Question: All lines in my AppStats look like this: `real=19ms cpu=0ms api=0ms overhead=0ms`, it has the correct real time, but the other values are always 0. Anyone have this problem before or know how to fix this?

Answer: 
It's a convention, but a particularly useful one when you think about it. In general, if a program succeeds that's all you need to know. If it fails, however, you might need to know all kinds of information about the failure - why it happened, how to fix it, etc. Having zero mean 'success' and non-zero mean failure lets you can check pretty easily for success, and investigate the particular error for more details if you want to. A lot of APIs and frameworks have a similar convention - functions that succeed return 0 and and those that fail give back an error code describing the particular failure case.
AFAIK this come from the C convention that you should return 0 if succeded.
See:

```
man close

```

Most of the C (POSIX) api is build like this.
<http://en.wikipedia.org/wiki/C_POSIX_library>