Re: [platform-core-dev] debugging blocking jobs

[John Arthorne <John_Arthorne@xxxxxxxxxx>]

I can't think of anything offhand without
having access to the VM running the problem. I does not look familiar to
me. It could be as Brian said that there is a corruption in the data structure
leading to an infinite loop, although I have never seen this before. Another
possibility is that there is a blockage causing a massive backlog of queued
jobs that is causing freezing. The code path in the first thread is when
a job is queued to run, but then there is some currently running job with
a conflicting scheduling rule that it needs to queue behind. There are
some debug flags for logging job events but it is extremely verbose. It
is useful when you have a very specific set of steps to reproduce a problem,
and you know the time range to look in:

# Prints debug information
on running background jobs
org.eclipse.core.jobs/jobs=true
# Includes current date and
time in job debug information
org.eclipse.core.jobs/jobs/timing=true

It may not help in this case, but in Mars
stream support has been added to dynamically turn this tracing on or off
from the tracing preference page.

John




From:      
 Martin Lippert <mlippert@xxxxxxxxx>
To:      
 platform-core-dev@xxxxxxxxxxx,

Date:      
 09/22/2014 10:39 AM
Subject:    
   [platform-core-dev]
debugging blocking jobs
Sent by:    
   platform-core-dev-bounces@xxxxxxxxxxx

---

Hey!

I have a question around debugging problems with jobs. I got a number of
thread dumps from users reporting freezes in Eclipse/STS, but I have difficulties
identifying the issue from looking at the thread dumps and I wonder if
you have an idea how to investigate those issues.

Suspicious (to me) is that there is a thread in this state:

"Worker-343" prio=6 tid=0x000000002d791800 nid=0x19cc runnable
[0x0000000039dbf000]
   java.lang.Thread.State: RUNNABLE
                
at org.eclipse.core.internal.jobs.InternalJob.addLast(InternalJob.java:171)
                
at org.eclipse.core.internal.jobs.JobManager.nextJob(JobManager.java:1025)
                
- locked <0x00000005f0191fb8> (a java.lang.Object)
                
at org.eclipse.core.internal.jobs.JobManager.startJob(JobManager.java:1519)
                
at org.eclipse.core.internal.jobs.WorkerPool.startJob(WorkerPool.java:221)
                
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:51)

   Locked ownable synchronizers:
                
- None

While other threads are blocked because of this lock (for example the main
UI thread):

"main" prio=6 tid=0x0000000002bcd800 nid=0x2284 waiting for monitor
entry [0x000000000012e000]
   java.lang.Thread.State: BLOCKED (on object monitor)
                
at org.eclipse.core.internal.jobs.JobManager.doSchedule(JobManager.java:532)
                
- waiting to lock <0x00000005f0191fb8> (a java.lang.Object)
                
at org.eclipse.core.internal.jobs.JobManager.schedule(JobManager.java:1161)
                
at org.eclipse.core.internal.jobs.InternalJob.schedule(InternalJob.java:430)
                
at org.eclipse.core.runtime.jobs.Job.schedule(Job.java:500)
                
at org.eclipse.ui.internal.navigator.actions.LinkEditorAction.activateEditor(LinkEditorAction.java:225)


However, I have no idea how to find out that is really going on here. I
there a good way to analyze this?

Thanks a lot for your help!
-Martin


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