Dec 4, 2017
Qtum Mainnet Results Nov 27 — Dec 3
Here is the weekly chart review of Qtum Mainnet performance, with the Big Five Network Weight calculation (21.03 million) and an educational feature on orphan blocks.
This week we have the usual charts and graphs showing mainnet performance. The educational feature takes a look at a more obscure topic: if you hang out around blockchains long enough, you will hear about orphaned or stale blocks, and there are some implications for Qtum stakers.
I am an independent researcher, not affiliated with the Qtum Team, but appreciate their advice and the robust technical discussions in the community.
Charts and Graphs
Data sources for this review of the Qtum mainnet performance come from the Qtum Explorer, the blockchain, and logging from the qtumd server application.
Unique Reward Addresses
This week larger wallets continued their hard work securing the network and collecting all those block rewards. Unique addresses per day dropped to 242 on November 28, but this parameter seems to be stabilizing. For the entire week, there were 899 unique addresses, vs. 978 last week. This weekly number continues to drop with more big wallets staking.
Wallets winning multiple blocks per day held steady compared to last week.
Active Transactions per Day
Active transactions per day held steady in the 3,000 to 4,000 range. Active transactions reports transactions for coins and contracts above the baseline two for each block (the coinstake and coinbase transactions).
You can also see transaction charts at Qtum Explorer and QTUM Explorer.io.
Block Spacing Variation
From November 28 to December 3 there were 3 blocks with more than 20-minute spacing (vs. 4 last week), with the greatest spacing for block 56,625 at 23:25. These long blocks are caused by the randomness of the SHA-256 hash algorithm that is used for choosing block rewards. Average block time was stable at 144 seconds.
Network Weight
My alternate approach for the network weight calculation worked well this week with the “big five” wallets maintaining their balances. For the past 7 days, this group (fyRy, atov, 7gRT, S9cx, and xUxY) collected 1,026 block rewards, which for an average 600 blocks per day represents 24.43% of the available blocks. With their total balance of 5.137 million coins this gives a BFNW (Big Five Network Weight) of:
I see our old friend, the wallet calculation of Network Weight, varied from 12 million to 22 million on Sunday, and I suggest you continue to ignore this calculation.
Dude, Where’s my Block Reward?
This week the educational feature considers orphan blocks, with a comparison to bitcoin and Blackcoin orphan blocks (that work the same as Qtum) and Ethereum uncle blocks (that work a little differently). These blocks are technically “stale blocks”, but they are widely called “orphans”, so we will use that term here.
Harking back to my previous ELI5 story comparing SHA-256 hash mining to a footrace, orphan blocks are what you get when two racers (two wallets) both yell “I won!” at the same time (both wallets have a valid SHA-256 solution). What then?
Your author has not experienced an orphan block, but this topic did show up on the old QtumNexus Slack, as a now-you-see-it-now-you-don’t issue with block rewards.
Let’s start by considering the nature of distributed peer-to-peer mining by full nodes (wallets) for a generic cryptocurrency. All these wallets are working hard (for Qtum, not so hard) to solve the SHA-256 hash algorithm and win the next block reward. It is inevitable that occasionally two wallets will simultaneously solve for the next block, and both think they will get the block reward.
In this case, both wallets sweep up all the recent unconfirmed transactions into a block and publish that block to the blockchain. Actually, the new blocks go into the memory pool maintained by each wallet. Your correspondent is not a blockchain engineer, so perhaps someone will correct me, but I visualize the memory pool like a swimming pool with all the recent unconfirmed transactions and these blocks sloshing around, and the wallet taking a big net, fishing out and processing the transactions and blocks (forming the longest, most difficult chain by adjusting the top of the blockchain using functions like MemoryTip, DisconnectTip, ConnectTip, etc.).
Bitcoin, Blackcoin Orphan Blocks
With that generic introduction, let’s see how the bitcoin and Blackcoin handle orphan blocks.
Bitcoin, Blackcoin, and Qtum treat orphan blocks the same way: they are abandoned and never recorded in the permanent blockchain ledger. For bitcoin, blockchain.info shows a nice visualization of orphan blocks, as a growing height blockchain with the orphan blocks connected off to the side, then abandoned. Below bitcoin block 497373 is mined by both AntPool and SlushPool, but you can see that the bitcoin wallets decided that the SlushPool block would make a weaker blockchain, so SlushPool’s block (the orphan block) is unceremoniously dropped (and SlushPool misses out on that 12.5 BTC — USD 145,000 block reward — ouch!).
This handling of the orphans is perfectly normal, perfectly healthy, and if you think about it for a moment, Satoshi had to design a mechanism like this to handle the orphans, which are inevitable in a peer-to-peer mining network. Bitcoin has several orphan blocks a day, a few percent.
Blackcoin is the closest corollary to the Qtum blockchain (they both share Proof of Stake v3.0 mining algorithm). Blackcoin orphan blocks are charted here.
According to this chart, Blackcoin averages about 40 orphan blocks a day or a few percent.
Ethereum Uncles
Ethereum calls the orphan blocks uncles, and treats them a little better — better to be an uncle than an orphan, even if you are that crazy uncle like Uncle Fester.
Vitalik wanted to incentivize miners to find and publish uncles. In Ethereum a block reward is paid for uncles. Currently, Ethereum pays 3 ETH per block reward, and 7/8 of that for uncles (if you are pool mining for Ethereum, make sure the pool is paying out for the uncles). Ethereum’s handling of orphans using the GHOST (Greedy Heaviest Observed Subtree) approach adds the uncles to the blockchain.
Here is a nice video explanation All About Ethereum Uncles.
Here is a chart showing Ethereum uncles. For Ethereum, the quantity of uncles per day (miners are incentivized to find and report them) is about 11% of the main chain blocks per day.
Qtum Orphan Blocks
I have not personally seen an orphan block created from a block reward, but believe the symptoms are that you would see the initial block reward transaction in your wallet, that transaction would not show any confirmations or increasing confirmations, and the transaction hash would not be searchable in the blockchain explorer (because the transaction doesn’t make it onto the blockchain). It is as if your block reward, and the related block your wallet sent to the network, never happened, and the block reward will disappear from your wallet when the wallet figures this out. It is best to wait for 6 confirmations before you are certain your block reward will stick.
I would love to show you some charts about Qtum orphan blocks, but so far no one has implemented an orphan block viewer for Qtum (hint, hint), and I think it would involve real-time monitoring of the memory pool to identify and track the orphan blocks. I would guess that Qtum orphan blocks are similar to bitcoin and Blackcoin, with a few percent per day, say 10 to 15 orphan blocks per day.
From that old Slack thread, the stale blocks (orphans) leave a message in the wallet debug.log file like this:
But you are unlikely to see this message unless you are a Qtum whale. In any case, orphan blocks are perfectly normal, perfectly healthy, and I hope this explanation will help you understand them.
Patrick was in Hong Kong last week, but I doubt he had time for any sightseeing with his busy schedule. We will end with a visit to Lantau Island, near Hong Kong. The biggest thing on Lantau Island is the “Big Buddha”, one of the world’s largest Buddha statues. Here is a tasty drone flight and some blogs (1 2) about Tian Tan (Alter of Heaven) Big Buddha at Po Lin Monastery.
Hoping you have a big flight of block rewards,
JB395
I couldn’t resist sharing one more photo from Hong Kong, because your correspondent will never get tired of photographing the evening lights reflecting off Victoria Bay:
