[ovirt-devel] Thread pools and ManageExecutorService

[Piotr Kliczewski]

On Mon, Jan 16, 2017 at 10:45 AM, Roy Golan <rgolan at redhat.com> wrote:
> Java EE 7 included ManageExecutorService in its spec. Using Wildfly (as
> certified EE 7 container) we can use it to replace our own ThreadPoolUtil
> implementation and (possibly) Quarz usage.
>
> Managed executor service is a thread pool resource, manage by the container
> and can be controlled via JMX or the startup ovirt-egine.xml.in facility.
> This means that it could be tweaked at runtime as well. The service has
> configured thread factory and queue as well, all described by the xml
>
> In the engine we are using mutli pools, with little to no capabilities of
> tweaking them
> - ThreadPoolUtil - our general threading facade
> - SchedulerThreadPool - the pool we create to pass to quarz

We use 2 pools for quartz with the same implementation

> - HostUpdatesCheckerService.java - internal pool
> - CommandExecutor - coco's pool

There is one more pool use for vdsm event processing:
- ForkJoinPool - created with async mode set

>
> EE gave us a standard way to handle threads, with runtime configuration and
> ability to @inject it into the code, this means once again less code with
> using something the platform already supplies with real tuninig abilities. I
> know #infra has an item quarts, this should be considered as well.

I like the idea to managed pool provided by the container but we should revised
our way of using threads first before we will take any decisions.

>
> Following this thread, if there is no suitable bug already, I'll open one
> for this.
>
> Some code snippets:
>
> @Resource
> private ManagedExecutorService mes;
>
> ...  Future f = mes.submit(() -> doThis())
>
>
> The configuration in ovirt-engine.xml.in (already there today!):
>
> <managed-executor-services>
>   <managed-executor-service
>   name="default"
>   jndi-name="java:jboss/ee/concurrency/executor/default"
>   context-service="default"
>   thread-factory="default"
>   hung-task-threshold="60000"
>   core-threads="5"
>   max-threads="25"
>   keepalive-time="5000"
>   queue-length="1000000"
>   reject-policy="RETRY_ABORT" />
> </managed-executor-services>
>
> Please head here for wildfly docs [1] and here [2] to see a simple example
> (from one of the members of the EG of EE, recommended blog in general)
>
> [1]
> https://docs.jboss.org/author/display/WFLY8/EE+Concurrency+Utilities+Configuration
> [2]
> http://www.adam-bien.com/roller/abien/entry/injecting_an_executorservice_with_java
>
>
>
>
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