RFR: 6364: Improvements to the Thread Graph

[Alex Macdonald]

On Sun, 30 Aug 2020 13:12:29 GMT, Brice Dutheil <github.com+803621+bric3 at openjdk.org> wrote:

>> Hi, I noticed that when selecting a part of thread lane, like an event, then the cell/label is half dimed :
>> 
>> <img width="797" alt="JFR thread top half"
>> src="https://user-images.githubusercontent.com/803621/91659293-3665ea00-eacf-11ea-9fa7-0b86db536590.png"> <img
>> width="684" alt="JFR thread bottom half"
>> src="https://user-images.githubusercontent.com/803621/91659298-37971700-eacf-11ea-8c53-d99cf9e1f4ea.png">
>
> I also noticed that the overview mode indicates "too much content", for recording of applications having a high number
> of threads. And when the display area is not big enough, e.g. on 13 inches laptop or when the thread table is expanded.
>  
> ![too much content on overview, thread table
> expanded](https://user-images.githubusercontent.com/803621/91659801-7a0e2300-ead2-11ea-911b-ebf4e79d3228.png)
> ![overview ok, external screen, thread table
> hidden](https://user-images.githubusercontent.com/803621/91659799-72e71500-ead2-11ea-8ebf-7433031fae2b.png)
> _Of course the application has a design issue (with this manyfold threads) but the point remain in my opinion._
> 
> The new view works great otherwise.
> 
> I'll be happy to sharemy private startup and continuous JFR files if needed. Here's those of JMC when I took these
> snapshots. [startup-thread-view.zip](https://github.com/openjdk/jmc/files/5146861/startup-thread-view.zip)

Hi @bric3! Thanks for taking a look at this PR and providing your feedback, the screenshots and jfr files you attached
were also very much appreciated!

> Hi, I noticed that when selecting a part of thread lane, like an event, then the cell/label is half dimed :

Good find, I'll poke around and see what I can do to get that to highlight the rest of the lane name.

> I also noticed that the overview mode indicates "too much content", for recording of applications having a high number
> of threads. And when the display area is not big enough, e.g. on 13 inches laptop or when the thread table is expanded.

Thanks for finding this and sharing your jfr file too. I'll have to poke around with some different screen sizes and
see what adjustments can be made here. The "too much content" overlay happens to the current threads page lanes under
size restrictions, it looks like having the table above the chart causes it to reach this state a bit earlier than
before.

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PR: https://git.openjdk.java.net/jmc/pull/27