No tx fee so trying to double spend

[beltin]

Hello,

I was wondering if anyone can put my mind at ease and let me know if I messed up?

I sent a payment 0.998 using the Android client and it by default (which I didn't know) didn't place a fee on the transaction.

https://blockchain.info/tx/2a4e88ad42f79aa68ae06bec984d8952c29326ab1037de97d944bcfae5a7d460

As I needed to get this sent within an hour I read in some threads about double spending to overcome this. So I imported my private key to bitcoin-qt and I then tried to send all my coins 1.2ish to another address (to affectively double spend). I've included a fee this time which was 0.00025 per kB which then totalled 0.00075 due to the transaction size. I've left the transaction for about 30 minutes and its still not confirmed and only propagated to 21 nodes in about 30 minutes. At this rate is seems like it will take a long time although I've included a fee?

I know its not hit blockchain yet - https://blockchain.info/search/6e1794b68f17b8a375d1f9a97a2adf3e9fd6840856b4ddc23adb8a8ac77d5b2b

So my questions are: -

1) Will the double spend method work?

2) Would Blockchain give up after a while with the original transaction? Its 2413 bytes.

3) Why is blockchain-qt taking such a long time even though I've included a fee? Is this fee unreasonable?

4) Should I just remove the unconfirmed transaction using pywallet and wait on the original blockchain transaction?

 

Many thanks in advance - I have read around quite a few different thread before deciding to post as I'm now quite stumped!

[skilo]

I think it will go through eventually, I believe the client will continue to broadcast the transaction to the network until it gets processed.

Might take a few days though or maybe even a week.

[beltin]

I think it will go through eventually, I believe the client will continue to broadcast the transaction to the network until it gets processed.

Might take a few days though or maybe even a week.

Do you mean the tx without the fee?

Or the one from bitcoin-qt? But why would it take a few days to a week if I've put a fee on it?

Many thanks for your response.

[DannyHamilton]

Bitcoin is designed to make it very difficult to reverse a transaction once you send it.

If a peer receives a "double spend attempt" it will not relay it to any other peers.  It will simply drop it and keep the original transaction.  Therefore, since most peers have already heard about your first transaction, they are not willing to accept or relay your second one that tries to double-spend some of the inputs.  Since your peers are not willing to accept or relay the transaction, miners (and mining pools) are unaware of it.  This means it can't get confirmed.

The protocol is designed for peers to drop old unconfirmed transactions out of memory to make room for new transactions.  This can take anywhere from several hours to several days.

As long as your original wallet is not re-broadcasting the original transaction, and as long as nobody else (such as the recipient) is re-broadcasting the original transaction, you can wait a few days for the first transaction to be dropped from the memory pool of most peers.  Then you can broadcast the "double spend attempt".  Since most peers will no longer know about the original transaction any longer, the new transaction will likely be relayed and eventually confirmed.

[beltin]

Bitcoin is designed to make it very difficult to reverse a transaction once you send it.

If a peer receives a "double spend attempt" it will not relay it to any other peers.  It will simply drop it and keep the original transaction.  Therefore, since most peers have already heard about your first transaction, they are not willing to accept or relay your second one that tries to double-spend some of the inputs.  Since your peers are not willing to accept or relay the transaction, miners (and mining pools) are unaware of it.  This means it can't get confirmed.

The protocol is designed for peers to drop old unconfirmed transactions out of memory to make room for new transactions.  This can take anywhere from several hours to several days.

As long as your original wallet is not re-broadcasting the original transaction, and as long as nobody else (such as the recipient) is re-broadcasting the original transaction, you can wait a few days for the first transaction to be dropped from the memory pool of most peers.  Then you can broadcast the "double spend attempt".  Since most peers will no longer know about the original transaction any longer, the new transaction will likely be relayed and eventually confirmed.

Thanks for your reply.

Since my original transaction is on blockchain I believe it will keep automatically broadcasting? I guess I'll have to stop my double spend attempt and wait for my first transaction to eventually get through?

[DannyHamilton]

Bitcoin is designed to make it very difficult to reverse a transaction once you send it.

If a peer receives a "double spend attempt" it will not relay it to any other peers.  It will simply drop it and keep the original transaction.  Therefore, since most peers have already heard about your first transaction, they are not willing to accept or relay your second one that tries to double-spend some of the inputs.  Since your peers are not willing to accept or relay the transaction, miners (and mining pools) are unaware of it.  This means it can't get confirmed.

The protocol is designed for peers to drop old unconfirmed transactions out of memory to make room for new transactions.  This can take anywhere from several hours to several days.

As long as your original wallet is not re-broadcasting the original transaction, and as long as nobody else (such as the recipient) is re-broadcasting the original transaction, you can wait a few days for the first transaction to be dropped from the memory pool of most peers.  Then you can broadcast the "double spend attempt".  Since most peers will no longer know about the original transaction any longer, the new transaction will likely be relayed and eventually confirmed.

Thanks for your reply.

Since my original transaction is on blockchain I believe it will keep automatically broadcasting? I guess I'll have to stop my double spend attempt and wait for my first transaction to eventually get through?

I don't know if they've changed their policy but the last I heard they typically stop broadcasting the transaction if it hasn't been confirmed after somewhere around 3 to 5 days. They will then display the bitcoins in your wallet again so you can try to re-send them from your blockchain.info wallet (with a fee this time).

[beltin]

Okay I'll cancel the double spend attempt from my PC when I get home in 5 minutes.

[skilo]

I think it will go through eventually, I believe the client will continue to broadcast the transaction to the network until it gets processed.

Might take a few days though or maybe even a week.

Do you mean the tx without the fee?

Or the one from bitcoin-qt? But why would it take a few days to a week if I've put a fee on it?

Many thanks for your response.

Without the fee it will take longer but it will go through eventually.

[beltin]

I think it will go through eventually, I believe the client will continue to broadcast the transaction to the network until it gets processed.

Might take a few days though or maybe even a week.

Do you mean the tx without the fee?

Or the one from bitcoin-qt? But why would it take a few days to a week if I've put a fee on it?

Many thanks for your response.

Without the fee it will take longer but it will go through eventually.

Thanks. I was worried I first that they would disappear as such but that can't happen.

They'll either get there or come back to me.

[beltin]

My network propagation for my tx on Blockchain has now changed from 70 to 7??