A work manager acts as a thread pool for application components
that use asynchronous beans. Use the administrative console to configure
work managers.
Before you begin
If you are not familiar with work managers, review the conceptual
topic,
Work managers.
About this task
The work manager service is always enabled. In previous versions
of the product, the work manager service could be disabled using the
administration console or configuration service. The work manager
service configuration objects are still present in the configuration
service, but the enabled attribute is ignored.
You can define multiple
work managers for each cell. Each work manager is bound to a unique
place in Java Naming and Directory Interface (JNDI).
Note: The
work manager service is only supported from within the Enterprise
Java Beans (EJB) Container or Web Container. Looking up and using
a configured work manager from a J2EE application client container
is not supported.
Procedure
- Start the administrative console.
- Select Resources > Asynchronous beans > Work managers.
- Specify a Scope value and click New.
- Specify the required properties for work manager settings.
- Scope
- The scope of the configured resource. This value indicates the
location for the configuration file.
- Name
- The display name for the work manager.
- JNDI Name
- The Java Naming and Directory Interface (JNDI) name for the work
manager. This name is used by asynchronous beans that need to look
up the work manager. Each work manager must have a unique JNDI name
within the cell.
- Number of Alarm Threads
- The maximum number of threads to use for processing alarms. A
single thread is used to monitor pending alarms and dispatch them.
An additional pool of threads is used for dispatching the threads.
All alarm managers on the asynchronous beans associated with this
work manager share this set of threads. A single alarm thread pool
exists for each work manager, and all of the asynchronous beans associated
with the work manager share this pool of threads.
- Minimum Number Of Threads
- The number of threads to be kept in the thread pool, created as
needed.
- Maximum Number Of Threads
- The maximum number of threads to be created in the thread pool.
The maximum number of threads can be exceeded temporarily if the Growable check
box is selected. These additional threads are discarded when the work
on the thread completes.
- Thread Priority
- The priority to assign to all threads in the thread pool.
Every
thread has a priority. Threads with higher priority are run before
threads with lower priority. For more information about how thread
priorities are used, see the javadoc for the setPriority method of
the java.lang.Thread class in the Java Standard Edition specification.
- [Optional] Specify a Description and a Category for
the work manager.
- [Optional] Select the Service Names (J2EE contexts)
on which you want this work manager to be made available. Any asynchronous
beans that use this work manager then inherit the selected J2EE contexts
from the component that creates the bean. The list of selected services
also is known as the "sticky" context policy for the work manager.
Selecting more services than are actually required might impede
performance.
Other optional fields include:
- Work timeout
- Specifies the number of milliseconds to wait before a scheduled
work object is released. If a value is not specified, then the timeout
is disabled.
- Work request queue size
- Specifies the size of the work request queue. The
work request queue is a buffer that holds scheduled work objects and
can be a value of 1 or greater. The thread pool pulls work from this
queue. If you do not specify a value or the value is 0, the queue
size is managed automatically. When the queue size is managed automatically,
it is computed as the (minimum_number_of_threads + maximum_number_of_threads)
/ 2. If this value computes to a zero value, a queue size of 1 is
used. Large values can consume significant system resources.
- Work request queue full action
- Specifies the action taken when the thread pool is exhausted,
and the work request queue is full. This action starts when you submit
non-daemon work to the work manager. If set to FAIL, the work manager
API methods creates an exception instead of blocking.
- Default transaction class
- Specifies the transaction class name used to classify work run
by this work manager instance when the z/OS Work Load Manager Service
class information is not contained in the work context information.
- Daemon transaction class
- Specifies the transaction class name used to classify "daemon"
work initiated by this work manager instance.
- Save your configuration.
Results
The work manager is now configured and ready for access by
application components that need to manage the start of asynchronous
code.