Ethereum Mining – How to Decrease Difficulty on a Private Testnet

difficultyminingtestnets

I've created a private test network. On the genesis.json file, I've changed the difficulty to 1. Yet, mining a block still takes hours on my CPU. I suspect that is due to some configuration related to the network adaptation.

What is the correct procedure to decrease the difficulty on a private testnet, so that I can mine the first blocks in a not very powerful CPU?

Best Answer

There are 2 ways to do this:

  • Change the value of difficulty parameter in genesis.json file to a small number(preferably set it to 0). You can refer to this example genesis file

    {
   "config": {
      "chainId": 1994,
      "homesteadBlock": 0,
      "eip155Block": 0,
      "eip158Block": 0,
      "byzantiumBlock": 0
   },
   "difficulty": "0x0", //difficulty set to zero in hexadecimal format
   "gasLimit": "0x8000000",
   "alloc": {
      "9a963d0eefeb62678d8efb48561c81e51c552797": { 
          "balance": "9606938044258990275541962092341162602522202993782792835301376" 
      },
      "30f28686aef33adbfbc13797b1d9f5a2f2759f56": { 
          "balance": "9606938044258990275541962092341162602522202993782792835301376" 
      }
   }
}

Problem with this method is that when the block number increases, the difficulty also starts increasing at a high rate. So, to tackle that problem refer to the below part.

  • You can reduce the rate of block difficulty increament by making some changes in the consensus code of go-ethereum. Open consensus.go which resides at consensus/ethash/consensus.go and search for the below line.

return CalcDifficulty(chain.Config(), time, parent)

Now replace the above line with the below one.

return big.NewInt(1).

Now build the go-ethereum using make geth command.

I strongly recommend you to go through this article for much detailed implementation of the above process.

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