Fix units for some metrics

[kittylyst]

Description:

I noticed that some of our units in the jfr-streaming module are not quite correct. I have made them be correct, but I don't know if all of the units I've defined (e.g. Hz) are actually used in OpenTelemetry.

Testing:

Manual test of each JFR event that the code responds to.

[jonatan-ivanov]

I have a related question for this (but not necessarily strictly the subject of this PR).

Is kB and MB are actually KiB and MiB?
See kibibyte vs. kilobyte: https://en.wikipedia.org/wiki/Byte#Multiple-byte_units

1kB  == 1000B
1KiB == 1024B

If they are KiB/MiB, I would either change them or add some javadoc here that kB and MB are based on powers of 2 not 10 because based on the international standards 1kB is based on powers of 10).

[kittylyst]

They are actually KiB and MiB. This event:

jdk.GCHeapSummary {
  startTime = 11:51:47.587
  gcId = 685
  when = "After GC"
  heapSpace = {
    start = 0x7C0000000
    committedEnd = 0x7D9300000
    committedSize = 403.0 MB
    reservedEnd = 0x800000000
    reservedSize = 1.0 GB
  }
  heapUsed = 155.7 MB
}

is actually

Used: 163273232

when read as a raw long (which actually returns bytes), and so:

jshell> 155.7 * 1024 * 1024
$2 ==> 1.632632832E8

I'll fix this - looks like we should use bytes everywhere and format for display.

[trask]

looks like we should use bytes everywhere and format for display

👍