Hi all,
I'm doing a little stress test on a server application and run into
a problem when two threads are trying to access the database.
Here is the background:
1. shared cache is enabled prior open any DB connection.
2. Each thread then opens a DB connection.
3. Thread A just reads table entries continuosly by
doing sqlite3_prepare_v2 and followed by some sqlite3_step to parse the
result set.
He then uses sqlite3_finalize and after a few ms he repeats everything.
4. Thread B is triggered to update or insert some a new values
in some tables.
To do so I obtain an EXCLUSIVE transaction, do the insert/update and COMIT.
Now, a problem arises occasionally that thread A gets an SQLITE_MISUSE when
trying to call sqlite3_step, most likely because thread B currently writes into
the DB, I guess.
Now, my question:
How to handle the SQLITE_MISUSE ?
I'm prepared to deal with SQLITE_BUSY or SQLITE_LOCKED but I don't know what
to do when a sqlite3_step returns the SQLITE_MISUSE error.
Without the shared_cache enabled I don't get SQLITE_MISUSE but the usual
busy or locked states and I can just wait until the locking dissapeared.
Is it recommended to use additionally the "PRAGMA read_uncommitted = True;" ?
Maybe I should use an exclusive transaction on the simple "SELECT * FROM table"
calls but that will block any parallel reads, not very useful.
Actually, I don't understand why I don't get a LOCK state in shared
cache mode as well, although I think it is by design.
thank you
Marcus Grimm
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