Graceful Stop

[bosnet]

Graceful Stop

[anarcher]

I will figure out https://github.com/facebookgo/grace and something else. :-)
IMHO, https://github.com/oklog/run can be useful for this purpose.

[anarcher]

"facebookgo/grace" has an interesting feature to restart without dropping any connections.
The working processes are like below:

• Fork a new process which inherits the listening socket.
• the child process performs initialization and starts accepting connections on the socket.
• the child sends a signal to the parent to stop accepting connections and terminate.

That feature looks like great, but we get two node process (old and new) at some time).

I have a question about 'graceful restart' is necessary? Instead, I think 'graceful stop' is necessary.

When a node is terminating, Clean up (disconnecting) network connections and stop terminating and waiting (with timeout) for processing tasks.

What do you think?

[spikeekips]

@anarcher It will be unnecessary for receiving message from client, because it does not need to keep connection, and the other cases like 'event-stream' can be ignored. As you suggested, 'graceful stop' will be good.

[Geod24]

I have a question about 'graceful restart' is necessary? Instead, I think 'graceful stop' is necessary.

I'm wondering that too. I don't see much value in implementing graceful restart in app. Graceful stop is a nice feature though.

[spikeekips]

@anarcher At first, the reason for 'graceful restart' was that the node needed to be restarted to update new version or new validator list, or anything else to be applied new environments.

[anarcher]

I'm wondering that too. I don't see much value in implementing graceful restart in app. Graceful stop is a nice feature though.

@Geod24 I agree with your opinion! :-)

@anarcher At first, the reason for 'graceful restart' was that the node needed to be restarted to update new version or new validator list, or anything else to be applied new environments.

IHMO, 'graceful restart' without dropping any connections (facebookgo/grace) is not suitable for node.

For changing validator list, we should stop and start a node with the new validator CLI arguments.
At some time, If old node process and new node process tries to access same leveldb, one of them get a failure to connect.

I feel safe to stop and start a node but, with graceful stop :-)
So, I would like to change this issues title 'Graceful Stop' :-)