lock level of 3,
 * this can be changed by adding the line
 * Threading = N
 * to the driver entry in odbcinst.ini, where N is the locking level
 * (0-3)

Nick Gorham
Easysoft Limited
http://www.easysoft.com, http://www.unixODBC.org

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