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behalf of the client. Please see the Oracle Rdb documentation for information on the default

transaction mechanism provided by SQL.

8.5 Executor Sub-process used with the Rdb Native driver

To improve multi-threaded concurrent access to the database while using the Rdb Native

driver, you may specify that separate sub-process executors should be started for each

connection request.

By default all database operations within a standard Rdb Native driver instance are carried

out synchronously, within a single OpenVMS process. This synchronization is required as

Rdb will only let one thread carry out a database operation at a time. This may limit the

general concurrency that may be seen if you are using the Rdb Native driver within a multi-

threaded environment.

To improve concurrency in a multi-threaded environment you can request the Rdb Native

driver to start-up a separate executor for the database connection.

To start a separate executor for the connection you need to specify the multiprocess switch

on connection URL you use for your database connection.

Connection conn = DriverManager.getConnection(

"jdbc:rdbNative:my_db_dir:pers@multiprocess=true",

user, pass);

Note that this switch is only available when you use the Rdb Native driver.

As a separate sub-process is created for each connection made, output written by the executor

process to SYS$OUTPUT and SYS$ERROR will be redirected to log files specific to that

sub-process. You should ensure that your process has write access to the log directory

RDB$JDBC_LOGS.

8.5.1 Setting Maximum Handshake Tries and Wait Duration

When the main process starts an executor process a handshake protocol is established

between the two processes to allow them to carry out subsequent inter-process

communication.

The main process will attempt 100 times in quick succession to establish the handshake, and

then, by default, will try 500 more times with a delay of 10 ms between each try.

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EXP Computer ThinConnect4 Guía de usuario Pagina 112