Transactions per second with the Lightning Network?

[Kprawn]

Bitcoin without the Lightning Network gives us more or less 7 transactions per second (tps). Visa averages around 2,000 tps,

with a peak capacity of perhaps 50,000 tps. How are we going to compare transactions per second with systems like this,

when all of those transactions are going to be off-chain? It will still be theoretically be 7+ transactions per second {on-chain}

transactions, with no method to count off-chain transactions? 

[1714122000]

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[1714122000]

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[RGBKey]

There won't be an effective way to count lightning network transactions because transaction information isn't broadcast, only channel updates. Additionally, some channels may not be announced to the network (current phone wallets, private business networks, etc.). However I believe the number of transactions per second should scale up as the network gets larger, more nodes are added and more channels are created.

[aleksej996]

There will be as many transactions as we need, LN isn't really limited in this manner.

The question still only remains on how many on-chain transactions we will need, but we will have to wait to see that.
My guess is, not very much.

[Xynerise]

RGBkey is correct.
Transactions per second is not a valid metric of the Lightning Network because commitment transactions aren't broadcast to the blockchain, just transferred p2p across nodes.
However there are certain factors that can limit this, such as effective routing and channel capacity of the nodes.

[HeRetiK]

Bitcoin without the Lightning Network gives us more or less 7 transactions per second (tps). Visa averages around 2,000 tps,

with a peak capacity of perhaps 50,000 tps. How are we going to compare transactions per second with systems like this,

when all of those transactions are going to be off-chain? It will still be theoretically be 7+ transactions per second {on-chain}

transactions, with no method to count off-chain transactions? 

I guess we'd mostly have to rely on some of the larger merchants to publicize the amount of LN transactions they process each day and go from there. Despite the P2P trade (ie. C2C business) that Bitcoin enables it is fairly save to assume that at least in the forseeable future a significant amount of transactions will go to centralized entities such as exchanges, payment processors and possibly a handful of merchants that accept BTC directly (ie. traditional B2C business). This could provide enough data to extrapolate from there. The reliability and conclusiveness of said data is a different question though.

However I'm not sure if tps is all that meaningful a metric in the case of LN. After all the main challenges that LN will face in terms of scalability will likely largely depend on the payment capacity of each channel. LN may be able to process, say, 500,000 sub-cent transactions per second but only a couple of hundreds tps for everything bigger than USD 50,-. These are random, baseless, speculative examples of course -- point being that we'll probably have to stop thinking in terms of tps when it comes to LN.

So we'll probably have to rely on the following metrics to see the effectiveness of LN's scalability:

1) Network capacity / Channel capacities
2) Amount of on-chain transactions required for closing / opening channels

In the end we'll have to see in practice whether LN scales sufficiently. Especially 2) will be a metric to keep an eye on.


Keep in mind though that LN is not the scaling solutions to end all scaling problems. Any improvements in on-chain scalability will be multiplied by LN. Additional protocol layers inbetween may further improve on LN's scalability.

[DooMAD]

Keep in mind though that LN is not the scaling solutions to end all scaling problems. Any improvements in on-chain scalability will be multiplied by LN. Additional protocol layers inbetween may further improve on LN's scalability.

If we think of Lightning purely in terms of temporarily lifting some BTC off of a single blockchain, shuffling it around a bit with lower fees and then dropping it back down on that same single blockchain, then I can understand why people might see it that way.  But that's not the sole benefit gained from Lightning.  

Over the longer term, I believe, more than ever, that atomic cross-chain transactions (or atomic swaps) will inevitably grow into a scaling solution in its own right.  Any compatible blockchain people perceive to have value will effectively become another transactional layer.  You can elect to use LN as an off-chain layer if you want, or you can use it as a vehicle to reach all the other layers to transact on-chain.

We actually have all the tools we need.  It's just a case of getting people to recognise it and eventually make it simple enough for the average person to use.  Bitcoin will remain the most decentralised and most secure layer, which will underpin all the others.  These other layers will have varying degrees of decentralisation and security depending on the values of the amounts being transacted.  There may even be dedicated specialist layers for things like increased privacy, smart contracts and other uses.  

Some of these layers may indeed end up being recognisable altcoins trading right now.  Atomic swaps from BTC to LTC have already been done on testnet, it's only a matter of time before it happens on mainnet.  For too long we've treated other blockchains as competition.  Something to do battle with in the market.  But maybe we should see them as an opportunity instead.  A chance to create a world where however small the value of your transaction, there will be a block to store it in somewhere within the next few minutes.  And if your transactions grow in value, you can migrate your wealth to more secure blockchains at an affordable cost.  A huge number of transactions per second, just over multiple layers.  All the scalability we could ever require.  Lightning combined with atomic swaps can make all of that happen.

[Kakmakr]

I think this is a very good question, because businesses like to use statistics like this to compare technologies. If I have a business and I have to decide what payment network would be the most efficient to use, then I would want to have the specifications for all of my options.

It is also a great marketing tool for Bitcoin to promote it's use, when we can say that Bitcoin can handle say 100 000 transactions per second, compare to the 50 000 transactions per second that are done by credit card companies.

The open-ended answer to Bitcoin's scalability, will confuse people and they will go for technologies that are measurable. Would you buy a GPU card that can handle say 6000 fps or a GPU card where the fps cannot be determined? How do you sell such a product to people, when it is not measurable or defined?

Interesting conundrum.  ^smile^

[Carlton Banks]

Keep in mind though that LN is not the scaling solutions to end all scaling problems. Any improvements in on-chain scalability will be multiplied by LN. Additional protocol layers inbetween may further improve on LN's scalability.

layers
layers
layers

You can describe different cryptocurrencies with different Blockchains as "layers of the Bitcoin blockchain" as many times as you like (gee, I wonder whether you'll try to repeat this falsehood again in future? :/ ), it will never be true.

In order to be a layer of Bitcoin, a protocol must use valid script of the Bitcoin protocol, and valid/spendable inputs/outputs from the Bitcoin blockchain. Please do not attempt to mislead people with your "undermine Bitcoin by any means necessary" rhetorical tricks, you've been told enough times already.


There would be no point to your scheme anyway, blockchains scale tx throughput badly, adding blockchains to blockchains therefore cannot improve scalability better than simply adding real additional protocol layers to a blockchain (which are not constrained by the same resource costs as the blockchain base layer, hence the orders of magnitude improvement in tx scaling).



The fact that you diverted attention from someone talking about genuine on-chain scaling improvements only serves to highlight the dishonesty of your argument further (which is remarkable considering how dishonest the semantic tricks in the content of your post was)

[DooMAD]

layers
layers
layers

You can describe different cryptocurrencies with different Blockchains as "layers of the Bitcoin blockchain" as many times as you like (gee, I wonder whether you'll try to repeat this falsehood again in future? :/ ), it will never be true.

In order to be a layer of Bitcoin, a protocol must use valid script of the Bitcoin protocol, and valid/spendable inputs/outputs from the Bitcoin blockchain. Please do not attempt to mislead people with your "biggest-blocks by any means necessary" rhetorical tricks, you've been told enough times already.

There would be no point to your scheme anyway, blockchains scale tx throughput badly, adding blockchains therefore cannot improve scalability better than real additional protocol layers (which are not constrained by the same resource costs as the blockchain base layer).

In what way is it my "scheme"?  It's merely a potential future that could unfold.  We all know that none of this is set in stone and the picture in future could look entirely different from what any of us currently imagine.  I just think that if hopping from one blockchain to another becomes a seamless and simple process, the lines may well start to become blurred.  People may stop seeing altcoins as separate entities and it may all just become different denominations of the same money.  By all means continue being the maximalist zealot of the "one true blockchain", but there's little you can do if others see it differently.  You wanted Lightning, this is one of the doors it might open.  Then again, it might not.

Instead, there may be newly created layers that work even better.  Ones that, as you say, utilise spendable inputs and outputs from the base chain.  Hardly anyone seems to be talking about things like sidechains and treechains anymore, so I don't know what work is being done to make them a reality, but those are also a possibility.  Mostly, it's all about network effects and perceived value.  Ultimately, people will use whatever is most convenient and efficient.  If you think my vision of the future is "dangerously wrong", then all I can suggest is that you take some form of action to prevent it happening.  I don't see how you accusing me of being a malicious actor for the thousandth time is going to change anything, though.  

All this sounds just like more of your usual authoritarian rhetoric.  All ideas must be approved and sanctioned by our glorious leaders, right?

They're only ideas, Napoleon.  Take it down a notch.



//EDIT  Okay, you added more while I was replying:

The fact that you diverted attention from someone talking about genuine on-chain scaling improvements only serves to highlight the dishonesty of your argument further (which is remarkable considering how dishonest the semantic tricks in the content of your post was)

HeRetiK is indeed correct to point out that "Any improvements in on-chain scalability will be multiplied by LN", so I'll happily reiterate that point to make sure it isn't lost in the conversation.  

The OP was questioning how we would be able to compare the number of all the off-chain transactions to Visa, so I thought it worthwhile pointing out that Lightning can be used to reach other blockchains where transactions per second could also be measured.  If on-chain capacity is temporarily reached on one chain, it's not beyond the realm of reason to infer people may elect to use a different chain.  I didn't realise that was such an appallingly offencive point to raise.  Sorry if I hurt your delicate sensibilities.  But I'm sure further genuine on-chain scaling improvements will be welcomed by all, myself included, as well.  My comments clearly won't divert attention away from upcoming advancements like Schnorr, AMP, etc.  So we've got all of that to look forward to.  But it's almost flattering you think I'm capable of singlehandedly derailing development like that.  I'll be sure to keep my new-found superpowers in check.  

[Carlton Banks]

DooMAD, I've proven you use deceitful arguments to promote bad ideas before. Where's your proof for any of your claims?

The fact that you're now reduced to using obvious lies ("sidechains are Bitcoin layers", lol) only demonstrates how desperate your position has become.

[HeRetiK]

layers
layers
layers

You can describe different cryptocurrencies with different Blockchains as "layers of the Bitcoin blockchain" as many times as you like (gee, I wonder whether you'll try to repeat this falsehood again in future? :/ ), it will never be true.

In order to be a layer of Bitcoin, a protocol must use valid script of the Bitcoin protocol, and valid/spendable inputs/outputs from the Bitcoin blockchain. Please do not attempt to mislead people with your "biggest-blocks by any means necessary" rhetorical tricks, you've been told enough times already.

There would be no point to your scheme anyway, blockchains scale tx throughput badly, adding blockchains therefore cannot improve scalability better than real additional protocol layers (which are not constrained by the same resource costs as the blockchain base layer).

In what way is it my "scheme"?  It's merely a potential future that could unfold.  We all know that none of this is set in stone and the picture in future could look entirely different from what any of us currently imagine.  I just think that if hopping from one blockchain to another becomes a seamless and simple process, the lines may well start to become blurred.  People may stop seeing altcoins as separate entities and it may all just become different denominations of the same money.  By all means continue being the maximalist zealot of the "one true blockchain", but there's little you can do if others see it differently.  You wanted Lightning, this is one of the doors it might open.  Then again, it might not.

While I'm also excited about the potential applications that atomic cross-chain swaps could enable, I have to agree with Carlton Banks that further improving on-chain scalability by utilizing atomic cross-chain swaps to spread transactions across multiple blockchains -- effectively using it as a load-balancing method of sorts -- is unlikely to come to fruition. I do like your vision of blurred lines between various cryptocurrencies though.

Of course transactions spread across multiple blockchains will be harder to get under control by an adversary than a single huge-ass blockchain with Gigabyte blocks (intentional hyperbole, but you should get the point). However it still doesn't change the fact that on-chain scaling as we know it is a linear function, no matter how we spread transactions across different currencies. It doesn't help that atomic cross-chain swaps still need to be settled at one point, thus hitting their respective blockchains and requiring those to have blockspace available in the first place.

Either way, I'm looking forward to see what atomic cross-chain swaps will bring -- seamless integration of cryptocurrencies and utility tokens come to mind -- I just don't think improved scalability in terms of transaction throughput will be one of its main use cases.

[RGBKey]

layers
layers
layers

You can describe different cryptocurrencies with different Blockchains as "layers of the Bitcoin blockchain" as many times as you like (gee, I wonder whether you'll try to repeat this falsehood again in future? :/ ), it will never be true.

In order to be a layer of Bitcoin, a protocol must use valid script of the Bitcoin protocol, and valid/spendable inputs/outputs from the Bitcoin blockchain. Please do not attempt to mislead people with your "biggest-blocks by any means necessary" rhetorical tricks, you've been told enough times already.

There would be no point to your scheme anyway, blockchains scale tx throughput badly, adding blockchains therefore cannot improve scalability better than real additional protocol layers (which are not constrained by the same resource costs as the blockchain base layer).

In what way is it my "scheme"?  It's merely a potential future that could unfold.  We all know that none of this is set in stone and the picture in future could look entirely different from what any of us currently imagine.  I just think that if hopping from one blockchain to another becomes a seamless and simple process, the lines may well start to become blurred.  People may stop seeing altcoins as separate entities and it may all just become different denominations of the same money.  By all means continue being the maximalist zealot of the "one true blockchain", but there's little you can do if others see it differently.  You wanted Lightning, this is one of the doors it might open.  Then again, it might not.

While I'm also excited about the potential applications that atomic cross-chain swaps could enable, I have to agree with Carlton Banks that further improving on-chain scalability by utilizing atomic cross-chain swaps to spread transactions across multiple blockchains -- effectively using it as a load-balancing method of sorts -- is unlikely to come to fruition. I do like your vision of blurred lines between various cryptocurrencies though.

Of course transactions spread across multiple blockchains will be harder to get under control by an adversary than a single huge-ass blockchain with Gigabyte blocks (intentional hyperbole, but you should get the point). However it still doesn't change the fact that on-chain scaling as we know it is a linear function, no matter how we spread transactions across different currencies. It doesn't help that atomic cross-chain swaps still need to be settled at one point, thus hitting their respective blockchains and requiring those to have blockspace available in the first place.

Either way, I'm looking forward to see what atomic cross-chain swaps will bring -- seamless integration of cryptocurrencies and utility tokens come to mind -- I just don't think improved scalability in terms of transaction throughput will be one of its main use cases.

I would guess that we would see atomic swaps become available, but that not many people would use them honestly.

[Carlton Banks]

Of course transactions spread across multiple blockchains will be harder to get under control by an adversary than a single huge-ass blockchain with Gigabyte blocks (intentional hyperbole, but you should get the point).

This resembles the whole extension-blocks model, and I believe it's flawed (I'm not the only one). The flaws are too serious, but that hasn't stopped strangely persistent promoters of this idea from pushing the concept (Drivechain devs for instance).

However it still doesn't change the fact that on-chain scaling as we know it is a linear function, no matter how we spread transactions across different currencies. It doesn't help that atomic cross-chain swaps still need to be settled at one point, thus hitting their respective blockchains and requiring those to have blockspace available in the first place.

Exactly. There's little difference (in scaling terms) between blockchain + auxilliary blockchain and blockchain + limit increase. Worse, the monetary and security differences only make the situation more dire: pegged units in a different chain essentially inflates Bitcoin's money supply, and the network rules are subject to the whims of whoever owns majority hashing power on the auxilliary chain.

Monopolist miner manufacturers will love the sidechain "scaling solution" approach, they can create secret or proprietary hashing tech, use clever marketing (and every other underhand tactic) to convince people to swap onto their chain, then they have their own private Bitcoin adjunct to play all sorts of further games with. Hmmm, why does that description sound so familiar....

Either way, I'm looking forward to see what atomic cross-chain swaps will bring -- seamless integration of cryptocurrencies and utility tokens come to mind -- I just don't think improved scalability in terms of transaction throughput will be one of its main use cases.

I think cross-chain atomic swaps make alot of sense for swapping digital assets in a peer-to-peer way, that's revolutionary. There aren't many to choose from to make that happen just yet (.bit website domains, perhaps?), but that will come in time. Swapping other cryptocurrencies makes sense in the short term, but the market is likely to favour a single dominant currency in the long term (unless there is a fundamental reason why one cryptocurrency cannot fulfill all possible use-cases in the long term).

As a scaling tech, it's simultaneously risible and deceitful.

[DooMAD]

DooMAD, I've proven you use deceitful arguments to promote bad ideas before. Where's your proof for any of your claims?

The fact that you're now reduced to using obvious lies ("sidechains are Bitcoin layers", lol) only demonstrates how desperate your position has become.

All you've proven is that every single time someone expresses an idea of the future you disagree with, you label it dishonest.  My "position" is that mass adoption means it has to work for everyone.  I don't think I can make that any more clear than I have on previous occasions.  Now, instead of telling us what won't work, how about you try telling us what will?  Maybe stop shitting up the thread with your Bonapartism and tell us how you see scalability unfolding if your vision is so much more "honest" than mine.  I won't be calling you dishonest if your speculations now aren't what happens when the time comes, so let's hear it.  How do you think mass adoption will play out in terms of functionality?  Which metrics do you believe we'll employ to measure usage if TPS isn't viable?  Or are you just waiting for someone in authority to tell you how it's going to be?  

While I'm also excited about the potential applications that atomic cross-chain swaps could enable, I have to agree with Carlton Banks that further improving on-chain scalability by utilizing atomic cross-chain swaps to spread transactions across multiple blockchains -- effectively using it as a load-balancing method of sorts -- is unlikely to come to fruition. I do like your vision of blurred lines between various cryptocurrencies though.

Of course transactions spread across multiple blockchains will be harder to get under control by an adversary than a single huge-ass blockchain with Gigabyte blocks (intentional hyperbole, but you should get the point). However it still doesn't change the fact that on-chain scaling as we know it is a linear function, no matter how we spread transactions across different currencies. It doesn't help that atomic cross-chain swaps still need to be settled at one point, thus hitting their respective blockchains and requiring those to have blockspace available in the first place.

True enough.  Atomic swaps are also currently limited to coins of the same hash algorithm, so it remains to be seen which ones will actually be available to swap with.  It mostly just seemed like a nice excuse to put aside some of the old divisions and see some unity for a change.  Perhaps it is too bold an idea to be practical (or even socially acceptable if some lunatics are to be believed).  

I'm curious to see, once LN usage becomes a regular, everyday thing for the majority of participants, what metrics we'll actually be using to gauge the overall success.  I suppose available blockspace on layer 0 will perhaps be the most telling, since we simply won't know precisely how many off-chain transactions are being made.  It would be nice not have to rely on publicised stat reporting from the merchants, but you're probably right in that it may be the only option.  If that's the case, we almost certainly won't be using TPS as one of the primary measurements, given that it will be more of a general estimate based on what limited data is available.

[Anti-Cen]

But lightning is not decentralized and it's not on-block so really it's needs to be measured against TPS of someone like
Coinbase where digits move from pool accounts and not against real cryoto-coins.

If block-chain was so good then why accept anything less

[Kprawn]

My intention with this question was not to draw the shills and trolls out of their caves, but they come crawling out as soon as

they sniff an opportunity to spread their FUD and misinformation. If we draw a scaling graph now and we compare BCash and

some of the other Alt coins, then Bitcoin {BTC} with the LN will kick their ass. So they should rather crawl back into

their little FUD caves. Lightning Network.... to infinity and beyond!  

[HeRetiK]

However it still doesn't change the fact that on-chain scaling as we know it is a linear function, no matter how we spread transactions across different currencies. It doesn't help that atomic cross-chain swaps still need to be settled at one point, thus hitting their respective blockchains and requiring those to have blockspace available in the first place.

Exactly. There's little difference (in scaling terms) between blockchain + auxilliary blockchain and blockchain + limit increase. Worse, the monetary and security differences only make the situation more dire: pegged units in a different chain essentially inflates Bitcoin's money supply, and the network rules are subject to the whims of whoever owns majority hashing power on the auxilliary chain.

Monopolist miner manufacturers will love the sidechain "scaling solution" approach, they can create secret or proprietary hashing tech, use clever marketing (and every other underhand tactic) to convince people to swap onto their chain, then they have their own private Bitcoin adjunct to play all sorts of further games with. Hmmm, why does that description sound so familiar....

Interesting point on how hashing power differences between Bitcoin and auxilliary chains / swappable alt coins could enable new attack vectors for market manipulation. I personally doubt that pegged units will act as an inflation of Bitcoin's money supply as neither do alts nor forkcoins (at least in my book, others may see this differently) but it will definitely change the way the game is played -- for better or worse. Good food for thought, I'll have to let your post sink in a bit.

[...] Swapping other cryptocurrencies makes sense in the short term, but the market is likely to favour a single dominant currency in the long term (unless there is a fundamental reason why one cryptocurrency cannot fulfill all possible use-cases in the long term).

I also expect the market to consolidate into a handful of currencies in the long term. While I expect the best-scaling currency to come out on top -- hopefully a decentralized one, as everything else is practically cheating imho -- I'm not convinced that a single cryptocurrency will be able to handle all desirable use cases. If only because there are rarely catch-all solutions that actually perform well.

I'm curious to see, once LN usage becomes a regular, everyday thing for the majority of participants, what metrics we'll actually be using to gauge the overall success.  I suppose available blockspace on layer 0 will perhaps be the most telling, since we simply won't know precisely how many off-chain transactions are being made.  It would be nice not have to rely on publicised stat reporting from the merchants, but you're probably right in that it may be the only option.  If that's the case, we almost certainly won't be using TPS as one of the primary measurements, given that it will be more of a general estimate based on what limited data is available.

I think if LN usage becomes a regular, everyday thing we use, then that alone will already be a sign of success. Sounds tautological, but what I'm trying to say is: If LN is a viable scaling solution, people will use it. Sure, it might take a while until it becomes more widespread, but if LN manages to cover people's needs in terms of security, reliability and usability, it will become the way to go. Most of which I deem a question of the right implementation. If people don't use LN, for whatever reason, it will have failed as a scaling solution, regardless of technological soundness and effectiveness.

[ZmnSCPxj]

As what is really wanted, for the purpose of advertising/press spin, is the maximum capacity, then one may make the below synthetic metric:

• Get an ordinary consumer-grade LN node hardware. Stress-test a typical LN implementation and see how many payment forwards per second it can handle on that hardware.
• Measure typical payment success rate, ie. for c-lightning, 1 / sendpay_tries returned by pay command.
• Measure number of nodes on the network.
• Measure typical successful route length.
• Multiply forwards per second by payment success rate by number of nodes and divide by route length to get maximum theoretical transaction rate

[Carlton Banks]

Interesting point on how hashing power differences between Bitcoin and auxilliary chains / swappable alt coins could enable new attack vectors for market manipulation. I personally doubt that pegged units will act as an inflation of Bitcoin's money supply as neither do alts nor forkcoins (at least in my book, others may see this differently)

Well, pegging the rate between BTC and a sidechain 1:1 could certainly be exploited to influence perception of supply inflation, but only changes to Bitcoin's own input validation rules could introduce inflation directly to the Bitcoin blockchain. The markets would sort out the mess of course (1:1 cannot be enforced in a free market), but the mess could be avoided if the notion isn't popularised.

As I said, I think atomic swaps between Bitcoin and other digital assets (like contracts or domain names) will be truly innovative, but the useful assets don't quite exist yet (I'd be interested to know if there's a popular digital asset that I'm unaware of). The key point being that such assets would be access, ownership, identity or some other data, not abstract value (i.e. money tokens).

I also expect the market to consolidate into a handful of currencies in the long term. While I expect the best-scaling currency to come out on top -- hopefully a decentralized one, as everything else is practically cheating imho -- I'm not convinced that a single cryptocurrency will be able to handle all desirable use cases. If only because there are rarely catch-all solutions that actually perform well.

The only monetary use case Bitcoin is not capable of is that of the privacy-centric coins, but privacy enhancements will end up being added to Bitcoin in one form or another (aggregated signatures & Mimblewimble are possible future such privacy enhancements). Maybe there'll always be a better privacy coin for enthusiasts, but I suspect Bitcoin will eventually do privacy more than well enough.

In the case of money, some compromise (i.e. a catch all) is always better IMO; history has already demonstrated that only a minority of people will contemplate why good money has a set of definitive characteristics. The majority have always been disinterested in the qualitative difference between this type of money and that type, they just want to adhere to a norm and let those that are really interested discern what that norm is. We're part of a self-selected discerning group, but mainstream use of cryptocurrencies inherently involves those that don't want to make monetary decisions, they'll just want to stick to whatever coin is most widely accepted to simplify commerce for them.
 

if LN manages to cover people's needs in terms of security, reliability and usability, it will become the way to go. Most of which I deem a question of the right implementation. If people don't use LN, for whatever reason, it will have failed as a scaling solution, regardless of technological soundness and effectiveness.

The biggest challenge for Lightning to me is security. I'm probably exposing some ignorance here, but it seems to me that having unencrypted private keys in the memory of permanently online machines is risky. Maybe there's a way of mitigating that, or perhaps that mitigation exists already.

[RGBKey]

if LN manages to cover people's needs in terms of security, reliability and usability, it will become the way to go. Most of which I deem a question of the right implementation. If people don't use LN, for whatever reason, it will have failed as a scaling solution, regardless of technological soundness and effectiveness.

The biggest challenge for Lightning to me is security. I'm probably exposing some ignorance here, but it seems to me that having unencrypted private keys in the memory of permanently online machines is risky. Maybe there's a way of mitigating that, or perhaps that mitigation exists already.

I feel the same way, but think about SSL too. I'm thinking that if we're able to make web servers that have access to an unencrypted key and we can secure those that we should be able to do the same with lightning nodes. Maybe I'm also being quite naieve, but I'm hoping it won't be too big of a problem.