Ensure empty_blocks=false working

[ethanfrey]

Why: To ensure the liveness of the network

Test this and see what we need to adjust

Update (Alex):
This are configuration flags in the <tgrade-home>/config/config.toml file.

# EmptyBlocks mode 
create_empty_blocks = false
# possible interval between empty blocks
create_empty_blocks_interval = "5m"

Watch server logs or server console at port 26557 (default) for blocks created

See setup.sh + start.sh

[pinosu]

@alpe I tested this and empty blocks are created even if :

• create_empty_blocks = false
• create_empty_blocks_interval = "5m"

[pinosu]

I think this is relevant in our case: tendermint/tendermint#1995
Basically if the app hash changes, these flags are not respected and an empty block is created.
This is related to issue #99 . BlockHeaders are tracked all the time but validator sets are always nil

tgrade/x/poe/keeper/historical_info.go

Line 100 in b16f823

var valSet stakingtypes.Validators // not used by IBC so we keep it empty

. This makes the state hash change all the time and that's why empty blocks are created. I tried to make a change in this PR and it actually fixed the issue. @alpe I am not sure it is the right solution, but it might help in future debugging.

[alpe]

This is indeed the issue. For each new block we store the app hash in begin_block (for ibc historical info) which then modifies state to cause the next block to be created. Good digging @pinosu

[ethanfrey]

Very good find as to the cause!

[ethanfrey]

If #99 is solved, should this work? Or is there something else that is updating all the time?

For each new block we store the app hash in begin_block (for ibc historical info)

We store the app hash? Or the validator hash?

[alpe]

Issue #99 should have been closed already. The valset was not persisted with historic information and the app hash is required for IBC.
I can confirm that without the state change due to historic information no empty blocks are created

[alpe]

Some notes from discussions:

• The app hash and some other block header data for the last x blocks are required by the ibc module: https://github.com/cosmos/ibc-go/blob/v3.0.0/modules/core/02-client/keeper/keeper.go#L254-L263
• The valset is not even used there, so we don't store it with the historic information.

Possible solutions:

• Query the tendermint db directly:
  • Problem with prune settings so that not all historic data may be available in vanilla Tendermint
• Non IAVL DB that persists the historic information
  • Can be setup in app.go and passed to the poe begin blocker via context for example.
  • Important to handle cached writes vs committed writes proper