Review request for JMC-4645: Add size distribution chart to IO Pages

Alex Macdonald almacdon at
Fri Apr 5 18:36:21 UTC 2019

Hi Ken,

On Fri, Mar 29, 2019 at 4:08 PM Ken Dobson <kdobson at> wrote:

> Hi all,
> Please review this patch I've made that adds a size distribution chart to
> the IO Pages.
> Bug:
> Webrev:

Overall the code looks good from what I can tell.

Having said that, I just want to confirm what I'm reading off the chart,
let's use this sample screen shot [0] ( as an
example. The y-axis displays the number of reads/writes, and the x-axis
displays the size of that read or write? If that's the case I'm a bit
confused. The blue bar (write) hits 1 on the y axis for 1 read, and is
displayed at ~6.16KiB on the x axis because that's how much it wrote.
However, the red bar (read) hits 1797 on the y axis for 1797 reads as
expected, but why does the x axis display 0 - 256B when there was 1.89 KiB
read in total?

A couple of formatting nits:

1. There are some unused imports in the DataPageToolkit

+import org.openjdk.jmc.flightrecorder.ui.PageManager;
+import org.openjdk.jmc.flightrecorder.ui.pages.itemhandler.ItemHandlerPage;+import

2. Excess white space just before (and inside)
3. JDKAttributes, SocketIO & FileIO pages also each have a few instances of
excess/trailing white space

> Thanks,
> Ken Dobson




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