why only bytes-read-rate has value in hot command

[siddontang]

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

run sysbench update_non_index with just only 1 table and 1m rows

» hot store
{
  "bytes-write-rate": {
    "1": 0,
    "4": 0,
    "5": 0
  },
  "bytes-read-rate": {
    "1": 2472,
    "4": 36933,
    "5": 193
  },
  "keys-write-rate": {
    "1": 0,
    "4": 0,
    "5": 0
  },
  "keys-read-rate": {
    "1": 0,
    "4": 0,
    "5": 0
  }
}

2. What did you expect to see?

I think bytes-write-rate should also have value.

Btw, maybe keys-read-rate and keys-write-rate have value too.

3. What did you see instead?

Only bytes-read-rate has value, I am confused about this result.

4. What version of PD are you using (pd-server -V)?

./bin/pd-server -V
Release Version: v3.0.0-beta.1
Git Commit Hash: 57170171811130d7d39759efb9f9677aebfc03db
Git Branch: master
UTC Build Time:  2019-03-27 01:51:58

[rleungx]

Fixed via #1487 and tikv/tikv#4436.