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.
#ifndef BITCOIN_VALIDATION_H
#define BITCOIN_VALIDATION_H
#if defined(HAVE_CONFIG_H)
#include "config/bitcoin-config.h"
#endif
#include "amount.h"
#include "coins.h"
#include "fs.h"
#include "protocol.h" 
#include "policy/feerate.h"
#include "script/script_error.h"
#include "sync.h"
#include "versionbits.h"
#include <algorithm>
#include <exception>
#include <map>
#include <set>
#include <stdint.h>
#include <string>
#include <utility>
#include <vector>
#include <atomic>
class CBlockIndex;