Hello Noel,
Unfortunately I could not reproduce this error on a test bench. It occured
only once on a production machine under some specific circumstances.
Analysing thread dump I could identify operations that both threads were
doing when they entered into deadlock:
"Thread-99":
------------
We're inserting 50k+ rows into a table. ConnectionPool is a standard
org.h2.jdbcx.JdbcConnectionPool.
try(Connection connection = connectionPool.getConnection()) {
connection.setAutoCommit(false);
try(PreparedStatement st = conn.prepareStatement(
"INSERT INTO mytable (fields...) VALUES (?,?,...)") {
for (String[] row : data) {
for (int i = 0; i < row.length; i++) {
st.setString(i + 1, row[i]);
}
st.addBatch();
}
st.executeBatch();
}
// WE'VE ENTERED INTO THE DEADLOCK HERE
*connection.commit();*
} catch (SQLException ex ) {
try {connection.rollback(); } catch (SQLException ex) { /*ignore*/ }
throw ex;
}
"pool-thread-1":
----------------
We're reading a large resultset (60k+ records) from another table.
try(Connection connection = connectionPool.getConnection()) {
connection.setAutoCommit(false);
try(PreparedStatement st = conn.prepareStatement(
"SELECT * FROM another_table WHERE conditions") {
try(ResultSet rs = st.executeQuery()) {
// WE'VE ENTERED INTO THE DEADLOCK HERE ON rs.next(), probably when
reading the last row
white (*rs.next()*) {
// ... map row...
}
}
}
connection.commit();
} catch (SQLException ex ) {
try {connection.rollback(); } catch (SQLException ex) { /*ignore*/ }
throw ex;
}
P.S. As I understand with MULTI_THREADED=1 the deadlock probably will gone?
Salu2,
Antón
El miércoles, 13 de diciembre de 2017, 7:59:08 (UTC+1), Noel Grandin
escribió:
>
> Do you possibly have a test case for this? I can fix it (I think), but I'd
> really like to add a test case.
>
> Note to self: the bug is probably in Command.executeUpdate where for
> multithreaded=false, it needs to lock the session and then the database
> object
>
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