```
bitcoind -par=1
```

Excerpt from the `debug.log`:

```
Using 0 threads for script verification
```

Zero? I guess not ;)
{
        WAIT_LOCK(g_genesis_wait_mutex, lock);
        
        
        
        while (!fHaveGenesis && !ShutdownRequested()) {
            g_genesis_wait_cv.wait_for(lock, std::chrono::milliseconds(500));
        }
        block_notify_genesis_wait_connection.disconnect();
    }
    if (ShutdownRequested()) {
        return false;
    }
    
    int chain_active_height;
    
    {
        LOCK(cs_main);
        LogPrintf("block tree size = %u\n", ::BlockIndex().size());
        chain_active_height = ::ChainActive().Height();
    }
    LogPrintf("nBestHeight = %d\n", chain_active_height);
    if (gArgs.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION))
        StartTorControl();
    Discover();
    
    if (gArgs.GetBoolArg("-upnp", DEFAULT_UPNP)) {
        StartMapPort();
    }
    CConnman::Options connOptions;