Custom Thread Pools

By default, the connection queue sends requests to the default thread pool. However, you can also create your own thread pools in magnus.conf using a thread pool Init function. These custom thread pools are used for executing NSAPI Service Application Functions (SAFs), not entire requests.

If the SAF requires the use of a custom thread pool, the current request processing thread queues the request, waits until the other thread from the custom thread pool completes the SAF, then the request processing thread completes the rest of the request.

For example, the obj.conf file contains the following:

NameTrans fn="assign-name" from="/testmod" name="testmod" pool="my-custom-pool"
...
<Object name="testmod">
ObjectType fn="force-type" type="magnus-internal/testmod"
Service method=(GET|HEAD|POST) type="magnus-internal/testmod"
fn="testmod_service" pool="my-custom-pool2"
</Object>

In this example, the request is processed as follows:

1. The request processing thread, referred to as A1 in this example, picks up the request and executes the steps before the NameTrans directive.

2. If the URI starts with /testmod, the A1 thread queues the request to the my-custom-pool queue. The A1 thread waits.

3. A different thread in my-custom-pool, called the B1 thread in this example, picks up the request queued by A1. B1 completes the request and returns to the wait stage.

4. The A1 thread wakes up and continues processing the request. It executes the ObjectType SAF and moves on to the Service function.

5. Because the Service function must be processed by a thread in my-custom-pool2, the A1 thread queues the request to my-custom-pool2.

6. A different thread in my-custom-pool2, called C1 in this example, picks up the queued request. C1 completes the request and returns to the wait stage.

7. The A1 thread wakes up and continues processing the request.

In this example, three threads, A1, B1, and C1 work to complete the request.

Additional thread pools are a way to run thread-unsafe plug-ins. By defining a pool with a maximum number of threads set to 1, only one request is allowed into the specified service function. In the previous example, if testmod_service is not thread-safe, it must be executed by a single thread. If you create a single thread in the my-custom-pool2, the SAF works in a multi-threaded Web Server.

For more information on defining thread pools, see thread-pool-init in Sun Java System Web Server 7.0 Update 5 Administrator’s Configuration File Reference.