DBMS_PROCESS

131 DBMS_PROCESS

The DBMS_PROCESS package provides an interface to manage the prespawned servers.

This chapter contains the following topics:

131.1 DBMS_PROCESS Overview

By default, Oracle Database can prespawn foreground processes to improve the performance of client connections.

A prespawned process refers to a process that has been spawned but does not have a session yet. When a user connects to the database or a service process is needed, the process performs further initialization as needed.

To manage foreground processes, use the DBMS_PROCESS package. The procedures in this package configure the number of foreground processes for a connection pool, start a connection pool, and stop a connection pool.

131.2 DBMS_PROCESS Security Model

You must be granted the SYSDBA administrative privilege to use the DBMS_PROCESS package.

131.3 Summary of DBMS_PROCESS Subprograms

This table lists the DBMS_PROCESS subprograms and briefly describes them.

Table 131-1 DBMS_PROCESS Package Subprograms

Subprogram	Description
CONFIGURE_POOL Procedure	Configures the minimum number of prespawned processes, the number of prespawned processes in a batch, and the initial number of pre-spawned processes for a foreground connection pool
START_POOL Procedure	Starts a prespawned foreground process pool.
STOP_POOL Procediure	Stops a prespawned foreground process pool.

131.3.1 CONFIGURE_POOL Procedure

This procedure configures the minimum number of prespawned processes, the number of prespawned processes in a batch, and the initial number of pre-spawned processes for a foreground connection pool.

Syntax

DBMS_PROCESS.CONFIGURE_POOL(
   pool_name       IN  VARCHAR2 DEFAULT "SYS_DEFAULT_FOREGROUND_POOL",
   min_count       IN  NUMBER DEFAULT 10,
   batch_count     IN  NUMBER DEFAULT 20,
   init_count      IN  NUMBER DEFAULT 0);

Parameters

Table 131-2 CONFIGURE_POOL Procedure Parameters

Parameter	Description
`pool_name`	Name of the foreground pool
`min_count`	Count after which a batch of prespawned processes will be spawned in the pool (default 10; maximum number of processes 64,000)
`batch_count`	Batch of prespawned servers to be spawned in the pool (default 20). The total value of the `min_count` and `batch_count` values cannot exceed the `PROCESSES` parameter value.
`init_count`	Set of prespawned servers to be spawned in startup, or before a storm of connections, spawned in batches (default 0). Do not exceed the `PROCESSES` parameter value.

Exceptions

Table 131-3 CONFIGURE_POOL Procedure Exceptions

Error	Description
`ORA-456`	Prespawn not enabled
`ORA-457`	Prespawn pool not found
`ORA-458`	Prespawn pool already started
`ORA-459`	Prespawn pool not started
`ORA-460`	Process pool invalid configuration value(s)

Usage Notes

To find information about foreground processes, query the V$PROCESS_POOL dynamic view.

Example

BEGIN
  DBMS_PROCESS.CONFIGURE_POOL (
   pool_name   => 'hrdb_pool',
   min_count   => 40,
   batch_count => 20,
   init_count  => 10);
END;
/

131.3.2 START_POOL Procedure

This procedure starts a prespawned foreground process pool.

Syntax

DBMS_PROCESS.START_POOL(
   pool_name      IN  VARCHAR2 DEFAULT "SYS_DEFAULT_FOREGROUND_POOL");

Parameters

Table 131-4 START_POOL Procedure Parameters

Parameter	Description
`pool_name`	Name of prespawned foreground process pool. To find existing pools, query the `V$PROCESS_POOL` dynamic view.

Exceptions

Table 131-5 START_POOL Procedure Exceptions

Error	Description
`ORA-457`	Prespawn pool not found
`ORA-458`	Prespawn pool already started
`ORA-459`	Prespawn pool not started

Example

BEGIN
  DBMS_PROCESS.START_POOL (
   pool_name   => 'hrdb_pool',
END;

131.3.3 STOP_POOL Procedure

This procedure stops a prespawned foreground process pool.

Syntax

DBMS_PROCESS.STOP_POOL(
   pool_name      IN  VARCHAR2 DEFAULT "SYS_DEFAULT_FOREGROUND_POOL");

Parameters

Table 131-6 STOP_POOL Procedure Parameters

Parameter	Description
`pool_name`	Name of the prespawned foreground process pool. To find existing pools, query the `V$PROCESS_POOL` dynamic view.

Exceptions

Table 131-7 STOP_POOL Procedure Exceptions

Error	Description
`ORA-457`	Prespawn pool not found
`ORA-458`	Prespawn pool already started
`ORA-459`	Prespawn pool not started

Example

BEGIN
  DBMS_PROCESS.STOP_POOL (
   pool_name   => 'hrdb_pool',
END;