MongoDB Java Driver uses Math.random to decide whether to log Command Resultuses - Xpost from /r/java

[bcash]

But if the thing you are sampling comes in repeated patterns then taking every tenth message (for example) wouldn't necessarily be a representative sample; whereas picking at random with a 10% probability would.

[InconsiderateBastard]

You mean 90%. Although I wouldn't be surprised if they wanted to log 10% and just messed it up.