Hi All,
I have an application which starts two or more threads.
Each thread open a separate connection to the database and in each
transaction, modifies various tables of it.
I use third-party library to access the SQLite database which make it
possible to have an uniform access to different DBMS. I do not control
directly the calls to sqlite3 funcution, but I have the source code of
the library so I can see the sequence of calls.
The sqlite3 version I am using is 3.7.9 .
The sequence of actions of a thread is the following:
//--- Start Thread ---
....
// Open connection to DB
sqlite3 *handle(NULL);
sqlite3_open_v2("C:...\dbase", &handle,
SQLITE_OPEN_SHAREDCACHE|SQLITE_OPEN_FULLMUTEX|SQLITE_OPEN_READWRITE );
sqlite3_busy_timeout(handle, 30000);
sqlite3_step("PRAGMA foregn_keys = ON");
sqlite3_reset(..)
sqlite3_clear_bindings(..);
// Begin a new transaction
BEGIN TRANSACTION EXCLUSIVE
...
SELECT ....
INSERT ...
UPDATE ...
COMMIT
...
// Begin a new transaction
BEGIN TRANSACTION EXCLUSIVE
...
SELECT ....
INSERT ...
UPDATE ...
...
COMMIT
sqlite3_close();
//--- END Thread ---
When I have four or more threads accessing to the database I see the
error message: "database table is locked".
This happens when a thread begins a new Transaction, probably because
another thread already has an excluse access to the database.
I supposed that, setting the "busy timeout" to an high value (30 secs in
my case) should manage this kind of problems, but probably I am wrong or
I am not using sqlite functions in the right way.
Can any one suggest me any strategies for overcome this problem ?
Tank you for your help.
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