```
bitcoind -par=1
```

Excerpt from the `debug.log`:

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

Zero? I guess not ;)
if (node.peer_logic) UnregisterValidationInterface(node.peer_logic.get());
    if (node.connman) node.connman->Stop();
    if (g_txindex) g_txindex->Stop();
    ForEachBlockFilterIndex([](BlockFilterIndex& index) { index.Stop(); });
    StopTorControl();
    
    
    threadGroup.interrupt_all();
    threadGroup.join_all();
    
    
    node.peer_logic.reset();
    node.connman.reset();
    node.banman.reset();
    g_txindex.reset();
    DestroyAllBlockFilterIndexes();
    if (::mempool.IsLoaded() && gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
        DumpMempool(::mempool);
    }
    if (fFeeEstimatesInitialized)
    {
        ::feeEstimator.FlushUnconfirmed();
        fs::path est_path = GetDataDir() / FEE_ESTIMATES_FILENAME;
        CAutoFile est_fileout(fsbridge::fopen(est_path, "wb"), SER_DISK, CLIENT_VERSION);
        if (!est_fileout.IsNull())
            ::feeEstimator.Write(est_fileout);
        else
            LogPrintf("%s: Failed to write fee estimates to %s\n", __func__, est_path.string());