Hi,
I see no logic, which actually submits something to the queue. So I am not
sure what is the execution profile.
If you submit the a short task to the queue, the result is easy to explain.
Starting from 1.609.x, Jenkins Queue has a snapshoting engine, which reduce
the load on the queue and prevents interlocks between queue maintenance
logic and WebUI.
So methods 1, 4, and 5 effectively get snapshot reference, which they use
in their logic. Methods 3 and 4 work with the queue directly, so they may
be getting a renewed snapshot, where the queue task has already exited the
queue. Then it may easily have 0.
BR, Oleg
воскресенье, 5 февраля 2017 г., 1:19:24 UTC+1 пользователь Markus Winter
написал:
>
> Hi,
> I encounter a strange behaviour of the Queue object.
> The following code is a simple POC for the problem I have.
>
> import java.io.IOException;
> import java.util.List;
> import java.util.concurrent.ExecutorService;
> import java.util.concurrent.Executors;
> import java.util.logging.Logger;
>
> import org.kohsuke.stapler.StaplerRequest;
> import org.kohsuke.stapler.StaplerResponse;
>
> import hudson.Extension;
> import hudson.model.ManagementLink;
> import hudson.model.Queue;
> import hudson.security.Permission;
> import jenkins.model.Jenkins;
>
> @Extension
> public class ManagedLink extends ManagementLink
> {
>
> private static final Logger logger =
> Logger.getLogger(ManagedLink.class.getName());
> private static ManagedLink instance;
> Queue.Item[] items = null;
> Queue queue;
> private static final String URL = "samplelink";
> private static final String ICON = "system-log-out.png";
>
> public static ManagedLink getInstance()
> {
> List<ManagementLink> list =
> Jenkins.getInstance().getManagementLinks();
> for (ManagementLink link : list)
> {
> if (link instanceof ManagedLink)
> {
> instance = (ManagedLink)link;
> break;
> }
> }
> return instance;
> }
>
> @Override
> public String getIconFileName()
> {
> return ICON;
> }
>
> @Override
> public String getDisplayName()
> {
> return "ManagedLink";
> }
>
> @Override
> public String getUrlName()
> {
> return URL;
> }
>
> @Override
> public String getDescription()
> {
> return "Demo For Problem";
> }
>
> @Override
> public Permission getRequiredPermission() {
> return Jenkins.ADMINISTER;
> }
>
> Queue.Item[] getQueueItems()
> {
> if (items == null)
> {
> items = Queue.getInstance().getItems();
> }
> return items;
> }
>
> public synchronized void doIndex(StaplerRequest req, StaplerResponse
> rsp) throws IOException
> {
> Jenkins.getInstance().checkPermission(getRequiredPermission());
>
> items = Queue.getInstance().getItems();
> logger.info("Queue length in doIndex: " + items.length);
> queue = Queue.getInstance();
>
> ExecutorService service = Executors.newSingleThreadExecutor();
> service.submit(new MyRunner());
>
> rsp.sendRedirect2(req.getContextPath() + "/manage");
> }
>
> class MyRunner implements Runnable
> {
> @Override
> public void run()
> {
> logger.info("Queue length in Runnable from queue object from
> doIndex: " + queue.getItems().length);
> logger.info("Queue length in Runnable with direct access to
> Queue: "
> + Queue.getInstance().getItems().length);
> logger.info("Queue length in Runnable with instance variable
> direct access : " + items.length);
> logger.info("Queue length in Runnable with instance variable
> via method : "
> + ManagedLink.getInstance().getQueueItems().length);
> }
> }
> }
>
> Running this code in Jenkins on Windows, when there are entries in the
> queue, I get the expected length.
> But when I run this code inside my Linux VM, the Queue object is returning
> 0 for the length:
>
> Feb 05, 2017 12:16:02 AM INFO ManagedLink doIndex
> Queue length in doIndex: 1
> Feb 05, 2017 12:16:02 AM INFO ManagedLink$MyRunner run
> Queue length in Runnable from queue object from doIndex: 0
> Feb 05, 2017 12:16:02 AM INFO ManagedLink$MyRunner run
> Queue length in Runnable with direct access to Queue: 0
> Feb 05, 2017 12:16:02 AM INFO ManagedLink$MyRunner run
> Queue length in Runnable with instance variable direct access : 1
> Feb 05, 2017 12:16:02 AM INFO ManagedLink$MyRunner run
> Queue length in Runnable with instance variable via method : 1
>
>
> Strange thing is as well that when I run unit tests on Linux, it works
> fine.
>
> This happens on latest 2.32.2 Jenkins with openjdk 8 on Opensuse but I can
> also observe this with a 1.609.3 Jenkins running with SAP JDK8
> On Windows running with the JDK that comes with the Jenkins installer
> (java 8).
>
> Anyone has an idea what could be the reason for this?
>
> Regards
> Markus
>
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