default value of auto-compaction in 3.2.x

[shsjshentao]

In document, i find the default value of auto-compaction is 0. It seems to mean no compact.
But in fact, i find etcd will compact every 5 minutes if i do not set this flag.
Is it a bug in 3.2?
Is it related to #8098?

[hexfusion]

In document, i find the default value of auto-compaction is 0.

HI @shsjshentao which document are you referring to?

[gyuho]

etcd will compact every 5 minutes

How do you know? Do you have server logs?

[yudai]

I think it's due to #9443.
Since last is not updated, every iteration of timeout triggers auto compaction.

[hexfusion]

Not to hijack the issue but I do see this constant. How does this fit into the picture?

https://github.com/coreos/etcd/blob/5b9741e804a44990f67b5eeab686b7141a801346/compactor/compactor.go#L32

I guess every 5 mins would cause timeout/compact @yudai ?

[yudai]

The value @hexfusion pointed out is used here to set timeout in the loop:

https://github.com/coreos/etcd/blob/5b9741e804a44990f67b5eeab686b7141a801346/compactor/periodic.go#L72

and as mentioned in #9443, last is not updated at all, so this condition is pass through;

https://github.com/coreos/etcd/blob/5b9741e804a44990f67b5eeab686b7141a801346/compactor/periodic.go#L80

Eventually, every 5 minutes, auto compaction happens without checking the last execution time.

[hexfusion]

@shsjshentao after @yudai explanation I feel this is a duplicate of #9443. Please track this issue for updates.

[gyuho]

@shsjshentao If you set auto compaction 0, compactor wouldn't even run. What's the server log?

[yudai]

Oh that's true. I think I jumped into a wrong way. Sorry for that.
The revision based compactor referenced by #8098 is not included in 3.2.x. So it should be not related.

What I came up with 5 minutes around compactor is checkCompactionInterval . However, I double checked the code and 3.2.x doesn't have the same issue referenced by #9443. Moreover, as @gyuho mentioned, if you do not provide a value to the flag, the compactor itself should not run at all.

https://github.com/coreos/etcd/blob/c8cfdb3b558f758367b8f0c4566fce88b56c9aec/etcdserver/server.go#L489-L495