why my double spend transaction is not getting confirmed ?

[btctousd81]

okie, i tried double spending transaction.

here is the 1st tx. https://blockchain.info/tx/eb1e180825ad7ea0efadd8ab3227242759425331188316ac5f822fca12b2627a

Code:

{
   "ver":1,
   "inputs":[
      {
         "sequence":4294967295,
         "witness":"",
         "prev_out":{
            "spent":true,
            "tx_index":293095803,
            "type":0,
            "addr":"1QCoHemDLMTaSJb7heXUHLsu6YPyu5iDEv",
            "value":1267107,
            "n":12,
            "script":"76a914fe861b6c4e70b608cdaf14c905d05a964e685a0d88ac"
         },
         "script":"473044022028da216bb177e631d05373c2ac3013b3f72de511971a1b42e371ea69ba03938902206eff871f4b02ca7520e13812a915b64acb1d0008e3f4c8d3f7f8c11283eaf238014104c41916365abb2b5d09192f5f2dbeafec208f020f12570a184dbadc3e5859599704f14351d0087efa49d245b328984989d5caf9450f34bfc0ed16e96b58fa9913"
      }
   ],
   "weight":884,
   "block_height":490609,
   "relayed_by":"0.0.0.0",
   "out":[
      {
         "spent":false,
         "tx_index":293095841,
         "type":0,
         "addr":"3QvxvxuotS5PuTjmVUpWN6sVkfzUfX3RFV",
         "value":1197843,
         "n":0,
         "script":"a914feee37e10d4ecc8539340e640dad5abb6ed998ad87"
      }
   ],
   "lock_time":0,
   "size":221,
   "double_spend":false,
   "time":1508413927,
   "tx_index":293095841,
   "vin_sz":1,
   "hash":"eb1e180825ad7ea0efadd8ab3227242759425331188316ac5f822fca12b2627a",
   "vout_sz":1
}

Code:

Inputs and Outputs
Total Input	$ 71.87
Total Output	$ 67.94
Fees	$ 3.93
Fee per byte	313.412 sat/B
Fee per weight unit	78.353 sat/WU
Estimated BTC Transacted	$ 67.94

and here is the 2nd tx aka. double spend. https://blockchain.info/tx/1ba66182c899424550b76a608b7acc8247e9e8bdbbb324eb36a5e6ae7176f56c

Code:

{
   "ver":1,
   "inputs":[
      {
         "sequence":4294967295,
         "witness":"",
         "prev_out":{
            "spent":true,
            "tx_index":293095803,
            "type":0,
            "addr":"1QCoHemDLMTaSJb7heXUHLsu6YPyu5iDEv",
            "value":1267107,
            "n":12,
            "script":"76a914fe861b6c4e70b608cdaf14c905d05a964e685a0d88ac"
         },
         "script":"483045022100aa8c501856299aea6654848d2ea63aa5cce8451003b4188e39c4a19df8f3f4ee02207c3fd2ef2ba4aba5643902ffa66b042100422133b000fb70bb74ad7e7ae524e8014104c41916365abb2b5d09192f5f2dbeafec208f020f12570a184dbadc3e5859599704f14351d0087efa49d245b328984989d5caf9450f34bfc0ed16e96b58fa9913"
      }
   ],
   "weight":896,
   "relayed_by":"127.0.0.1",
   "out":[
      {
         "spent":false,
         "tx_index":293095807,
         "type":0,
         "addr":"1yTS2FGX7UzVodGaaovDXP6pNhZDMimFe",
         "value":1043107,
         "n":0,
         "script":"76a914049326bcc8d30b333a5a3c612f453b18115a69d088ac"
      }
   ],
   "lock_time":0,
   "size":224,
   "double_spend":true,
   "time":1508413928,
   "tx_index":293095807,
   "vin_sz":1,
   "hash":"1ba66182c899424550b76a608b7acc8247e9e8bdbbb324eb36a5e6ae7176f56c",
   "vout_sz":1
}
 

Code:

Inputs and Outputs
Total Input	$ 71.87
Total Output	$ 59.16
Fees	$ 12.70
Fee per byte	1,000 sat/B
Fee per weight unit	250 sat/WU
Estimated BTC Transacted	$ 59.16

there is not much time delay while broadcasting the tx. its 1 second late, than the first one.
but still the first oine got confirmed ,
why is that ?

even my double spend tx's fees were higher that the 1st one.

[DannyHamilton]

The vast majority of nodes and miners will refuse to accept or relay a double spend transaction while the original is still in their mempool.  Therefore, most miners won't even receive the transaction and if they receive it they won't confirm it.

To accomplish what you are trying to do, you need to:

Get the transaction to miners that haven't seen the first transaction yet.
Get the transaction to miners that are willing to replace the earlier transaction in their mempool.
Hope that the miners that have accepted your double-spend transaction will complete a block with it before any other miners complete a block with the first transaction.


The more hashpower that is working on your second transaction, the better the odds that it will be confirmed, but as long as even 1 miner is working on the first transaction there is a chance that they will complete their block first.

[btctousd81]

The vast majority of nodes will refuse to accept or relay a double spend transaction while the original is still in their mempool.  Therefore, most miners won't even receive the transaction and if they receive it they won't confirm it.

even though , fees are way higher ?


 

[btctousd81]

The vast majority of nodes and miners will refuse to accept or relay a double spend transaction while the original is still in their mempool.  Therefore, most miners won't even receive the transaction and if they receive it they won't confirm it.

To accomplish what you are trying to do, you need to:

Get the transaction to miners that haven't seen the first transaction yet.
Get the transaction to miners that are willing to replace the earlier transaction in their mempool.
Hope that the miners that have accepted your double-spend transaction will complete a block with it before any other miners complete a block with the first transaction.


The more hashpower that is working on your second transaction, the better the odds that it will be confirmed, but as long as even 1 miner is working on the first transaction there is a chance that they will complete their block first.

okie., so timing and double spend accepting nodes plays major part.

[DannyHamilton]

The vast majority of nodes will refuse to accept or relay a double spend transaction while the original is still in their mempool.  Therefore, most miners won't even receive the transaction and if they receive it they won't confirm it.

even though , fees are way higher ?

Yes.

Unless the first transaction is built as a RBF transaction, nodes won't care how big the fee is.  They don't even look at the fee.  If the first transaction already exists in their mempool then the second transaction is an invalid transaction and is rejected.  It is not relayed to any peers, and the miners never even hear about it.

Many mining nodes are running default node behavior.  Therefore, if they already have the first transaction in their mempool, then their nodes will reject the transaction without even looking at the fee.