There's no use checking before (if that is possible), it still can get locked between the check and your next call. Better would be to make your call, and handle possible exceptions, eg. retry a number of times and report an error after too much retries.
SQLiteFullException. An exception that indicates that the SQLite database is full. SQLiteMisuseException. This error can occur if the application creates a SQLiteStatement object and allows multiple threads in the application use it at the same time. SQLiteOutOfMemoryException.
SQLite uses POSIX advisory locks to implement locking on Unix. On Windows it uses the LockFile(), LockFileEx(), and UnlockFile() system calls. SQLite assumes that these system calls all work as advertised. If that is not the case, then database corruption can result.
Somewhere along the way a connection is getting left open. Get rid of OpenConnection
and CloseConnection
and change ExecuteNonQuery
to this:
using (SQLiteConnection c = new SQLiteConnection(ConnectionString))
{
c.Open();
using (SQLiteCommand cmd = new SQLiteCommand(sql, c))
{
cmd.ExecuteNonQuery();
}
}
Further, change the way you read data to this:
using (SQLiteConnection c = new SQLiteConnection(ConnectionString))
{
c.Open();
using (SQLiteCommand cmd = new SQLiteCommand(sql, c))
{
using (SQLiteDataReader rdr = cmd.ExecuteReader())
{
...
}
}
}
Do not attempt, to manage connection pooling on your own like you are here. First, it's much more complex than what you have coded, but second, it's handled already inside the SQLiteConnection
object. Finally, if you're not leveraging using
, you're not disposing these objects properly and you end up with issues like what you're seeing now.
You can use 'using' statement as below, that will make sure connection & command disposed correctly even in exception
private static void ExecuteNonQuery(string queryString)
{
using (var connection = new SQLiteConnection(
ConnectionString))
{
using (var command = new SQLiteCommand(queryString, connection))
{
command.Connection.Open();
command.ExecuteNonQuery();
}
}
}
You should close your DataReader before attempting to write any data to the database. Use:
dr.Close();
after you finish using the DataReader.
In my case it was very stupid of me, I was making changes in SQLite browser and did not click on write changes, which locked the DB to be modified by the services. After I clicked the Write changes button, all the post request worked as expected.
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