Getting [SQLITE_BUSY] database file is locked with select statements

Question

If I run multiple threads against my web app I get:

java.sql.SQLException: [SQLITE_BUSY]  The database file is locked (database is locked)
    at org.sqlite.DB.newSQLException(DB.java:383)
    at org.sqlite.DB.newSQLException(DB.java:387)
    at org.sqlite.DB.execute(DB.java:339)
    at org.sqlite.PrepStmt.executeQuery(PrepStmt.java:75)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:96)

I do know that only one thread can write to a sqlite database but I'm only reading from the database. So why do I get this error message ?

BTW: My connection pool looks like this:

<bean class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close" id="dataSource">
    <property name="driverClassName" value="${database.driverClassName}" />
    <property name="url" value="${database.url}" />
    <property name="username" value="${database.username}" />
    <property name="password" value="${database.password}" />
    <property name="initialSize" value="1" />
    <property name="maxActive" value="2" />
    <property name="maxIdle" value="1" />
    <property name="poolPreparedStatements" value="true" />
</bean>

The setup is: Java 1.6, Tomcat 7.0.34, Spring 3.2, Hibernate 3.6.9 and sqlite3 3.7.2

Regards Roger

Answer 1

After some googling I found that it is a bad practice to use multiple connections when connecting to SQLite. See

http://touchlabblog.tumblr.com/post/24474398246/android-sqlite-locking

Set your poolsize maxactive to 1 and try out.

Answer 2

There should be only ONE connection with your application. you can use this to ensure.

public class SqliteHelper {
private static Connection c = null;
public static Connection getConn() throws Exception {
    if(c == null){
    Class.forName("org.sqlite.JDBC");
    c = DriverManager.getConnection("jdbc:sqlite:D:/test.db");
    }
    return c;
    }
}

Answer 3

Note also that this may happen if you accidentally forget to close your connection:

Connection connection;
try {
  Statement statement = connection.createStatement();
  ResultSet resultSet = statement.executeQuery(QUERY);
  if (resultSet.next()) { /* do something */ }
catch (SQLException e) { /* handle exception */ }
finally {
  if (connection != null) {
    try {
      connection.close(); // <-- This is important
    } catch (SQLException e) {
      /* handle exception */
    }
  }
}

While the first database connection may work well once the server is started, subsequent queries may not, depending on how the connection pool is configured.

Answer 4

For anyone who's having issues with it in WSL2:

Happened to me when I was using WSL2 & Datagrip, even tho the database wasn't busy.

It turns out that Datagrip has tried to connect to the database file that existed inside WSL2 via Windows' sqlite3.

Moving the file from WSL2 to a Windows file directory seems to solve this issue