Websocket blocks after terminating without unsubscribing

[samuel-tay]

Describe the bug
As discussed on Discord https://discord.com/channels/783264383978569728/783264902613565450/907267013028749322

It was discovered that subscribing to WS works.

However, if a subscription is not unsubscribed and the session is terminated, then the WS blocks up and no further requests will be entertained. It doesn't help to reconnect and unsubscribe.

Also, in the instance where 2 clients are connected and if Client A terminates the session without unsubscribing, Client B blocks as well, and the whole WS blocks.

To Reproduce
Steps to reproduce the behavior:

1. Have a local node running
2. On CLI wscat -c ws://localhost:8546 (response connected)
3. {"jsonrpc":"2.0", "id": 1, "method": "eth_subscribe", "params": ["newPendingTransactions"]} (respond with suscription id)
4. Ctrl+C to force exit
5. Repeat 2-3, no response in step 3
6. Restart node
7. Repeat steps 2-3
8. {"id": 1, "method": "eth_unsubscribe", "params": ["(subscriptionid)"]}
9. Ctrl+C to exit.
10. Repeat steps 2-3, subscription works

Expected behavior
WS should handle disconnection without blocking.

Screenshots
NA

Desktop (please complete the following information):
Node is Linux

[tomtau]

this is more likely an issue on Ethermint, I assume: https://github.com/tharsis/ethermint/issues/new?assignees=&labels=&template=bug-report.md
@thomas-nguy @yihuang

[odeke-em]

@yihuang and @thomas-nguy I found the cause of the issue in Ethermint per evmos/ethermint#821 (comment) and it comes from a sync.RWMutex .Lock() being invoked before a .Runlock() is invoked and Go's docs for sync.RWMutex explicitly call out this problem per https://pkg.go.dev/sync#RWMutex

It'll be fixed shortly in Ethermint.

[odeke-em]

The fixing PR got merged per evmos/ethermint#933 Can we please close this issue?

[samuel-tay]

Thanks for this! @odeke-em

[odeke-em]

Thanks for this! @odeke-em

Cheers, and thank you @samuel-tay!