Network issues with testnet caused by lack of blocks

[pinheadmz]

I'm not sure if we need to try to solve these issues with code (the solution would be something like adding if (testnet) everywhere or modifying the common if (!this.syncing)) but I wanted to document since I suspect it could be a FAQ:

hsd thinks it is "syncing" (i.e. initial block download)

The main culprit here is that the last block is over 40 minutes old. There are no checkpoints and the minimum chain work is 0. Once a node has switched synced to true, it is mostly latched until restart, meaning this is a particular problem for new nodes on testnet.

hsd/lib/blockchain/chain.js

Lines 2701 to 2718 in 61defcc

	maybeSync() {
	if (this.synced)
	return;
	if (this.options.checkpoints) {
	if (this.height < this.network.lastCheckpoint)
	return;
	}
	if (!this.hasChainwork())
	return;
	if (this.tip.time < this.network.now() - this.network.block.maxTipAge)
	return;
	this.synced = true;
	this.emit('full');
	}

Node behavior when syncing is true

• No peers are syncable (allowed to be synced from) except the loader peer, which must be an outbound connection. Therefore if you connect to Alice's node and mine a block, Alice will not accept it because Alice is "syncing" and you are not her loader peer.

• Peers send getblocks, receive nothing in response, timeout after 30 seconds, and disconnect... repeatedly. Since we think we are syncing we expect peers to have blocks for us. They don't. One possible solution for this is to send empty INV messages back if there are no blocks in the chain following the requesting peer's getblocks stop

[pinheadmz]

This also blocks rpc getblocktemplate, making mining impossible, meaning testnet can't really proceed at all. I'm trying to CPU mine with hsd by itself just to hopefully get one block added to the chain so it thinks its "synced" and start generating block templates for hs-miner:

hsd/lib/node/rpc.js

Lines 1347 to 1350 in 9d21a04

	if (!this.chain.synced) {
	throw new RPCError(errs.CLIENT_IN_INITIAL_DOWNLOAD,
	'Node is downloading blocks...');
	}