What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind bug

What does this PR do / why do we need it:
True value数量大于count时，之前版本永远只选择前count个true value的samples。修改后sample所有的true value，之后随机选择count个samples。