Implement command line argument to set the amount of agents created by the miner

Defaults to the amount of cores available on the CPU

eth/backend.go

@@ -53,6 +53,8 @@ type Config struct {
 	Shh  bool
 	Dial bool
 
+	MinerThreads int
+
 	KeyManager *crypto.KeyManager
 }
 
@@ -153,7 +155,7 @@ func New(config *Config) (*Ethereum, error) {
 	eth.blockProcessor = core.NewBlockProcessor(db, eth.txPool, eth.chainManager, eth.EventMux())
 	eth.chainManager.SetProcessor(eth.blockProcessor)
 	eth.whisper = whisper.New()
-	eth.miner = miner.New(keyManager.Address(), eth)
+	eth.miner = miner.New(keyManager.Address(), eth, config.MinerThreads)
 
 	hasBlock := eth.chainManager.HasBlock
 	insertChain := eth.chainManager.InsertChain