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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kExecutor;
#include "mongo/platform/basic.h"
#include "mongo/transport/service_executor_adaptive.h"
#include <array>
#include <random>
#include "mongo/transport/service_entry_point_utils.h"
#include "mongo/transport/service_executor_gen.h"
#include "mongo/transport/service_executor_task_names.h"
#include "mongo/util/concurrency/thread_name.h"
#include "mongo/util/duration.h"
#include "mongo/util/log.h"
#include "mongo/util/processinfo.h"
#include "mongo/util/scopeguard.h"
#include "mongo/util/str.h"
#include <asio.hpp>
namespace mongo {
namespace transport {
namespace {
constexpr auto kTotalQueued = "totalQueued"_sd;
constexpr auto kTotalExecuted = "totalExecuted"_sd;
constexpr auto kTotalTimeExecutingUs = "totalTimeExecutingMicros"_sd;
constexpr auto kTotalTimeRunningUs = "totalTimeRunningMicros"_sd;
constexpr auto kTotalTimeQueuedUs = "totalTimeQueuedMicros"_sd;
constexpr auto kThreadsInUse = "threadsInUse"_sd;
constexpr auto kThreadsRunning = "threadsRunning"_sd;
constexpr auto kThreadsPending = "threadsPending"_sd;
constexpr auto kExecutorLabel = "executor"_sd;
constexpr auto kExecutorName = "adaptive"_sd;
constexpr auto kStuckDetection = "stuckThreadsDetected"_sd;
constexpr auto kStarvation = "starvation"_sd;
constexpr auto kReserveMinimum = "belowReserveMinimum"_sd;
constexpr auto kThreadReasons = "threadCreationCauses"_sd;
int64_t ticksToMicros(TickSource::Tick ticks, TickSource* tickSource) {
invariant(tickSource->getTicksPerSecond() >= 1000000);
return tickSource->ticksTo<Microseconds>(ticks).count();
}
struct ServerParameterOptions : public ServiceExecutorAdaptive::Options {
int reservedThreads() const final {
int value = adaptiveServiceExecutorReservedThreads.load();
if (value == -1) {
value = ProcessInfo::getNumAvailableCores() / 2;
value = std::max(value, 2);
adaptiveServiceExecutorReservedThreads.store(value);
log() << "No thread count configured for executor. Using number of cores / 2: "
<< value;
}
return value;
}
Milliseconds workerThreadRunTime() const final {
return Milliseconds{adaptiveServiceExecutorRunTimeMillis.load()};
}
int runTimeJitter() const final {
return adaptiveServiceExecutorRunTimeJitterMillis.load();
}
Milliseconds stuckThreadTimeout() const final {
return Milliseconds{adaptiveServiceExecutorStuckThreadTimeoutMillis.load()};
}
Microseconds maxQueueLatency() const final {
static Nanoseconds minTimerResolution = getMinimumTimerResolution();
Microseconds value{adaptiveServiceExecutorMaxQueueLatencyMicros.load()};
if (value < minTimerResolution) {
log() << "Target MaxQueueLatencyMicros (" << value
<< ") is less than minimum timer resolution of OS (" << minTimerResolution
<< "). Using " << minTimerResolution;
value = duration_cast<Microseconds>(minTimerResolution) + Microseconds{1};
adaptiveServiceExecutorMaxQueueLatencyMicros.store(value.count());
}
return value;
}
int idlePctThreshold() const final {
return adaptiveServiceExecutorIdlePctThreshold.load();
}
int recursionLimit() const final {
return adaptiveServiceExecutorRecursionLimit.load();
}
};
} // namespace
thread_local ServiceExecutorAdaptive::ThreadState* ServiceExecutorAdaptive::_localThreadState =
nullptr;
ServiceExecutorAdaptive::ServiceExecutorAdaptive(ServiceContext* ctx, ReactorHandle reactor)
: ServiceExecutorAdaptive(
ctx, std::move(reactor), stdx::make_unique<ServerParameterOptions>()) {}
ServiceExecutorAdaptive::ServiceExecutorAdaptive(ServiceContext* ctx,
ReactorHandle reactor,
std::unique_ptr<Options> config)
: _reactorHandle(reactor),
_config(std::move(config)),
_tickSource(ctx->getTickSource()),
_lastScheduleTimer(_tickSource) {}
ServiceExecutorAdaptive::~ServiceExecutorAdaptive() {
invariant(!_isRunning.load());
}
Status ServiceExecutorAdaptive::start() {
invariant(!_isRunning.load());
_isRunning.store(true);
_controllerThread = stdx::thread(&ServiceExecutorAdaptive::_controllerThreadRoutine, this);
for (auto i = 0; i < _config->reservedThreads(); i++) {
_startWorkerThread(ThreadCreationReason::kReserveMinimum);
}
return Status::OK();
}
Status ServiceExecutorAdaptive::shutdown(Milliseconds timeout) {
if (!_isRunning.load())
return Status::OK();
_isRunning.store(false);
_scheduleCondition.notify_one();
_controllerThread.join();
stdx::unique_lock<stdx::mutex> lk(_threadsMutex);
_reactorHandle->stop();
bool result =
_deathCondition.wait_for(lk, timeout.toSystemDuration(), [&] { return _threads.empty(); });
return result
? Status::OK()
: Status(ErrorCodes::Error::ExceededTimeLimit,
"adaptive executor couldn't shutdown all worker threads within time limit.");
}
Status ServiceExecutorAdaptive::schedule(ServiceExecutorAdaptive::Task task,
ScheduleFlags flags,
ServiceExecutorTaskName taskName) {
auto scheduleTime = _tickSource->getTicks();
auto pendingCounterPtr = (flags & kDeferredTask) ? &_deferredTasksQueued : &_tasksQueued;
pendingCounterPtr->addAndFetch(1);
if (!_isRunning.load()) {
return {ErrorCodes::ShutdownInProgress, "Executor is not running"};
}
auto wrappedTask =
[this, task = std::move(task), scheduleTime, pendingCounterPtr, taskName, flags](
auto status) {
pendingCounterPtr->subtractAndFetch(1);
auto start = _tickSource->getTicks();
_totalSpentQueued.addAndFetch(start - scheduleTime);
_localThreadState->threadMetrics[static_cast<size_t>(taskName)]
._totalSpentQueued.addAndFetch(start - scheduleTime);
if (_localThreadState->recursionDepth++ == 0) {
_localThreadState->executing.markRunning();
_threadsInUse.addAndFetch(1);
}
const auto guard = makeGuard([this, taskName] {
if (--_localThreadState->recursionDepth == 0) {
_localThreadState->executingCurRun +=
_localThreadState->executing.markStopped();
_threadsInUse.subtractAndFetch(1);
}
_totalExecuted.addAndFetch(1);
_localThreadState->threadMetrics[static_cast<size_t>(taskName)]
._totalExecuted.addAndFetch(1);
});
TickTimer _localTimer(_tickSource);
task();
_localThreadState->threadMetrics[static_cast<size_t>(taskName)]
._totalSpentExecuting.addAndFetch(_localTimer.sinceStartTicks());
};
// Dispatching a task on the io_context will run the task immediately, and may run it
// on the current thread (if the current thread is running the io_context right now).
//
// Posting a task on the io_context will run the task without recursion.
//
// If the task is allowed to recurse and we are not over the depth limit, dispatch it so it
// can be called immediately and recursively.
if ((flags & kMayRecurse) &&
(_localThreadState->recursionDepth + 1 < _config->recursionLimit())) {
_reactorHandle->dispatch(std::move(wrappedTask));
} else {
_reactorHandle->schedule(std::move(wrappedTask));
}
_lastScheduleTimer.reset();
_totalQueued.addAndFetch(1);
_accumulatedMetrics[static_cast<size_t>(taskName)]._totalQueued.addAndFetch(1);
// Deferred tasks never count against the thread starvation avoidance. For other tasks, we
// notify the controller thread that a task has been scheduled and we should monitor thread
// starvation.
if (_isStarved() && !(flags & kDeferredTask)) {
_starvationCheckRequests.addAndFetch(1);
_scheduleCondition.notify_one();
}
return Status::OK();
}
bool ServiceExecutorAdaptive::_isStarved() const {
// If threads are still starting, then assume we won't be starved pretty soon, return false
if (_threadsPending.load() > 0)
return false;
auto tasksQueued = _tasksQueued.load();
// If there are no pending tasks, then we definitely aren't starved
if (tasksQueued == 0)
return false;
// The available threads is the number that are running - the number that are currently
// executing
auto available = _threadsRunning.load() - _threadsInUse.load();
return (tasksQueued > available);
}
/*
* The pool of worker threads can become unhealthy in several ways, and the controller thread
* tries to keep the pool healthy by starting new threads when it is:
*
* Stuck: All threads are running a long-running task that's waiting on a network event, but
* there are no threads available to process network events. The thread pool cannot make progress
* without intervention.
*
* Starved: All threads are saturated with tasks and new tasks are having to queue for longer
* than the configured maxQueueLatency().
*
* Below reserve: An error has occurred and there are fewer threads than the reserved minimum.
*
* While the executor is running, it runs in a loop waiting to be woken up by schedule() or a
* timeout to occur. When it wakes up, it ensures that:
* - The thread pool is not stuck longer than the configured stuckThreadTimeout(). If it is, then
* start a new thread and wait to be woken up again (or time out again and redo stuck thread
* detection).
* - The number of threads is >= the reservedThreads() value. If it isn't, then start as many
* threads as necessary.
* - Checking for starvation when requested by schedule(), and starting new threads if the
* pool is saturated and is starved longer than the maxQueueLatency() after being woken up
* by schedule().
*/
void ServiceExecutorAdaptive::_controllerThreadRoutine() {
stdx::mutex noopLock;
setThreadName("worker-controller"_sd);
// Setup the timers/timeout values for stuck thread detection.
TickTimer sinceLastStuckThreadCheck(_tickSource);
auto stuckThreadTimeout = _config->stuckThreadTimeout();
// Get the initial values for our utilization percentage calculations
auto getTimerTotals = [this]() {
stdx::unique_lock<stdx::mutex> lk(_threadsMutex);
auto first = _getThreadTimerTotal(ThreadTimer::kExecuting, lk);
auto second = _getThreadTimerTotal(ThreadTimer::kRunning, lk);
return std::make_pair(first, second);
};
TickSource::Tick lastSpentExecuting, lastSpentRunning;
std::tie(lastSpentExecuting, lastSpentRunning) = getTimerTotals();
while (_isRunning.load()) {
// We want to wait for schedule() to wake us up, or for the stuck thread timeout to pass.
// So the timeout is the current stuck thread timeout - the last time we did stuck thread
// detection.
auto timeout = stuckThreadTimeout - sinceLastStuckThreadCheck.sinceStart();
bool maybeStarved = false;
// If the timeout is less than a millisecond then don't bother to go to sleep to wait for
// it, just do the stuck thread detection now.
if (timeout > Milliseconds{0}) {
stdx::unique_lock<decltype(noopLock)> scheduleLk(noopLock);
int checkRequests = 0;
maybeStarved = _scheduleCondition.wait_for(
scheduleLk, timeout.toSystemDuration(), [this, &checkRequests] {
if (!_isRunning.load())
return false;
checkRequests = _starvationCheckRequests.load();
return (checkRequests > 0);
});
_starvationCheckRequests.subtractAndFetch(checkRequests);
}
// If the executor has stopped, then stop the controller altogether
if (!_isRunning.load())
break;
if (sinceLastStuckThreadCheck.sinceStart() >= stuckThreadTimeout) {
// Reset our timer so we know how long to sleep for the next time around;
sinceLastStuckThreadCheck.reset();
// Each call to schedule updates the last schedule ticks so we know the last time a
// task was scheduled
Milliseconds sinceLastSchedule = _lastScheduleTimer.sinceStart();
// If the number of tasks executing is the number of threads running (that is all
// threads are currently busy), and the last time a task was able to be scheduled was
// longer than our wait timeout, then we can assume all threads are stuck and we should
// start a new thread to unblock the pool.
//
if ((_threadsInUse.load() == _threadsRunning.load()) &&
(sinceLastSchedule >= stuckThreadTimeout)) {
// When the executor is stuck, we halve the stuck thread timeout to be more
// aggressive the next time out unsticking the executor, and then start a new
// thread to unblock the executor for now.
stuckThreadTimeout /= 2;
stuckThreadTimeout = std::max(Milliseconds{10}, stuckThreadTimeout);
log() << "Detected blocked worker threads, "
<< "starting new thread to unblock service executor. "
<< "Stuck thread timeout now: " << stuckThreadTimeout;
_startWorkerThread(ThreadCreationReason::kStuckDetection);
// Since we've just started a worker thread, then we know that the executor isn't
// starved, so just loop back around to wait for the next control event.
continue;
}
// If the executor wasn't stuck, then we should back off our stuck thread timeout back
// towards the configured value.
auto newStuckThreadTimeout = stuckThreadTimeout + (stuckThreadTimeout / 2);
newStuckThreadTimeout = std::min(_config->stuckThreadTimeout(), newStuckThreadTimeout);
if (newStuckThreadTimeout != stuckThreadTimeout) {
LOG(1) << "Increasing stuck thread timeout to " << newStuckThreadTimeout;
stuckThreadTimeout = newStuckThreadTimeout;
}
}
auto threadsRunning = _threadsRunning.load();
if (threadsRunning < _config->reservedThreads()) {
log() << "Starting " << _config->reservedThreads() - threadsRunning
<< " to replenish reserved worker threads";
while (_threadsRunning.load() < _config->reservedThreads()) {
_startWorkerThread(ThreadCreationReason::kReserveMinimum);
}
}
// If we were notified by schedule() to do starvation checking, then we first need to
// calculate the overall utilization of the executor.
if (maybeStarved) {
// Get the difference between the amount of time the executor has spent waiting for/
// running tasks since the last time we measured.
TickSource::Tick spentExecuting, spentRunning;
std::tie(spentExecuting, spentRunning) = getTimerTotals();
auto diffExecuting = spentExecuting - lastSpentExecuting;
auto diffRunning = spentRunning - lastSpentRunning;
double utilizationPct;
// If we spent zero time running then the executor was fully idle and our utilization
// is zero percent
if (spentRunning == 0 || diffRunning == 0)
utilizationPct = 0.0;
else {
lastSpentExecuting = spentExecuting;
lastSpentRunning = spentRunning;
utilizationPct = diffExecuting / static_cast<double>(diffRunning);
utilizationPct *= 100;
}
// If the utilization percentage is less than our threshold then we don't want to
// do anything because the threads are not actually saturated with work.
if (utilizationPct < _config->idlePctThreshold()) {
continue;
}
}
// While there are threads that are still starting up, wait for the max queue latency,
// up to the current stuck thread timeout.
do {
stdx::this_thread::sleep_for(_config->maxQueueLatency().toSystemDuration());
} while ((_threadsPending.load() > 0) &&
(sinceLastStuckThreadCheck.sinceStart() < stuckThreadTimeout));
// If the number of pending tasks is greater than the number of running threads minus the
// number of tasks executing (the number of free threads), then start a new worker to
// avoid starvation.
if (_isStarved()) {
log() << "Starting worker thread to avoid starvation.";
_startWorkerThread(ThreadCreationReason::kStarvation);
}
}
}
void ServiceExecutorAdaptive::_startWorkerThread(ThreadCreationReason reason) {
stdx::unique_lock<stdx::mutex> lk(_threadsMutex);
auto it = _threads.emplace(_threads.begin(), _tickSource);
auto num = _threads.size();
_threadsPending.addAndFetch(1);
_threadsRunning.addAndFetch(1);
_threadStartCounters[static_cast<size_t>(reason)] += 1;
lk.unlock();
const auto launchResult =
launchServiceWorkerThread([this, num, it] { _workerThreadRoutine(num, it); });
if (!launchResult.isOK()) {
warning() << "Failed to launch new worker thread: " << launchResult;
lk.lock();
_threadsPending.subtractAndFetch(1);
_threadsRunning.subtractAndFetch(1);
_threadStartCounters[static_cast<size_t>(reason)] -= 1;
_threads.erase(it);
}
}
Milliseconds ServiceExecutorAdaptive::_getThreadJitter() const {
static stdx::mutex jitterMutex;
static std::default_random_engine randomEngine = [] {
std::random_device seed;
return std::default_random_engine(seed());
}();
auto jitterParam = _config->runTimeJitter();
if (jitterParam == 0)
return Milliseconds{0};
std::uniform_int_distribution<> jitterDist(-jitterParam, jitterParam);
stdx::lock_guard<stdx::mutex> lk(jitterMutex);
auto jitter = jitterDist(randomEngine);
if (jitter > _config->workerThreadRunTime().count())
jitter = 0;
return Milliseconds{jitter};
}
void ServiceExecutorAdaptive::_accumulateTaskMetrics(MetricsArray* outArray,
const MetricsArray& inputArray) const {
for (auto it = inputArray.begin(); it != inputArray.end(); ++it) {
auto taskName = static_cast<ServiceExecutorTaskName>(std::distance(inputArray.begin(), it));
auto& output = outArray->at(static_cast<size_t>(taskName));
output._totalSpentExecuting.addAndFetch(it->_totalSpentExecuting.load());
output._totalSpentQueued.addAndFetch(it->_totalSpentQueued.load());
output._totalExecuted.addAndFetch(it->_totalExecuted.load());
output._totalQueued.addAndFetch(it->_totalQueued.load());
}
}
void ServiceExecutorAdaptive::_accumulateAllTaskMetrics(
MetricsArray* outputMetricsArray, const stdx::unique_lock<stdx::mutex>& lk) const {
_accumulateTaskMetrics(outputMetricsArray, _accumulatedMetrics);
for (auto& thread : _threads) {
_accumulateTaskMetrics(outputMetricsArray, thread.threadMetrics);
}
}
TickSource::Tick ServiceExecutorAdaptive::_getThreadTimerTotal(
ThreadTimer which, const stdx::unique_lock<stdx::mutex>& lk) const {
TickSource::Tick accumulator;
switch (which) {
case ThreadTimer::kRunning:
accumulator = _pastThreadsSpentRunning.load();
break;
case ThreadTimer::kExecuting:
accumulator = _pastThreadsSpentExecuting.load();
break;
}
for (auto& thread : _threads) {
switch (which) {
case ThreadTimer::kRunning:
accumulator += thread.running.totalTime();
break;
case ThreadTimer::kExecuting:
accumulator += thread.executing.totalTime();
break;
}
}
return accumulator;
}
void ServiceExecutorAdaptive::_workerThreadRoutine(
int threadId, ServiceExecutorAdaptive::ThreadList::iterator state) {
_threadsPending.subtractAndFetch(1);
_localThreadState = &(*state);
{
std::string threadName = str::stream() << "worker-" << threadId;
setThreadName(threadName);
}
log() << "Started new database worker thread " << threadId;
bool guardThreadsRunning = true;
const auto guard = makeGuard([this, &guardThreadsRunning, state] {
if (guardThreadsRunning)
_threadsRunning.subtractAndFetch(1);
_pastThreadsSpentRunning.addAndFetch(state->running.totalTime());
_pastThreadsSpentExecuting.addAndFetch(state->executing.totalTime());
_accumulateTaskMetrics(&_accumulatedMetrics, state->threadMetrics);
{
stdx::lock_guard<stdx::mutex> lk(_threadsMutex);
_threads.erase(state);
}
_deathCondition.notify_one();
});
auto jitter = _getThreadJitter();
while (_isRunning.load()) {
// We don't want all the threads to start/stop running at exactly the same time, so the
// jitter setParameter adds/removes a random small amount of time to the runtime.
Milliseconds runTime = _config->workerThreadRunTime() + jitter;
dassert(runTime.count() > 0);
// Reset ticksSpentExecuting timer
state->executingCurRun = 0;
// If we're still "pending" only try to run one task, that way the controller will
// know that it's okay to start adding threads to avoid starvation again.
state->running.markRunning();
_reactorHandle->runFor(runTime);
auto spentRunning = state->running.markStopped();
// If we spent less than our idle threshold actually running tasks then exit the thread.
// This is a helper lambda to perform that calculation.
const auto calculatePctExecuting = [&spentRunning, &state]() {
// This time measurement doesn't include time spent running network callbacks,
// so the threshold is lower than you'd expect.
dassert(spentRunning < std::numeric_limits<double>::max());
// First get the ratio of ticks spent executing to ticks spent running. We
// expect this to be <= 1.0
double executingToRunning = state->executingCurRun / static_cast<double>(spentRunning);
// Multiply that by 100 to get the percentage of time spent executing tasks. We
// expect this to be <= 100.
executingToRunning *= 100;
dassert(executingToRunning <= 100);
return static_cast<int>(executingToRunning);
};
bool terminateThread = false;
int pctExecuting;
int runningThreads;
// Make sure we don't terminate threads below the reserved threshold. As there can be
// several worker threads concurrently in this terminate logic atomically reduce the threads
// one by one to avoid racing using a lockless compare-and-swap loop where we retry if there
// is contention on the atomic.
do {
runningThreads = _threadsRunning.load();
if (runningThreads <= _config->reservedThreads()) {
terminateThread = false;
break; // keep thread
}
if (!terminateThread) {
pctExecuting = calculatePctExecuting();
terminateThread = pctExecuting <= _config->idlePctThreshold();
}
} while (terminateThread &&
_threadsRunning.compareAndSwap(runningThreads, runningThreads - 1) !=
runningThreads);
if (terminateThread) {
log() << "Thread was only executing tasks " << pctExecuting << "% over the last "
<< runTime << ". Exiting thread.";
// Because we've already modified _threadsRunning, make sure the thread guard also
// doesn't do it.
guardThreadsRunning = false;
break;
}
}
}
StringData ServiceExecutorAdaptive::_threadStartedByToString(
ServiceExecutorAdaptive::ThreadCreationReason reason) {
switch (reason) {
case ThreadCreationReason::kStuckDetection:
return kStuckDetection;
case ThreadCreationReason::kStarvation:
return kStarvation;
case ThreadCreationReason::kReserveMinimum:
return kReserveMinimum;
default:
MONGO_UNREACHABLE;
}
}
void ServiceExecutorAdaptive::appendStats(BSONObjBuilder* bob) const {
stdx::unique_lock<stdx::mutex> lk(_threadsMutex);
*bob << kExecutorLabel << kExecutorName //
<< kTotalQueued << _totalQueued.load() //
<< kTotalExecuted << _totalExecuted.load() //
<< kThreadsInUse << _threadsInUse.load() //
<< kTotalTimeRunningUs //
<< ticksToMicros(_getThreadTimerTotal(ThreadTimer::kRunning, lk), _tickSource) //
<< kTotalTimeExecutingUs //
<< ticksToMicros(_getThreadTimerTotal(ThreadTimer::kExecuting, lk), _tickSource) //
<< kTotalTimeQueuedUs << ticksToMicros(_totalSpentQueued.load(), _tickSource) //
<< kThreadsRunning << _threadsRunning.load() //
<< kThreadsPending << _threadsPending.load();
BSONObjBuilder threadStartReasons(bob->subobjStart(kThreadReasons));
for (size_t i = 0; i < _threadStartCounters.size(); i++) {
threadStartReasons << _threadStartedByToString(static_cast<ThreadCreationReason>(i))
<< _threadStartCounters[i];
}
threadStartReasons.doneFast();
BSONObjBuilder metricsByTask(bob->subobjStart("metricsByTask"));
MetricsArray totalMetrics;
_accumulateAllTaskMetrics(&totalMetrics, lk);
lk.unlock();
for (auto it = totalMetrics.begin(); it != totalMetrics.end(); ++it) {
auto taskName =
static_cast<ServiceExecutorTaskName>(std::distance(totalMetrics.begin(), it));
auto taskNameString = taskNameToString(taskName);
BSONObjBuilder subSection(metricsByTask.subobjStart(taskNameString));
subSection << kTotalQueued << it->_totalQueued.load() << kTotalExecuted
<< it->_totalExecuted.load() << kTotalTimeExecutingUs
<< ticksToMicros(it->_totalSpentExecuting.load(), _tickSource)
<< kTotalTimeQueuedUs
<< ticksToMicros(it->_totalSpentQueued.load(), _tickSource);
subSection.doneFast();
}
metricsByTask.doneFast();
}
} // namespace transport
} // namespace mongo
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