NXT :: descendant of Bitcoin - Updated Information

[Jean-Luc]

Alias assignment being undone? I didn´t touch the client when this message came.

It is not because of something you did. The block that had to be popped off contained an alias assignment transaction. When a block is popped off, an attempt is made to undo all transactions in it. But this type of transaction cannot be undone, and in this case a full rescan of the blockchain is needed.

[Jean-Luc]

du says: 257480 for current nxt_db folder

What? Mine is 111M only.

[ChuckOne]

Alias assignment being undone? I didn´t touch the client when this message came.

It is not because of something you did. The block that had to be popped off contained an alias assignment transaction. When a block is popped off, an attempt is made to undo all transactions in it. But this type of transaction cannot be undone, and in this case a full rescan of the blockchain is needed.

Interesting. Why can't this be undone?

[Jean-Luc]

Does this mean that we are actually generating checkpoint files on all the nodes all the time? If so, how much work would it be to have newly installed nodes query for the most recent db files and start with that, instead of redownloading the entire blockchain. Of course, must be peer verified checksums, etc.

I don't understand what you mean by checkpoint file. The rest is a bad idea.

[ChuckOne]

du says: 257480 for current nxt_db folder

What? Mine is 111M only.

Err:

Code:

pi@raspberrypi ~/nxt $ du -h nxt_db/
252M	nxt_db/

Wrong usage of du?

[Jean-Luc]

Interesting. Why can't this be undone?

Because to find out the previous value of the alias URL, if any, you need to go back through all previous transactions. In effect, again scanning the blockchain.

[mikesbmw]

Running 0.7.5:

I get a non-stop list of this:

height 66516 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:24.534] DEBUG: Failed to accept block 11979910396361888590 at
height 66516 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:26.139] DEBUG: Failed to accept block 11979910396361888590 at
height 66516 received from node3.mynxtcoin.org, blacklisting
[2014-02-14 22:01:27.190] DEBUG: Failed to accept block 11979910396361888590 at
height 66516 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:28.239] DEBUG: Failed to accept block 11979910396361888590 at
height 66516 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:40.314] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from node3.mynxtcoin.org, blacklisting
[2014-02-14 22:01:41.923] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from node3.mynxtcoin.org, blacklisting
[2014-02-14 22:01:42.979] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:44.029] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:45.634] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from node3.mynxtcoin.org, blacklisting
[2014-02-14 22:01:46.697] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:47.748] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:48.810] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:50.821] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from node3.mynxtcoin.org, blacklisting
[2014-02-14 22:01:51.923] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from vps2.nxtcrypto.org, blacklisting
[2014-02-14 22:01:53.745] DEBUG: Failed to accept block 12715248329747037589 at
height 66517 received from node90.nxtbase.com, blacklisting


EDIT: okay, seems to have stopped now after several hundred lines of this.

[ChuckOne]

Interesting. Why can't this be undone?

Because to find out the previous value of the alias URL, if any, you need to go back through all previous transactions. In effect, again scanning the blockchain.

Why not caching it?

[greyw00lf]

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

copying the db from the old version is definitely faster, because my Raspberry takes a long time to download the whole blockchain (maybe 1h? haven't really watched at the time precisely).

Scanning the blockchain now takes about 9 minutes on my Raspberry.
No issues at the moment with my Pi even unlocking my account via the GUI is fast now! Thanks Jean-Luc!

[ChuckOne]

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

copying the db from the old version is definitely faster, because my Raspberry takes a long time to download the whole blockchain (maybe 1h? haven't really watched at the time precisely).

Scanning the blockchain now takes about 9 minutes on my Raspberry.
No issues at the moment with my Pi even unlocking my account via the GUI is fast now! Thanks Jean-Luc!

Have you overclocked your Raspi?

[Come-from-Beyond]

Complexity of signing is O(1).

That is plain wrong. The more bits you have to sign the longer signing takes. The question is: how long in terms of the input length.

We would have O(n) if Sign(32_bytes) == Sign(64_bytes) / 2. Actually we have Sign(32_bytes) == Sign(3200_bytes) / 2, so it's more like O(1). Right?

[ChuckOne]

Does this mean that we are actually generating checkpoint files on all the nodes all the time? If so, how much work would it be to have newly installed nodes query for the most recent db files and start with that, instead of redownloading the entire blockchain. Of course, must be peer verified checksums, etc.

I don't understand what you mean by checkpoint file. The rest is a bad idea.

I think he means that nxt.h2.db could be considered a snapshot file.

[mcjavar]

Alias assignment being undone? I didn´t touch the client when this message came.

It is not because of something you did. The block that had to be popped off contained an alias assignment transaction. When a block is popped off, an attempt is made to undo all transactions in it. But this type of transaction cannot be undone, and in this case a full rescan of the blockchain is needed.

Thank you for clarification. How can a block "popp off"?

[greyw00lf]

du says: 257480 for current nxt_db folder

What? Mine is 111M only.

Err:

Code:

pi@raspberrypi ~/nxt $ du -h nxt_db/
252M	nxt_db/

Wrong usage of du?

I have:

Code:

pi@rpi ~/nxt $ du -h nxt_db/
246M	nxt_db/

But i always copied the folder from one version to the next... maybe that's why?

[greyw00lf]

Have you overclocked your Raspi?

No, i don't know if i will do that, i don't have anything to cool it (no heat sink...) and my pi is in an ordinary plastic-case.

[jl777]

Does this mean that we are actually generating checkpoint files on all the nodes all the time? If so, how much work would it be to have newly installed nodes query for the most recent db files and start with that, instead of redownloading the entire blockchain. Of course, must be peer verified checksums, etc.

I don't understand what you mean by checkpoint file. The rest is a bad idea.

It might be a bad idea, but the problem of how will small machines be able to keep up with 1000TPS volumes is unsolved.
checkpoint file would be "entire state of NXT blockchain" at specific intervals. I am assuming you are not storing the entire blockchain now that we have DB,but maybe that is incorrect?

Almost all NXT functions only need the most recent 1440 blocks, so if each machine kept those 1440 blocks locally, they can purge them after that. blockchain FIFO.

As the blockchain grows, it will take longer and longer for initial install. By having the entire state of NXT every hour, or even every day, in a decentralized peer validated form, would allow starting from the most recent hour (or day) and then start processing blocks from that point.

These two are totally independent technically, but combine to allow small raspis to continue forging and being full nodes
If checkpoint files are a bad idea, I can live with that. Is blockchain FIFO a bad idea too?

[Jean-Luc]

Code:

pi@raspberrypi ~/nxt $ du -h nxt_db/
252M	nxt_db/

Wrong usage of du?

No. I guess the database needs vacuuming once in a while. I will do that at shutdown, it means stopping the server will take slightly longer.

[greyw00lf]

Thanks! I am reluctant about the overclocking, but I run it with -856xmx ...

What does -856xmx do?

It is the memory available to the jvm, I quoted it wrong:

ps -ax
 2040 ?        SNl   61:45 /usr/bin/java -Xms128m -Xmx856m -jar start.jar STOP.PORT=7873 STOP.KEY=0815


-Xms128m is the minimum that is reserved at the start, and -Xmx856m is the maximum it can have, in megabytes. I often had crashes with a maximum smaller 450MB, but with giving it almost all the memory, it runs quite good.

Except that dl'ing the whole blockcahin is quite some venture.

i use -Xms320m -Xmx480m
how can you give it 856m? Don't you have a pi with 512MB? Or are you using swap? Or an other device?

[Jean-Luc]

Thank you for clarification. How can a block "popp off"?

With a little help from a stronger block that kicks him out

Only one block can be at the end of the chain, but multiple nodes try to generate blocks at the same time. The better one wins, if the other was attached first it gets popped off.

[Jean-Luc]

I am assuming you are not storing the entire blockchain now that we have DB,but maybe that is incorrect?

Almost all NXT functions only need the most recent 1440 blocks, so if each machine kept those 1440 blocks locally, they can purge them after that. blockchain FIFO.

If checkpoint files are a bad idea, I can live with that. Is blockchain FIFO a bad idea too?

Of course I store the whole blockchain, this is what the db contains.

You seem to be talking about blockchain trimming or pruning. This is in the plans, but not that soon.

Downloading the whole db will take longer than just the blockchain.