[jboss-jira] [JBoss JIRA] (WFCORE-2793) Get rid of the "DeploymentScanner Threads" pool

[Brian Stansberry (JIRA)]

    [ https://issues.jboss.org/browse/WFCORE-2793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13404606#comment-13404606 ] 

Brian Stansberry commented on WFCORE-2793:
------------------------------------------

An important thing to consider is the lifecycle of the pool and what happens to scheduled tasks when the pool is stopped.

The ServerService.ServerScheduledExecutorService uses non-daemon threads. The service stop does a simple shutdown(), with no blocking for completion. The pool has setExecuteExistingDelayedTasksAfterShutdownPolicy(false) set so following the shutdown call any tasks not started will be discarded. But tasks that are in progress will continue. Since the threads are non-daemon they should keep the vm alive until completed.

ServerDeploymentRepository-temp-threads uses daemon threads. The service stop does a simple shutdown(), with no blocking for completion. The pool *does not* have setExecuteExistingDelayedTasksAfterShutdownPolicy(false) set so following the shutdown call any tasks not started will still be executed. But the fact the threads are daemon threads means the VM will exit despite tasks being queued or in progress.

The deployment-scanner uses non-daemon threads. The service stop does a simple shutdown(), with no blocking for completion. The pool *does not* have setExecuteExistingDelayedTasksAfterShutdownPolicy(false) set so following the shutdown call any tasks not started will still be executed. Since the threads are non-daemon they should keep the vm alive until completed.

> Get rid of the "DeploymentScanner Threads" pool
> -----------------------------------------------
>
>                 Key: WFCORE-2793
>                 URL: https://issues.jboss.org/browse/WFCORE-2793
>             Project: WildFly Core
>          Issue Type: Bug
>          Components: Deployment Scanner, Domain Management
>            Reporter: Brian Stansberry
>            Assignee: Brian Stansberry
>
> Look into whether we can consolidate thread usage for scheduled tasks.
> 1) Get rid of the "DeploymentScanner Threads" pool
> The deployment scanner can use the kernel scheduled executor. I'm a bit reluctant in general to allow use of this pool by subsystems as scheduled executors have a fixed size pool, so arbitrary usage by subsystems can result in tying up all the threads doing long running tasks and undesirable behavior. But deployment-scanner is "kernel-ish enough" that I think it's ok.
> This will remove 2 threads.
> The server scheduled executor has 4 threads which is actually pretty high given the very limited usage of it. So I'll consider narrowing it down.
> The big problem with using the server scheduled executor is tying up its threads long running tasks, which the scanner does do. What i'll probably do is just use the scheduled executor to trigger a task which then submits a task on the main ServerService thread pool (which is unlimited in size.) 
> Perhaps I'll abstract this kind of usage pattern into a service, and make that service a generally available kernel capability.
> 2) Get rid of the "ServerDeploymentRepository-temp-threads" pool
> This one is used by DeploymentMountProvider to do file cleanup. Similar discussion applies.



--
This message was sent by Atlassian JIRA
(v7.2.3#72005)