Administering Thread Pools

This chapter provides procedures for administering thread pools in the Payara Server environment by using the asadmin command-line utility.

Instructions for accomplishing these tasks by using the Administration Console are contained in the Administration Console online help.

About Thread Pools

The Virtual Machine for the Java platform ((Java Virtual Machine) or JVM machine) can support many threads of execution simultaneously. To help performance, Payara Server maintains one or more thread pools. It is possible to assign specific thread pools to connector modules, to network listeners, or to the Object Request Broker (ORB).

One thread pool can serve multiple connector modules and enterprise beans. Request threads handle user requests for application components. When Payara Server receives a request, it assigns the request to a free thread from the thread pool. The thread executes the client’s requests and returns results. For example, if the request needs to use a system resource that is currently busy, the thread waits until that resource is free before allowing the request to use that resource.

Configuring Thread Pools

You can specify the minimum and maximum number of threads that are reserved for requests from applications. The thread pool is dynamically adjusted between these two values.

Default Thread Pool Size

The thread pool thread-pool-1 starts with a minimum size of 2 instead of 1 (like in previous versions)

This includes the benefit of allowing users to execute tasks concurrently using the ManagedExecutorService and ManagedScheduledExecutorService components included with Java EE Concurrency Utilities (JSR-236). Without this change, new tasks submitted to these service components would just have been queued in a linear fashion.

This minor optimization is configured on the default domain template (so all newly created domains inherit it).

To Create a Thread Pool

Use the create-threadpool subcommand in remote mode to create a thread pool.

The minimum thread pool size that is specified signals the server to allocate at least that many threads in reserve for application requests. That number is increased up to the maximum thread pool size that is specified. Increasing the number of threads available to a process allows the process to respond to more application requests simultaneously.

If one resource adapter or application occupies all the Payara Server threads, thread starvation might occur. You can avoid this by dividing the Payara Server threads into different thread pools.

Ensure that the server is running. Remote subcommands require a running server.
Create a new thread pool by using the create-threadpool subcommand.
Information about options for the subcommand is included in this help page.
To apply your changes, restart Payara Server. See To Restart a Domain.

Restart is not necessary for thread pools used by the web container.

Example 5-1 Creating a Thread Pool

asadmin> create-threadpool --maxthreadpoolsize 100
--minthreadpoolsize 20 --idletimeout 2 threadpool-1
Command create-threadpool executed successfully

This example creates threadpool-l.

To List Thread Pools

Use the list-threadpools subcommand in remote mode to list the existing thread pools.

Ensure that the server is running. Remote subcommands require a running server.
List the existing thread pools by using the list-threadpools subcommand.

Example 5-2 Listing Thread Pools

asadmin> list-threadpools
threadpool-1
Command list-threadpools executed successfully

This example lists the existing thread pools.

To Update a Thread Pool

Use the set subcommand to update the values for a specified thread pool.

List the existing thread pools by using the list-threadpools subcommand.
Modify the values for a thread pool by using the set subcommand.
The thread pool is identified by its dotted name.
To apply your changes, restart Payara Server. See To Restart a Domain.

Restart is not necessary for thread pools used by the web container.

Example 5-3 Updating a Thread Pool

asadmin> set server.thread-pools.thread-pool.http-thread-pool.max-thread-pool-size=8
Command set executed successfully

This example sets the max-thread-pool-size from its previous value to 8.

To Delete a Thread Pool

Use the delete-threadpool subcommand in remote mode to delete an existing thread pool. Deleting a thread pool will fail if that pool is referenced by a network listener.

Ensure that the server is running. Remote subcommands require a running server.
List the existing thread pools by using the list-threadpools subcommand.
Delete the specified thread pool by using the delete-threadpool subcommand.
To apply your changes, restart Payara Server. See To Restart a Domain.

Restart is not necessary for thread pools used by the web container.

Example 5-4 Deleting a Thread Pool

asadmin> delete-threadpool threadpool-1
Command delete-threadpool executed successfully

This example deletes threadpool-1.

EJB Thread Pool

The EJB Thread Pool is for prepared EJB beans which are ready for usage, this means there is no instantiation and initialization overhead when the bean is used. It can also be used to limit the number of concurrent beans in use.

An individual bean can specify a configuration that overrides the configuration of the EJB container in the <bean-pool> element of the glassfish-ejb-jar.xml file.

EJB Thread Pool Configuration Properties

The EJB Thread Pool has the following properties configured by default.

Setting Name	Default Value	Description
Core Pool Size	16	The minimum number of threads in the EJB container thread pool
Max Pool Size	32	The maximum number of threads in the EJB container thread pool
Keep Alive Seconds	60	The time, in seconds, which threads in excess of thread-core-pool-size are deleted
Queue Capacity	Integer.MAX_VALUE (2,147,483,647)	The size, in bytes, of the thread pool queue which stores new requests while new threads are created if more than thread-core-pool-size number of threads are running.
Allow Core Thread Timeout	false	All threads, including core threads, are subject to termination after thread-keep-alive-seconds
Prestart All Core Threads	false	Threads in the EJB container thread pool are started even if no requests have arrived, and the pool has a non-empty queue

Setting Name

Default Value

Description

Core Pool Size

The minimum number of threads in the EJB container thread pool

Max Pool Size

The maximum number of threads in the EJB container thread pool

Keep Alive Seconds

The time, in seconds, which threads in excess of thread-core-pool-size are deleted

Queue Capacity

Integer.MAX_VALUE (2,147,483,647)

The size, in bytes, of the thread pool queue which stores new requests while new threads are created if more than thread-core-pool-size number of threads are running.

Allow Core Thread Timeout

false

All threads, including core threads, are subject to termination after thread-keep-alive-seconds

Prestart All Core Threads

false

Threads in the EJB container thread pool are started even if no requests have arrived, and the pool has a non-empty queue

Configuring the EJB Thread Pool

The EJB thread pool can be configured with either the admin console or the asadmin CLI, by making use of the following configuration properties.

Property Name Value Constraints

Property Name	Value Constraints
thread-core-pool-size	Cannot be less than 0, larger than max int, and must be larger than `thread-max-pool-size`
thread-max-pool-size	Cannot be less than 1 or greater than max int
thread-keep-alive-seconds	Cannot be less than 0 or greater than max int
thread-queue-capacity	Cannot be less than 1 or greater than max int
allow-core-thread-timeout	Must be true or false
prestart-all-core-threads	Must be true or false

thread-core-pool-size

Cannot be less than 0, larger than max int, and must be larger than thread-max-pool-size

thread-max-pool-size

Cannot be less than 1 or greater than max int

thread-keep-alive-seconds

Cannot be less than 0 or greater than max int

thread-queue-capacity

Cannot be less than 1 or greater than max int

allow-core-thread-timeout

Must be true or false

prestart-all-core-threads

Must be true or false

Using the Admin Console

To configure the EJB thread pool using the admin console, go to Configuration → [instance-configuration] → EJB Container and scroll down to see Additional Properties.

Add a new additional property, set the Name to the property name from the table above of the property you want to set, and set the Value to a valid value for that property.

Admin Console Configuration

Using the Asadmin CLI

To configure the EJB thread pool with the asadmin CLI, execute the following set command, replacing the configName with the name of your configuration, the property name with a property name from the table above and a valid value for that property.

asadmin set configs.config.${configName}.ejb-container.property.${propertyName}=${propertyValue}