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foundationdb/fdbserver/RkTagThrottleCollection.cpp

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/*
* RkTagThrottleCollection.cpp
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
*
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "fdbserver/Knobs.h"
#include "fdbserver/RkTagThrottleCollection.h"
double RkTagThrottleCollection::RkTagThrottleData::getTargetRate(Optional<double> requestRate) const {
if (limits.tpsRate == 0.0 || !requestRate.present() || requestRate.get() == 0.0 || !rateSet) {
return limits.tpsRate;
} else {
return std::min(limits.tpsRate, (limits.tpsRate / requestRate.get()) * clientRate.smoothTotal());
}
}
Optional<double> RkTagThrottleCollection::RkTagThrottleData::updateAndGetClientRate(Optional<double> requestRate) {
if (limits.expiration > now()) {
double targetRate = getTargetRate(requestRate);
if (targetRate == std::numeric_limits<double>::max()) {
rateSet = false;
return targetRate;
}
if (!rateSet) {
rateSet = true;
clientRate.reset(targetRate);
} else {
clientRate.setTotal(targetRate);
}
double rate = clientRate.smoothTotal();
ASSERT_GE(rate, 0);
return rate;
} else {
CODE_PROBE(true, "Get throttle rate for expired throttle");
rateSet = false;
return Optional<double>();
}
}
RkTagThrottleCollection::RkTagThrottleCollection(RkTagThrottleCollection&& other) {
autoThrottledTags = std::move(other.autoThrottledTags);
manualThrottledTags = std::move(other.manualThrottledTags);
tagData = std::move(other.tagData);
}
RkTagThrottleCollection& RkTagThrottleCollection::RkTagThrottleCollection::operator=(RkTagThrottleCollection&& other) {
autoThrottledTags = std::move(other.autoThrottledTags);
manualThrottledTags = std::move(other.manualThrottledTags);
tagData = std::move(other.tagData);
return *this;
}
double RkTagThrottleCollection::computeTargetTpsRate(double currentBusyness,
double targetBusyness,
double requestRate) {
ASSERT_GT(currentBusyness, 0);
if (targetBusyness < 1) {
double targetFraction = targetBusyness * (1 - currentBusyness) / ((1 - targetBusyness) * currentBusyness);
return requestRate * targetFraction;
} else {
return std::numeric_limits<double>::max();
}
}
Optional<double> RkTagThrottleCollection::autoThrottleTag(UID id,
TransactionTag const& tag,
double fractionalBusyness,
Optional<double> tpsRate,
Optional<double> expiration) {
ASSERT(!tpsRate.present() || tpsRate.get() >= 0);
ASSERT(!expiration.present() || expiration.get() > now());
auto itr = autoThrottledTags.find(tag);
bool present = (itr != autoThrottledTags.end());
if (!present) {
if (autoThrottledTags.size() >= SERVER_KNOBS->MAX_AUTO_THROTTLED_TRANSACTION_TAGS) {
CODE_PROBE(true, "Reached auto-throttle limit");
return Optional<double>();
}
itr = autoThrottledTags.try_emplace(tag).first;
initializeTag(tag);
} else if (itr->second.limits.expiration <= now()) {
CODE_PROBE(true, "Re-throttling expired tag that hasn't been cleaned up");
present = false;
itr->second = RkTagThrottleData();
}
auto& throttle = itr->second;
if (!tpsRate.present()) {
if (now() <= throttle.created + SERVER_KNOBS->AUTO_TAG_THROTTLE_START_AGGREGATION_TIME) {
tpsRate = std::numeric_limits<double>::max();
if (present) {
return Optional<double>();
}
} else if (now() <= throttle.lastUpdated + SERVER_KNOBS->AUTO_TAG_THROTTLE_UPDATE_FREQUENCY) {
CODE_PROBE(true, "Tag auto-throttled too quickly");
return Optional<double>();
} else {
tpsRate = computeTargetTpsRate(fractionalBusyness,
SERVER_KNOBS->AUTO_THROTTLE_TARGET_TAG_BUSYNESS,
tagData[tag].requestRate.smoothRate());
if (throttle.limits.expiration > now() && tpsRate.get() >= throttle.limits.tpsRate) {
CODE_PROBE(true, "Tag auto-throttle rate increase attempt while active");
return Optional<double>();
}
throttle.lastUpdated = now();
if (tpsRate.get() < throttle.limits.tpsRate) {
throttle.lastReduced = now();
}
}
}
if (!expiration.present()) {
expiration = now() + SERVER_KNOBS->AUTO_TAG_THROTTLE_DURATION;
}
ASSERT(tpsRate.present() && tpsRate.get() >= 0);
throttle.limits.tpsRate = tpsRate.get();
throttle.limits.expiration = expiration.get();
Optional<double> clientRate = throttle.updateAndGetClientRate(getRequestRate(tag));
TraceEvent("RkSetAutoThrottle", id)
.detail("Tag", tag)
.detail("TargetRate", tpsRate.get())
.detail("Expiration", expiration.get() - now())
.detail("ClientRate", clientRate)
.detail("Created", now() - throttle.created)
.detail("LastUpdate", now() - throttle.lastUpdated)
.detail("LastReduced", now() - throttle.lastReduced);
if (tpsRate.get() != std::numeric_limits<double>::max()) {
return tpsRate.get();
} else {
return Optional<double>();
}
}
void RkTagThrottleCollection::manualThrottleTag(UID id,
TransactionTag const& tag,
TransactionPriority priority,
double tpsRate,
double expiration,
Optional<ClientTagThrottleLimits> const& oldLimits) {
ASSERT(tpsRate >= 0);
ASSERT(expiration > now());
auto& priorityThrottleMap = manualThrottledTags[tag];
auto result = priorityThrottleMap.try_emplace(priority);
initializeTag(tag);
ASSERT(result.second); // Updating to the map is done by copying the whole map
result.first->second.limits.tpsRate = tpsRate;
result.first->second.limits.expiration = expiration;
if (!oldLimits.present()) {
CODE_PROBE(true, "Transaction tag manually throttled");
TraceEvent("RatekeeperAddingManualThrottle", id)
.detail("Tag", tag)
.detail("Rate", tpsRate)
.detail("Priority", transactionPriorityToString(priority))
.detail("SecondsToExpiration", expiration - now());
} else if (oldLimits.get().tpsRate != tpsRate || oldLimits.get().expiration != expiration) {
CODE_PROBE(true, "Manual transaction tag throttle updated");
TraceEvent("RatekeeperUpdatingManualThrottle", id)
.detail("Tag", tag)
.detail("Rate", tpsRate)
.detail("Priority", transactionPriorityToString(priority))
.detail("SecondsToExpiration", expiration - now());
}
Optional<double> clientRate = result.first->second.updateAndGetClientRate(getRequestRate(tag));
ASSERT(clientRate.present());
}
Optional<ClientTagThrottleLimits> RkTagThrottleCollection::getManualTagThrottleLimits(TransactionTag const& tag,
TransactionPriority priority) {
auto itr = manualThrottledTags.find(tag);
if (itr != manualThrottledTags.end()) {
auto priorityItr = itr->second.find(priority);
if (priorityItr != itr->second.end()) {
return priorityItr->second.limits;
}
}
return Optional<ClientTagThrottleLimits>();
}
PrioritizedTransactionTagMap<ClientTagThrottleLimits> RkTagThrottleCollection::getClientRates(
bool autoThrottlingEnabled) {
PrioritizedTransactionTagMap<ClientTagThrottleLimits> clientRates;
for (auto tagItr = tagData.begin(); tagItr != tagData.end();) {
bool tagPresent = false;
double requestRate = tagItr->second.requestRate.smoothRate();
auto manualItr = manualThrottledTags.find(tagItr->first);
if (manualItr != manualThrottledTags.end()) {
Optional<ClientTagThrottleLimits> manualClientRate;
for (auto priority = allTransactionPriorities.rbegin(); !(priority == allTransactionPriorities.rend());
++priority) {
auto priorityItr = manualItr->second.find(*priority);
if (priorityItr != manualItr->second.end()) {
Optional<double> priorityClientRate = priorityItr->second.updateAndGetClientRate(requestRate);
if (!priorityClientRate.present()) {
CODE_PROBE(true, "Manual priority throttle expired");
priorityItr = manualItr->second.erase(priorityItr);
} else {
if (!manualClientRate.present() || manualClientRate.get().tpsRate > priorityClientRate.get()) {
manualClientRate = ClientTagThrottleLimits(priorityClientRate.get(),
priorityItr->second.limits.expiration);
} else {
CODE_PROBE(true, "Manual throttle overriden by higher priority");
}
++priorityItr;
}
}
if (manualClientRate.present()) {
tagPresent = true;
CODE_PROBE(true, "Using manual throttle");
clientRates[*priority][tagItr->first] = manualClientRate.get();
}
}
if (manualItr->second.empty()) {
CODE_PROBE(true, "All manual throttles expired");
manualThrottledTags.erase(manualItr);
break;
}
}
auto autoItr = autoThrottledTags.find(tagItr->first);
if (autoItr != autoThrottledTags.end()) {
Optional<double> autoClientRate = autoItr->second.updateAndGetClientRate(requestRate);
if (autoClientRate.present()) {
double adjustedRate = autoClientRate.get();
double rampStartTime = autoItr->second.lastReduced + SERVER_KNOBS->AUTO_TAG_THROTTLE_DURATION -
SERVER_KNOBS->AUTO_TAG_THROTTLE_RAMP_UP_TIME;
if (now() >= rampStartTime && adjustedRate != std::numeric_limits<double>::max()) {
CODE_PROBE(true, "Tag auto-throttle ramping up");
double targetBusyness = SERVER_KNOBS->AUTO_THROTTLE_TARGET_TAG_BUSYNESS;
if (targetBusyness == 0) {
targetBusyness = 0.01;
}
double rampLocation = (now() - rampStartTime) / SERVER_KNOBS->AUTO_TAG_THROTTLE_RAMP_UP_TIME;
adjustedRate =
computeTargetTpsRate(targetBusyness, pow(targetBusyness, 1 - rampLocation), adjustedRate);
}
tagPresent = true;
if (autoThrottlingEnabled) {
auto result = clientRates[TransactionPriority::DEFAULT].try_emplace(
tagItr->first, adjustedRate, autoItr->second.limits.expiration);
if (!result.second && result.first->second.tpsRate > adjustedRate) {
result.first->second = ClientTagThrottleLimits(adjustedRate, autoItr->second.limits.expiration);
} else {
CODE_PROBE(true, "Auto throttle overriden by manual throttle");
}
clientRates[TransactionPriority::BATCH][tagItr->first] =
ClientTagThrottleLimits(0, autoItr->second.limits.expiration);
}
} else {
ASSERT(autoItr->second.limits.expiration <= now());
CODE_PROBE(true, "Auto throttle expired");
if (BUGGIFY) { // Temporarily extend the window between expiration and cleanup
tagPresent = true;
} else {
autoThrottledTags.erase(autoItr);
}
}
}
if (!tagPresent) {
CODE_PROBE(true, "All tag throttles expired");
tagItr = tagData.erase(tagItr);
} else {
++tagItr;
}
}
return clientRates;
}
void RkTagThrottleCollection::addRequests(TransactionTag const& tag, int requests) {
if (requests > 0) {
CODE_PROBE(true, "Requests reported for throttled tag");
auto tagItr = tagData.try_emplace(tag);
tagItr.first->second.requestRate.addDelta(requests);
double requestRate = tagItr.first->second.requestRate.smoothRate();
auto autoItr = autoThrottledTags.find(tag);
if (autoItr != autoThrottledTags.end()) {
autoItr->second.updateAndGetClientRate(requestRate);
}
auto manualItr = manualThrottledTags.find(tag);
if (manualItr != manualThrottledTags.end()) {
for (auto& [priority, tagThrottleData] : manualItr->second) {
tagThrottleData.updateAndGetClientRate(requestRate);
}
}
}
}
Optional<double> RkTagThrottleCollection::getRequestRate(TransactionTag const& tag) {
auto itr = tagData.find(tag);
if (itr != tagData.end()) {
return itr->second.requestRate.smoothRate();
}
return Optional<double>();
}
int64_t RkTagThrottleCollection::manualThrottleCount() const {
int64_t count = 0;
for (auto itr = manualThrottledTags.begin(); itr != manualThrottledTags.end(); ++itr) {
count += itr->second.size();
}
return count;
}
void RkTagThrottleCollection::incrementBusyTagCount(TagThrottledReason reason) {
if (reason == TagThrottledReason::BUSY_READ) {
++busyReadTagCount;
} else if (reason == TagThrottledReason::BUSY_WRITE) {
++busyWriteTagCount;
} else {
ASSERT(false);
}
}
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