init.cpp:1635 prints mapBlockIndex.size() without cs_main. This is technically a race (though it is rather inconsequential). At some point someone should fix this so tsan stops complaining.
{
    bool fClean = true;
    if (view.HaveCoin(out)) fClean = false; 
    if (undo.nHeight == 0) {
        
        
        
        const Coin& alternate = AccessByTxid(view, out.hash);
        if (!alternate.IsSpent()) {
            undo.nHeight = alternate.nHeight;
            undo.fCoinBase = alternate.fCoinBase;
        } else {
            return DISCONNECT_FAILED; 
        }
    }
    
    
    
    
    view.AddCoin(out, std::move(undo), !fClean);
    return fClean ? DISCONNECT_OK : DISCONNECT_UNCLEAN;
}
/** Undo the effects of this block (with given index) on the UTXO set represented by coins.
 *  When FAILED is returned, view is left in an indeterminate state. */
static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)