user91708: Do the notifications from walletnotify and blocknotify are sent during the wallet synchronization or at the end? Say the wallet was offline for 100 blocks and when started: will it send the notifications after the each block it downloads and verifies and so all the relevant transactions in them or will it send them at the end? I would assume it sends them as it gets them, so then how would I resolve these properly if all the incoming request at that time are blocked?

user3697: Refers to Bitcoin Core 0.17:
WalletNotify
Will be executed at the time when a transaction gets added to the wallet. If your wallet is 100 blocks behind and in those 100 blocks you have 2 transaction in each block, the wallet notify script will be called twice per block (== 200 executions during the 100 block catch up).
Only valid blocks (valid transaction) will result in a wallet-notify call.
Will also be called when a mempool transactions (unconfirmed transaction) was added to the wallet (and therefore relevant to the wallet)
BlockNotify
Will be executed when a block gets connected to the active chain and before WalletNotify.
Consider taking a closer look at Bitcoin Cores ZMQ API that allows more efficient process interaction (wallet/block notify spawn a process on each call).

91708: <p>Do the notifications from walletnotify and blocknotify are sent during the wallet synchronization or at the end? Say the wallet was offline for 100 blocks and when started: will it send the notifications after the each block it downloads and verifies and so all the relevant transactions in them or will it send them at the end? I would assume it sends them as it gets them, so then how would I resolve these properly if all the incoming request at that time are blocked?</p>
 3697: <p>Refers to Bitcoin Core 0.17:</p>

<h2>WalletNotify</h2>

<p>Will be executed at the time when a transaction gets added to the wallet. If your wallet is 100 blocks behind and in those 100 blocks you have 2 transaction in each block, the wallet notify script will be called twice per block (== 200 executions during the 100 block catch up).</p>

<p>Only valid blocks (valid transaction) will result in a wallet-notify call.</p>

<p>Will also be called when a <strong>mempool transactions</strong> (unconfirmed transaction) was added to the wallet (and therefore relevant to the wallet)</p>

<h2>BlockNotify</h2>

<p>Will be executed when a block gets connected to the active chain and before <code>WalletNotify</code>.</p>

<p>Consider taking a closer look at <strong>Bitcoin Cores ZMQ</strong> API that allows more efficient process interaction (wallet/block notify spawn a process on each call).</p>
