std::unique_ptr<WriteConcernOptions> SettingsType::getWriteConcern() const {
dassert(_key.is_initialized());
dassert(_key == BalancerDocKey);
if (isSecondaryThrottleSet() && !getSecondaryThrottle()) {
return stdx::make_unique<WriteConcernOptions>(1, WriteConcernOptions::NONE, 0);
} else if (!isMigrationWriteConcernSet()) {
// Default setting.
return nullptr;
} else {
return stdx::make_unique<WriteConcernOptions>(getMigrationWriteConcern());
}
}
BSONObj SettingsType::toBSON() const {
BSONObjBuilder builder;
if (_key) builder.append(key(), getKey());
if (_chunkSize) builder.append(chunkSize(), getChunkSize());
if (_balancerStopped) builder.append(balancerStopped(), getBalancerStopped());
if (_secondaryThrottle) {
builder.append(deprecated_secondaryThrottle(), getSecondaryThrottle());
}
if (_migrationWriteConcern) {
builder.append(migrationWriteConcern(), getMigrationWriteConcern().toBSON());
}
if (_waitForDelete) builder.append(waitForDelete(), getWaitForDelete());
return builder.obj();
}
void Balancer::run() {
Client::initThread("Balancer");
// This is the body of a BackgroundJob so if we throw here we're basically ending the balancer
// thread prematurely.
while (!inShutdown()) {
auto txn = cc().makeOperationContext();
if (!_init(txn.get())) {
log() << "will retry to initialize balancer in one minute";
sleepsecs(60);
continue;
}
break;
}
Seconds balanceRoundInterval(kBalanceRoundDefaultInterval);
while (!inShutdown()) {
auto txn = cc().makeOperationContext();
BalanceRoundDetails roundDetails;
try {
// ping has to be first so we keep things in the config server in sync
_ping(txn.get(), false);
MONGO_FAIL_POINT_BLOCK(balancerRoundIntervalSetting, scopedBalancerRoundInterval) {
const BSONObj& data = scopedBalancerRoundInterval.getData();
balanceRoundInterval = Seconds(data["sleepSecs"].numberInt());
}
// Use fresh shard state and balancer settings
Grid::get(txn.get())->shardRegistry()->reload(txn.get());
auto balancerConfig = Grid::get(txn.get())->getBalancerConfiguration();
Status refreshStatus = balancerConfig->refreshAndCheck(txn.get());
if (!refreshStatus.isOK()) {
warning() << "Skipping balancing round" << causedBy(refreshStatus);
sleepFor(balanceRoundInterval);
continue;
}
// now make sure we should even be running
if (!balancerConfig->isBalancerActive() || MONGO_FAIL_POINT(skipBalanceRound)) {
LOG(1) << "skipping balancing round because balancing is disabled";
// Ping again so scripts can determine if we're active without waiting
_ping(txn.get(), true);
sleepFor(balanceRoundInterval);
continue;
}
uassert(13258, "oids broken after resetting!", _checkOIDs(txn.get()));
{
auto scopedDistLock = grid.catalogManager(txn.get())
->distLock(txn.get(),
"balancer",
"doing balance round",
DistLockManager::kSingleLockAttemptTimeout);
if (!scopedDistLock.isOK()) {
LOG(1) << "skipping balancing round" << causedBy(scopedDistLock.getStatus());
// Ping again so scripts can determine if we're active without waiting
_ping(txn.get(), true);
sleepFor(balanceRoundInterval); // no need to wake up soon
continue;
}
LOG(1) << "*** start balancing round. "
<< "waitForDelete: " << balancerConfig->waitForDelete()
<< ", secondaryThrottle: "
<< balancerConfig->getSecondaryThrottle().toBSON();
OCCASIONALLY warnOnMultiVersion(
uassertStatusOK(_clusterStats->getStats(txn.get())));
Status status = _enforceTagRanges(txn.get());
if (!status.isOK()) {
warning() << "Failed to enforce tag ranges" << causedBy(status);
} else {
LOG(1) << "Done enforcing tag range boundaries.";
}
const auto candidateChunks = uassertStatusOK(
_chunkSelectionPolicy->selectChunksToMove(txn.get(), _balancedLastTime));
if (candidateChunks.empty()) {
LOG(1) << "no need to move any chunk";
_balancedLastTime = 0;
} else {
_balancedLastTime = _moveChunks(txn.get(),
candidateChunks,
balancerConfig->getSecondaryThrottle(),
balancerConfig->waitForDelete());
roundDetails.setSucceeded(static_cast<int>(candidateChunks.size()),
_balancedLastTime);
grid.catalogManager(txn.get())
->logAction(txn.get(), "balancer.round", "", roundDetails.toBSON());
}
LOG(1) << "*** End of balancing round";
}
// Ping again so scripts can determine if we're active without waiting
_ping(txn.get(), true);
sleepFor(_balancedLastTime ? kShortBalanceRoundInterval : balanceRoundInterval);
} catch (const std::exception& e) {
log() << "caught exception while doing balance: " << e.what();
// Just to match the opening statement if in log level 1
LOG(1) << "*** End of balancing round";
// This round failed, tell the world!
roundDetails.setFailed(e.what());
grid.catalogManager(txn.get())
->logAction(txn.get(), "balancer.round", "", roundDetails.toBSON());
// Sleep a fair amount before retrying because of the error
sleepFor(balanceRoundInterval);
}
}
}
