Topic: Pool Hopping: The SIMPLE Solution! - page 3. (Read 7909 times)

As it is STILL a proportional system, as soon as some shares are predictably worth more than others (in a 20 minutes sliding window that is restarted at each found block, every share in the first 20 minutes is worth more than any other share later in that round - the only difference is that later on you get 0 instead of a smaller payout) you can very likely (ab-)use this to your advantage.

Anyways:
This method is still unfair (in the sense of: creating massive variance) to users that mine irregularly compared to a PPS system. As difficulty is changing, even by the "law of large numbers" you might run into situations where a high variance kills a LOT of your reward(s) and you'll never be able to make up for it.

This is not true. While in a very short round the shares are worth more than others, it does not make it possible to pool hop.

Let's say a hopper jumps into a pool just after it's found a block in the hope it will find the next one quicker than the time period that payout shares are to be collected over. Let's say this share counting window is 20 minutes, and the hopper only stays in the pool for the first 10 minutes. He then jumps to the next pool in the hope that the previous pool now finds the share in less than 20 minutes so that each share he submitted is worth more. If this happens then the hopper has profited. If this doesn't happen and the round lasts any longer than 30 minutes then the hopper earns absolutely nothing from that pool that he spent 10 minutes in as the payout share collecting window is sliding with the length of time of the round.

Earning more per share in the shorter rounds vs maybe earning absolutely nothing in the longer rounds (for a hopper) should tend to even out over a long period of time by the law of large numbers meaning that hoppers earn exactly the same as non hoppers, only with greater variance.

Exactly, so Pool hopping could be still worth it, as there are SOME shares that are then worth far more than others.

If you consider shares across "rounds" this might help though.

(1000 shares submitted for the first block, 100 for the second block --> look at the last 500 shares of the first block for payout there and the last 400 of the first block and 100 of the second block for the payout of the second one).
I'm not sure if this stays fair if difficulty changes though.

Also as jjiimm_64 said: if you can't mine 24/7 reliably such a pool is not good to use at all compared to a PPS one.

A pool that is averaging many hours per block will also have a time window for shares which is several hours long.

Conversely to what you said, what about when a pool has been working for x hours on a long block and you join the pool right before they find it. You're then getting paid out a larger proportion to what you submitted the whole round. These possible situations average out exactly over a long period of time.

Like I said in the OP, non 24-7 miners would see a much larger variance in their payouts; both up and down. It will tend to even out over a long period of time by the law of large numbers.

...
what about the miners that work for x hours on a long block....  take the miners offline to do. well whatever we do when we take a miner offline..  then all the work that was done would be lost....  I am not going to use a pool that would do that.

Obviously all the shares would be counted.  It only takes affect when the time is greater than "N".  The pool would drop the shares submitted prior to "N" from consideration after "N" is reached.

What do you do on very short (30 second) rounds then, then the number "N" has not yet been reached?

Don't be ! It's arguable an obscure method indeed, since it's not used in any pool at the moment.

You can see PPLNS in action (from a hopper's POV or a regular miner's POV) on this page : http://eligius.st/~luke-jr/samples/800MH/

Ah, so I have. Sorry about that .

I was going off the methods I saw here https://en.bitcoin.it/wiki/Comparison_of_mining_pools and a fairly brief forum search.

Congratulations, you just pretty much reinvented PPLNS (Pay-Per-Last-N-Shares).

Edit: Ok, so it seems that something similar to this already exists: PPLNS. My bad.

While I'm not fundamentally against pool hopping as I believe people should use whatever legitimate advantages that they can to their favour, I think it will become a problem in the future for anybody not hopping. I envisage the future of mining containing a small number of individuals or small groups with large hashing power. For instance, 10% of the miners with 90% of the total hashing power. It would be in their best interests to pool hop to maximise their earnings, and would make it more difficult for smaller players who don't hop.

My simple solution? Calculate payouts based on the fraction of submitted shares submitted during a time window just before finding a block.

For instance, let's say there's a fairly large pool which has the hashing power to average one block per hour. Pool hoppers would be jumping out of the pool after the round has latest longer than 43.5% of the expected shares (reference here: https://forum.bitcoin.org/index.php?topic=3165.0) which is about 25 minutes for our "60 minute average block time" pool. My proposal to this pool to prevent hopping would be to calculate payout based on the 20 minutes (or less) before the block was found. Let's say the pool finds a block at 08:43. Payout would be calculated on the shares submitted between 08:23 and the share that found the block.

Because every share has an equal chance of finding a block as any other share, the miner does not know where this "20 minute" period will be. This "20 minute period" should be a representative sample of each miner's effort to find each block.

The size of the window in which payout is calculated should be decided on a pool-by-pool bases depending on the hashing power of the pool. It should be less than the time it takes for 43.5% of the average number of shares per round to be submitted. For instance, Deepbit might use a 10 minute window. Obviously, payouts for rounds which are shorter than this time period would be calculated from the full round length.

The only disadvantage I see is slightly more variance for non 24-7 miners and low power miners (such as CPU miners), especially on the smaller pools with longer rounds.

Update: The above (the strikethrough text) has been decided to be slightly incorrect (see future posts). Block finding boundaries must be crossed to prevent hopping and the 43.5% rule does not matter. For instance, if the "window" is 60 minutes and the pool finds blocks in less than that time, some shares must be paid out for more than once, with each payment in proportion to the amount number of shares in total in the "window". The length of the window therefore does not matter, provided round boundaries are crossed meaning 24 hour windows are possible in theory to reduce variance on smaller pools.