NXT :: descendant of Bitcoin - Updated Information

[Pouncer]

Cfb, what do you mean by bad connections?

Maybe it's an incorrect word. Let me explain.

Imagine that u connected to a peer with almost no free memory. If u send him a transaction he may see it and even attempt to send back (and to other peers), but due to "not enough memory" error he won't be able to do this. Java virtual machine reserves not so much memory to Nxt by default and most of nodes face the memory error after a few hours of working. If u connected mostly to such peers then u get what I called "bad connections".

BTW, it's better to launch Nxt by adding -Xms and -Xmx options:

Code:

java -Xms512m -Xmx1024m -cp Nxt.zip Nxt

So if I am connected to 10 peers and my send tx was first received by peer # 5 and that peer has a low memory problem, then that tx will fail because it does not get propagated to other nodes. I'll have to wait until tx expires and try again, and hope the next peer (green status) does not have this problem. In the long run, this would certainly be a problem in usability. In my case, if I did not have a VPS, I would not be able to send any transaction since launch.

Does the blacklist feature take into account nodes that have this memory problem, ie nodes that cannot process tx data? Based on my observations and understanding of your explanation, it appears that the answer is "no". Can this be fixed?

[Sharky444]

Is there any Build newer than .15?

[Come-from-Beyond]

So if I am connected to 10 peers and my send tx was first received by peer # 5 and that peer has a low memory problem, then that tx will fail because it does not get propagated to other nodes. I'll have to wait until tx expires and try again, and hope the next peer (green status) does not have this problem. In the long run, this would certainly be a problem in usability. In my case, if I did not have a VPS, I would not be able to send any transaction since launch.

Does the blacklist feature take into account nodes that have this memory problem, ie nodes that cannot process tx data? Based on my observations and understanding of your explanation, it appears that the answer is "no". Can this be fixed?

Ur node sends a transaction to all peers. Before sending a transaction u can do a little test, just send 1 NXT back to urself. BCNext is working on resolving this issue. Most of nodes have 256 Mb reserved for JVM which is not enough.

Blacklist is for nodes that announced incorrect address or were unreachable. Remove nodes with sane address from the blacklist time to time.

[Come-from-Beyond]

Is there any Build newer than .15?

.17 - https://dl.dropboxusercontent.com/u/67242472/Nxt.zip

3 API requests were added and a little changes in the interface (transaction id is visible now).

[bitme]

I have problem with one of my sell transaction. Buyer admits receiving coins and then after some time next were gone from his account.
Was those coins stolen?

side question

how can the 100k you send me just go poof

25.11.2013 21:52:20      2119227607764707387      99'900            100      10+
25.11.2013 21:14:54      818877006463198736      100'000                         1      10+

with me doing nothing or sending nothing to noone?

Here is transaction
 http://88.198.210.245:7876/?request=getTransaction&transaction=18063112106693460272
Can it be treated as proof that i sent coins to buyer from account 818877006463198736 and he received it to address 3791936988034107349?

[Come-from-Beyond]

Here is transaction
 http://88.198.210.245:7876/?request=getTransaction&transaction=18063112106693460272
Can it be treated as proof that i sent coins to buyer from account 818877006463198736 and he received it to address 3791936988034107349?

Yes. This transaction does prove that.

[Come-from-Beyond]

Was those coins stolen?

Perhaps. In Russian subforum I saw a message that someone already picked a short secret phrase with 1 NXT on the balance.

[bitme]

Here is transaction
 http://88.198.210.245:7876/?request=getTransaction&transaction=18063112106693460272
Can it be treated as proof that i sent coins to buyer from account 818877006463198736 and he received it to address 3791936988034107349?

Yes. This transaction does prove that.

BTW account number 2119227607764707387 still holds 99900
 http://88.198.210.245:7876/?request=getBalance&account=2119227607764707387

[bitme]

I'll assume Bossland is honest then and used just weak secret phrase.
Let it be warning for all NEXT users, Use extremly strong phrases

[Come-from-Beyond]

After intensive profiling of Nxt client I seem to figured out why it crashes so often.



Nxt uses direct memory buffers for networking part. If Nxt requests such a buffer JVM takes space reserved for heap and gives it to the buffer. After the buffer is no longer needed JVM "forgets" its reference but reserved memory is not claimed immediately, it depends on OS internal mechanisms. After a while this chunk of RAM can be used again, but if the flow of requests is very intensive, then JVM simply runs out of free memory. That's why we can see a lot of "Not enough memory/heap" errors and NullPointerExceptions.

Could Java gurus confirm this, please?

[Sharky444]

Is there any Build newer than .15?

.17 - https://dl.dropboxusercontent.com/u/67242472/Nxt.zip

3 API requests were added and a little changes in the interface (transaction id is visible now).

Win7 x64, JRE 7.

Deleted all *.nxt files, run the client. Launched with java -Xms512m -Xmx1024m -cp Nxt.zip Nxt

It did catch up to the latest block. But few minutes later it's at 0 blocks again and this error is given:

[2013-11-29 22:41:28.814] Saving blocks...
[2013-11-29 22:41:29.001] ...Done
Exception in thread "pool-2-thread-4" java.nio.channels.WritePendingException
        at sun.nio.ch.AsynchronousSocketChannelImpl.write(Unknown Source)
        at sun.nio.ch.AsynchronousSocketChannelImpl.write(Unknown Source)
        at java.nio.channels.AsynchronousSocketChannel.write(Unknown Source)
        at Nxt$4.completed(Unknown Source)
        at Nxt$4.completed(Unknown Source)
        at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
        at sun.nio.ch.Invoker$2.run(Unknown Source)
        at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)

[Sharky444]

, it depends on OS internal mechanisms. After a while this chunk of RAM can be used again, but if the flow of requests is very intensive, then JVM simply runs out of free memory. That's why we can see a lot of "Not enough memory/heap" errors and NullPointerExceptions.

Could Java gurus confirm this, please?

It's not related to the OS, it's just Javas crappy memory handler.

edit:

With Build 17 Chrome has 80% CPU usage on Core i3 when the client is open on localhost.

[gradis]

java -Xms512m -Xmx1024m -cp Nxt.zip Nxt


Tried that then it reset back to 0

then tried the normal java -cp Nxt.zip Nxt but it cancelled saying block was broken. Had the NXT block\accounts etc zip u posted though and built from there using the normal java start up command.
 

[Come-from-Beyond]

java -Xms512m -Xmx1024m -cp Nxt.zip Nxt


Tried that then it reset back to 0

then tried the normal java -cp Nxt.zip Nxt but it cancelled saying block was broken. Had the NXT block\accounts etc zip u posted though and built from there using the normal java start up command.
 

These things r not related. It's still better to run with Xms/Xmx options.

[lyynx]

Woah, seems like we have some issues going on here now. My client is showing a balance of 0.00 in the top right header, transaction count jumped around on loading localhost. Blocks section is showing -4399 blocks and 4459 orphaned blocks

[Come-from-Beyond]

Woah, seems like we have some issues going on here now. My client is showing a balance of 0.00 in the top right header, transaction count jumped around on loading localhost. Blocks section is showing -4399 blocks and 4459 orphaned blocks

Remove all *.nxt files and start the client again.

[candelone]

What is the difference between the windows Client and the online wallet http://88.198.210.245:7875/? Did I just need a Password to access the wallet? what is of different people use the same password (secret phrase)?

[Jean-Luc]

It's not related to the OS, it's just Javas crappy memory handler.

edit:

With Build 17 Chrome has 80% CPU usage on Core i3 when the client is open on localhost.

The high CPU load after running the browser for some time is a separate problem, but it has nothing to do with java, this is a javascript issue in the client (i.e. in the browser). I also have to restart firefox on my desktop because it gets slower and slower after a while, even though I run the Nxt java process on a separate machine. So don't blame java for this at least.

[lyynx]

Woah, seems like we have some issues going on here now. My client is showing a balance of 0.00 in the top right header, transaction count jumped around on loading localhost. Blocks section is showing -4399 blocks and 4459 orphaned blocks

Remove all *.nxt files and start the client again.

Thank you, that fixed it.

[Snard]

If I wanted to get involved in Nxt, realistically how many coins would I need to purchase to start mining?