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https://issues.apache.org/jira/browse/NETBEANS-2291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16798543#comment-16798543
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TLX commented on NETBEANS-2291:
-------------------------------
[~arren]:
bq. The thing I don't have, when NB spends a couple of hours in the reference
queue daemon refreshing file objects, is what files it thinks it's refreshing.
You can probably find out using a heap dump. A heap dump from more recent
versions includes a thread drump where you can see which local variables are
being used in each stack frame in each thread and what these variables contain.
Under normal circumstances this is enough to guess what NetBeans is doing
there. If you're not sure enough, you can also check the NetBeans source code.
I'm not trying to assign work here, but performance problems are typically hard
to debug if you don't have them on your development system. By diagnosing and
pinpointing the problem further in person you might be a great help to the
developers.
By the way: In the past I also debugged into NetBeans successfully. Clone the
whole source code (this part took over an hour because the history is A LOT),
open modules you want to debug into in a NetBeans instance in a VM, start your
slow NetBeans in debug mode, connect to it from the NetBeans in the VM, and
trace what's going on.
> NetBeans is unusably slow
> -------------------------
>
> Key: NETBEANS-2291
> URL: https://issues.apache.org/jira/browse/NETBEANS-2291
> Project: NetBeans
> Issue Type: Bug
> Affects Versions: 8.2, 10.0
> Environment: Ubuntu 18.10
> Linux 4.18.0
> 12 core Xeon E-2176M with 64Gb RAM
> -Xmx2536m (2.5Gb for NB, of which it uses about 1.7G)
> NetBeans 10vc2, 10vc5, 8.2
> JDK 11.0.1
> G1GC, CMS GC, Serial GC
> Reporter: Shevek
> Priority: Critical
> Labels: performance, usability
> Attachments: open-file-slow-01.txt.tdump,
> open-file-slow-02.txt.tdump, open-file-slow-03.txt.tdump, slow-stack-00.txt
>
>
> I used to use NetBeans 8 on JDK8, it was tolerable, but slow.
> Now I have a new laptop, I've tried nb8, nb10 on jdk8, jdk11, with g1gc,
> cmsgc, other gc. They are all UNUSABLY slow. By which I mean, it takes over a
> minute just to open a file.
> Mostly this is because things are waiting for things waiting for very
> inefficiently implemnted file I/O, editor parsing, or things like that. I've
> watched a 12-core Xeon chip spend over 4 hours just attempting to handle the
> Active Reference Queue Daemon thread.
> The slowdown is somewhat incremental - I can escape it as long as I'm happy
> to restart NetBeans every hour or so (which I'm not happy to do).
> Attached a stack dump to get you started, this took over a minute to open a
> 284-line Java file from idle.
> Please feel free to ask all the obvious questions, although I'm fairly sure
> all the obvious things have been done. Mostly, I've got GC down to a
> negligible amount.
> If there's one or more features of NetBeans I can disable to get acceptable
> behaviour while still being able to realistically edit Java code, please tell
> me and I will disable them because I am at the end of my rope after using
> (and developing for) NetBeans for nearly 10 years. If I can get IntelliJ to
> load a Java/Gradle project neatly before this gets fixed, I'm gone.
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