Question

I’m trying to achieve better performance for insert on H2 from multiple threads.

I’ve tried four different setups, each with 20 concurrent threads doing inserts:

1. Shared connection;
2. Shared connection disabling autocommit;
3. Connection pool;
4. Connection pool disabling autocommit.

Got the best result with option 4:

Table created with:

create table foo (id int not null auto_increment primary key, name varchar(50))

Code for insert (c is a connection from org.h2.jdbcx.JdbcConnectionPool):

private static void insertDataWithConnection(Connection c, String n) throws SQLException {
    c.setAutoCommit(false);
    PreparedStatement ps = c.prepareStatement("insert into foo (name) values (?)");
    ps.setString(1, n);
    ps.executeUpdate();
    ResultSet rs = ps.getGeneratedKeys();
    rs.next();
    rs.getInt(1);
    rs.close();
    c.commit();
    c.setAutoCommit(true);
    ps.close();
}

The connection string:

jdbc:h2:test;AUTOCOMMIT=OFF;WRITE_DELAY=300;MVCC=TRUE;LOCK_MODE=0;FILE_LOCK=SOCKET

Is it possible to reduce the Thread contention somehow?

P.S.:

• Getting the generated key is important.
• Switching H2 to another embedded database may be an option; but, please, the answers should focus on H2.

Answer 1

We’ve used Multi-version Concurrency control and Multi-threaded options. They do seem to help with some of the contention issues, but they were not a silver bullet.