How to read data from Oracle Db using JdbcCursorItemReader with Multi threading

问题

I had spring batch application and configured step like this:

ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
taskExecutor.setCorePoolSize(4);
taskExecutor.setMaxPoolSize(10);
taskExecutor.afterPropertiesSet();
return this.stepBuilderFactory.get("step1")
            .<Mymodel, Mymodel>chunk(2500)              
            .reader(reader())
            .writer(writer())
            .taskExecutor(taskExecutor)
            .build();

And reader like this:

@Bean
public JdbcCursorItemReader<Mymodel> reader() {
    JdbcCursorItemReader<Mymodel> reader = new JdbcCursorItemReader<Mymodel>();
    reader.setDataSource(dataSource);
    reader.setSql("select * from User");
    reader.setRowMapper(new BeanPropertyRowMapper<>(Mymodel.class));
    reader.setVerifyCursorPosition(false);
    return reader;
}

When I execute application , getting this error:

org.springframework.jdbc.UncategorizedSQLException: Attempt to process next row failed; uncategorized SQLException for SQL [select * from User]; SQL state [99999]; error code [17289]; Result set after last row; nested exception is java.sql.SQLException: Result set after last row

Can you please help me to solve this.

回答1:

The JdbcCursorItemReader is not thread-safe as it wraps a ResultSet object which is not thread safe.

You can use a JdbcPaginingItemReader which is thread safe and optionally configure the page size to match the chunk size so that each page is processed in the same thread.

More details in the following answer: https://stackoverflow.com/a/28724199/5019386.

Hope this helps.

来源：https://stackoverflow.com/questions/53939299/how-to-read-data-from-oracle-db-using-jdbccursoritemreader-with-multi-threading