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Parallelize script verification

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* During block verification (when parallelism is requested), script
  check actions are stored instead of being executed immediately.
* After every processed transactions, its signature actions are
  pushed to a CScriptCheckQueue, which maintains a queue and some
  synchronization mechanism.
* Two or more threads (if enabled) start processing elements from
  this queue,
* When the block connection code is finished processing transactions,
  it joins the worker pool until the queue is empty.

As cs_main is held the entire time, and all verification must be
finished before the block continues processing, this does not reach
the best possible performance. It is a less drastic change than
some more advanced mechanisms (like doing verification out-of-band
entirely, and rolling back blocks when a failure is detected).

The -par=N flag controls the number of threads (1-16). 0 means auto,
and is the default.
This commit is contained in:
Pieter Wuille 2012-12-01 23:04:14 +01:00
parent 1d70f4bde8
commit f9cae832e6
7 changed files with 281 additions and 6 deletions
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1
bitcoin-qt.pro
View file

@ -156,6 +156,7 @@ HEADERS += src/qt/bitcoingui.h \
src/init.h \
src/irc.h \
src/mruset.h \
src/checkqueue.h \
src/json/json_spirit_writer_template.h \
src/json/json_spirit_writer.h \
src/json/json_spirit_value.h \

206
src/checkqueue.h Normal file
View file

@ -0,0 +1,206 @@
// Copyright (c) 2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef CHECKQUEUE_H
#define CHECKQUEUE_H
#include <boost/thread/mutex.hpp>
#include <boost/thread/locks.hpp>
#include <boost/thread/condition_variable.hpp>
#include <vector>
#include <algorithm>
template<typename T> class CCheckQueueControl;
/** Queue for verifications that have to be performed.
* The verifications are represented by a type T, which must provide an
* operator(), returning a bool.
*
* One thread (the master) is assumed to push batches of verifications
* onto the queue, where they are processed by N-1 worker threads. When
* the master is done adding work, it temporarily joins the worker pool
* as an N'th worker, until all jobs are done.
*/
template<typename T> class CCheckQueue {
private:
// Mutex to protect the inner state
boost::mutex mutex;
// Worker threads block on this when out of work
boost::condition_variable condWorker;
// Master thread blocks on this when out of work
boost::condition_variable condMaster;
// Quit method blocks on this until all workers are gone
boost::condition_variable condQuit;
// The queue of elements to be processed.
// As the order of booleans doesn't matter, it is used as a LIFO (stack)
std::vector<T> queue;
// The number of workers (including the master) that are idle.
int nIdle;
// The total number of workers (including the master).
int nTotal;
// The temporary evaluation result.
bool fAllOk;
// Number of verifications that haven't completed yet.
// This includes elements that are not anymore in queue, but still in
// worker's own batches.
unsigned int nTodo;
// Whether we're shutting down.
bool fQuit;
// The maximum number of elements to be processed in one batch
unsigned int nBatchSize;
// Internal function that does bulk of the verification work.
bool Loop(bool fMaster = false) {
boost::condition_variable &cond = fMaster ? condMaster : condWorker;
std::vector<T> vChecks;
vChecks.reserve(nBatchSize);
unsigned int nNow = 0;
bool fOk = true;
do {
{
boost::unique_lock<boost::mutex> lock(mutex);
// first do the clean-up of the previous loop run (allowing us to do it in the same critsect)
if (nNow) {
fAllOk &= fOk;
nTodo -= nNow;
if (nTodo == 0 && !fMaster)
// We processed the last element; inform the master he can exit and return the result
condMaster.notify_one();
} else {
// first iteration
nTotal++;
}
// logically, the do loop starts here
while (queue.empty()) {
if ((fMaster || fQuit) && nTodo == 0) {
nTotal--;
if (nTotal==0)
condQuit.notify_one();
bool fRet = fAllOk;
// reset the status for new work later
if (fMaster)
fAllOk = true;
// return the current status
return fRet;
}
nIdle++;
cond.wait(lock); // wait
nIdle--;
}
// Decide how many work units to process now.
// * Do not try to do everything at once, but aim for increasingly smaller batches so
// all workers finish approximately simultaneously.
// * Try to account for idle jobs which will instantly start helping.
// * Don't do batches smaller than 1 (duh), or larger than nBatchSize.
nNow = std::max(1U, std::min(nBatchSize, (unsigned int)queue.size() / (nTotal + nIdle + 1)));
vChecks.resize(nNow);
for (unsigned int i = 0; i < nNow; i++) {
// We want the lock on the mutex to be as short as possible, so swap jobs from the global
// queue to the local batch vector instead of copying.
vChecks[i].swap(queue.back());
queue.pop_back();
}
// Check whether we need to do work at all
fOk = fAllOk;
}
// execute work
BOOST_FOREACH(T &check, vChecks)
if (fOk)
fOk = check();
vChecks.clear();
} while(true);
}
public:
// Create a new check queue
CCheckQueue(unsigned int nBatchSizeIn) :
nIdle(0), nTotal(0), fAllOk(true), nTodo(0), fQuit(false), nBatchSize(nBatchSizeIn) {}
// Worker thread
void Thread() {
Loop();
}
// Wait until execution finishes, and return whether all evaluations where succesful.
bool Wait() {
return Loop(true);
}
// Add a batch of checks to the queue
void Add(std::vector<T> &vChecks) {
boost::unique_lock<boost::mutex> lock(mutex);
BOOST_FOREACH(T &check, vChecks) {
queue.push_back(T());
check.swap(queue.back());
}
nTodo += vChecks.size();
if (vChecks.size() == 1)
condWorker.notify_one();
else if (vChecks.size() > 1)
condWorker.notify_all();
}
// Shut the queue down
void Quit() {
boost::unique_lock<boost::mutex> lock(mutex);
fQuit = true;
// No need to wake the master, as he will quit automatically when all jobs are
// done.
condWorker.notify_all();
while (nTotal > 0)
condQuit.wait(lock);
}
friend class CCheckQueueControl<T>;
};
/** RAII-style controller object for a CCheckQueue that guarantees the passed
* queue is finished before continuing.
*/
template<typename T> class CCheckQueueControl {
private:
CCheckQueue<T> *pqueue;
bool fDone;
public:
CCheckQueueControl(CCheckQueue<T> *pqueueIn) : pqueue(pqueueIn), fDone(false) {
// passed queue is supposed to be unused, or NULL
if (pqueue != NULL) {
assert(pqueue->nTotal == pqueue->nIdle);
assert(pqueue->nTodo == 0);
assert(pqueue->fAllOk == true);
}
}
bool Wait() {
if (pqueue == NULL)
return true;
bool fRet = pqueue->Wait();
fDone = true;
return fRet;
}
void Add(std::vector<T> &vChecks) {
if (pqueue != NULL)
pqueue->Add(vChecks);
}
~CCheckQueueControl() {
if (!fDone)
Wait();
}
};
#endif

20
src/init.cpp
View file

@ -84,6 +84,10 @@ void Shutdown(void* parg)
fShutdown = true;
nTransactionsUpdated++;
bitdb.Flush(false);
{
LOCK(cs_main);
ThreadScriptCheckQuit();
}
StopNode();
{
LOCK(cs_main);
@ -303,6 +307,7 @@ std::string HelpMessage()
" -checklevel=<n> " + _("How thorough the block verification is (0-6, default: 1)") + "\n" +
" -loadblock=<file> " + _("Imports blocks from external blk000??.dat file") + "\n" +
" -reindex " + _("Rebuild blockchain index from current blk000??.dat files") + "\n" +
" -par=N " + _("Set the number of script verification threads (1-16, 0=auto, default: 0)") + "\n" +
"\n" + _("Block creation options:") + "\n" +
" -blockminsize=<n> " + _("Set minimum block size in bytes (default: 0)") + "\n" +
@ -484,6 +489,15 @@ bool AppInit2()
fDebug = GetBoolArg("-debug");
fBenchmark = GetBoolArg("-benchmark");
// -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
nScriptCheckThreads = GetArg("-par", 0);
if (nScriptCheckThreads == 0)
nScriptCheckThreads = boost::thread::hardware_concurrency();
if (nScriptCheckThreads <= 1)
nScriptCheckThreads = 0;
else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS)
nScriptCheckThreads = MAX_SCRIPTCHECK_THREADS;
// -debug implies fDebug*
if (fDebug)
fDebugNet = true;
@ -579,6 +593,12 @@ bool AppInit2()
if (fDaemon)
fprintf(stdout, "Bitcoin server starting\n");
if (nScriptCheckThreads) {
printf("Using %u threads for script verification\n", nScriptCheckThreads);
for (int i=0; i<nScriptCheckThreads-1; i++)
NewThread(ThreadScriptCheck, NULL);
}
int64 nStart;
// ********************************************************* Step 5: verify database integrity

40
src/main.cpp
View file

@ -10,6 +10,7 @@
#include "net.h"
#include "init.h"
#include "ui_interface.h"
#include "checkqueue.h"
#include <boost/algorithm/string/replace.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
@ -40,6 +41,7 @@ uint256 hashBestChain = 0;
CBlockIndex* pindexBest = NULL;
set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexValid; // may contain all CBlockIndex*'s that have validness >=BLOCK_VALID_TRANSACTIONS, and must contain those who aren't failed
int64 nTimeBestReceived = 0;
int nScriptCheckThreads = 0;
bool fImporting = false;
bool fReindex = false;
bool fBenchmark = false;
@ -1360,10 +1362,13 @@ bool VerifySignature(const CCoins& txFrom, const CTransaction& txTo, unsigned in
return CScriptCheck(txFrom, txTo, nIn, flags, nHashType)();
}
bool CTransaction::CheckInputs(CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags) const
bool CTransaction::CheckInputs(CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, std::vector<CScriptCheck> *pvChecks) const
{
if (!IsCoinBase())
{
if (pvChecks)
pvChecks->reserve(vin.size());
// This doesn't trigger the DoS code on purpose; if it did, it would make it easier
// for an attacker to attempt to split the network.
if (!HaveInputs(inputs))
@ -1416,8 +1421,12 @@ bool CTransaction::CheckInputs(CCoinsViewCache &inputs, bool fScriptChecks, unsi
const CCoins &coins = inputs.GetCoins(prevout.hash);
// Verify signature
if (!VerifySignature(coins, *this, i, flags, 0))
return DoS(100,error("CheckInputs() : %s VerifySignature failed", GetHash().ToString().substr(0,10).c_str()));
CScriptCheck check(coins, *this, i, flags, 0);
if (pvChecks) {
pvChecks->push_back(CScriptCheck());
check.swap(pvChecks->back());
} else if (!check())
return DoS(100,false);
}
}
}
@ -1567,6 +1576,19 @@ void static FlushBlockFile()
bool FindUndoPos(int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
void ThreadScriptCheck(void*) {
vnThreadsRunning[THREAD_SCRIPTCHECK]++;
RenameThread("bitcoin-scriptch");
scriptcheckqueue.Thread();
vnThreadsRunning[THREAD_SCRIPTCHECK]--;
}
void ThreadScriptCheckQuit() {
scriptcheckqueue.Quit();
}
bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJustCheck)
{
// Check it again in case a previous version let a bad block in
@ -1607,6 +1629,8 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
CBlockUndo blockundo;
CCheckQueueControl<CScriptCheck> control(fScriptChecks && nScriptCheckThreads ? &scriptcheckqueue : NULL);
int64 nStart = GetTimeMicros();
int64 nFees = 0;
int nInputs = 0;
@ -1638,8 +1662,10 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
nFees += tx.GetValueIn(view)-tx.GetValueOut();
if (!tx.CheckInputs(view, fScriptChecks, fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE))
std::vector<CScriptCheck> vChecks;
if (!tx.CheckInputs(view, fScriptChecks, fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE, nScriptCheckThreads ? &vChecks : NULL))
return false;
control.Add(vChecks);
}
CTxUndo txundo;
@ -1656,6 +1682,12 @@ bool CBlock::ConnectBlock(CBlockIndex* pindex, CCoinsViewCache &view, bool fJust
if (vtx[0].GetValueOut() > GetBlockValue(pindex->nHeight, nFees))
return error("ConnectBlock() : coinbase pays too much (actual=%"PRI64d" vs limit=%"PRI64d")", vtx[0].GetValueOut(), GetBlockValue(pindex->nHeight, nFees));
if (!control.Wait())
return DoS(100, false);
int64 nTime2 = GetTimeMicros() - nStart;
if (fBenchmark)
printf("- Verify %u txins: %.2fms (%.3fms/txin)\n", nInputs - 1, 0.001 * nTime2, nInputs <= 1 ? 0 : 0.001 * nTime2 / (nInputs-1));
if (fJustCheck)
return true;

15
src/main.h
View file

@ -53,6 +53,8 @@ inline bool MoneyRange(int64 nValue) { return (nValue >= 0 && nValue <= MAX_MONE
static const int COINBASE_MATURITY = 100;
/** Threshold for nLockTime: below this value it is interpreted as block number, otherwise as UNIX timestamp. */
static const unsigned int LOCKTIME_THRESHOLD = 500000000; // Tue Nov 5 00:53:20 1985 UTC
/** Maximum number of script-checking threads allowed */
static const int MAX_SCRIPTCHECK_THREADS = 16;
#ifdef USE_UPNP
static const int fHaveUPnP = true;
#else
@ -90,6 +92,7 @@ extern unsigned char pchMessageStart[4];
extern bool fImporting;
extern bool fReindex;
extern bool fBenchmark;
extern int nScriptCheckThreads;
extern unsigned int nCoinCacheSize;
// Settings
@ -107,6 +110,7 @@ class CCoins;
class CTxUndo;
class CCoinsView;
class CCoinsViewCache;
class CScriptCheck;
/** Register a wallet to receive updates from core */
void RegisterWallet(CWallet* pwalletIn);
@ -136,6 +140,10 @@ bool ProcessMessages(CNode* pfrom);
bool SendMessages(CNode* pto, bool fSendTrickle);
/** Run the importer thread, which deals with reindexing, loading bootstrap.dat, and whatever is passed to -loadblock */
void ThreadImport(void *parg);
/** Run an instance of the script checking thread */
void ThreadScriptCheck(void* parg);
/** Stop the script checking threads */
void ThreadScriptCheckQuit();
/** Run the miner threads */
void GenerateBitcoins(bool fGenerate, CWallet* pwallet);
/** Generate a new block, without valid proof-of-work */
@ -633,8 +641,11 @@ public:
bool HaveInputs(CCoinsViewCache &view) const;
// Check whether all inputs of this transaction are valid (no double spends, scripts & sigs, amounts)
// This does not modify the UTXO set
bool CheckInputs(CCoinsViewCache &view, bool fScriptChecks = true, unsigned int flags = SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC) const;
// This does not modify the UTXO set. If pvChecks is not NULL, script checks are pushed onto it
// instead of being performed inline.
bool CheckInputs(CCoinsViewCache &view, bool fScriptChecks = true,
unsigned int flags = SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC,
std::vector<CScriptCheck> *pvChecks = NULL) const;
// Apply the effects of this transaction on the UTXO set represented by view
bool UpdateCoins(CCoinsViewCache &view, CTxUndo &txundo, int nHeight, const uint256 &txhash) const;

1
src/net.h
View file

@ -82,6 +82,7 @@ enum threadId
THREAD_DUMPADDRESS,
THREAD_RPCHANDLER,
THREAD_IMPORT,
THREAD_SCRIPTCHECK,
THREAD_MAX
};

4
src/test/test_bitcoin.cpp
View file

@ -33,9 +33,13 @@ struct TestingSetup {
pwalletMain = new CWallet("wallet.dat");
pwalletMain->LoadWallet(fFirstRun);
RegisterWallet(pwalletMain);
nScriptCheckThreads = 3;
for (int i=0; i < nScriptCheckThreads-1; i++)
NewThread(ThreadScriptCheck, NULL);
}
~TestingSetup()
{
ThreadScriptCheckQuit();
delete pwalletMain;
pwalletMain = NULL;
delete pcoinsTip;