opm-simulators/opm/models/parallel/tasklets.cpp
2024-09-04 12:06:21 +02:00

206 lines
6.2 KiB
C++

// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
/*
This file is part of the Open Porous Media project (OPM).
OPM is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
OPM 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
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with OPM. If not, see <http://www.gnu.org/licenses/>.
Consult the COPYING file in the top-level source directory of this
module for the precise wording of the license and the list of
copyright holders.
*/
#include <config.h>
#include <opm/models/parallel/tasklets.hpp>
#include <atomic>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <queue>
#include <stdexcept>
#include <thread>
namespace Opm {
thread_local TaskletRunner* TaskletRunner::taskletRunner_ = nullptr;
thread_local int TaskletRunner::workerThreadIndex_ = -1;
TaskletRunner::BarrierTasklet::BarrierTasklet(unsigned numWorkers)
: TaskletInterface(/*refCount=*/numWorkers)
{
numWorkers_ = numWorkers;
numWaiting_ = 0;
}
void TaskletRunner::BarrierTasklet::run()
{
wait();
}
void TaskletRunner::BarrierTasklet::wait()
{
std::unique_lock<std::mutex> lock(barrierMutex_);
numWaiting_ += 1;
if (numWaiting_ >= numWorkers_ + 1) {
lock.unlock();
barrierCondition_.notify_all();
}
else {
const auto& areAllWaiting =
[this]() -> bool
{ return this->numWaiting_ >= this->numWorkers_ + 1; };
barrierCondition_.wait(lock, /*predicate=*/areAllWaiting);
}
}
TaskletRunner::TaskletRunner(unsigned numWorkers)
{
threads_.resize(numWorkers);
for (unsigned i = 0; i < numWorkers; ++i)
// create a worker thread
threads_[i].reset(new std::thread(startWorkerThread_, this, i));
}
TaskletRunner::~TaskletRunner()
{
if (threads_.size() > 0) {
// dispatch a tasklet which will terminate the worker thread
dispatch(std::make_shared<TerminateThreadTasklet>());
// wait until all worker threads have terminated
for (auto& thread : threads_)
thread->join();
}
}
bool TaskletRunner::failure() const
{
return this->failureFlag_.load(std::memory_order_relaxed);
}
int TaskletRunner::workerThreadIndex() const
{
if (TaskletRunner::taskletRunner_ != this)
return -1;
return TaskletRunner::workerThreadIndex_;
}
void TaskletRunner::dispatch(std::shared_ptr<TaskletInterface> tasklet)
{
if (threads_.empty()) {
// run the tasklet immediately in synchronous mode.
while (tasklet->referenceCount() > 0) {
tasklet->dereference();
try {
tasklet->run();
}
catch (const std::exception& e) {
std::cerr << "ERROR: Uncaught std::exception when running tasklet: " << e.what() << ". Trying to continue.\n";
failureFlag_.store(true, std::memory_order_relaxed);
}
catch (...) {
std::cerr << "ERROR: Uncaught exception (general type) when running tasklet. Trying to continue.\n";
failureFlag_.store(true, std::memory_order_relaxed);
}
}
}
else {
// lock mutex for the tasklet queue to make sure that nobody messes with the
// task queue
taskletQueueMutex_.lock();
// add the tasklet to the queue
taskletQueue_.push(tasklet);
taskletQueueMutex_.unlock();
workAvailableCondition_.notify_all();
}
}
void TaskletRunner::barrier()
{
unsigned numWorkers = threads_.size();
if (numWorkers == 0)
// nothing needs to be done to implement a barrier in synchronous mode
return;
// dispatch a barrier tasklet and wait until it has been run by the worker thread
auto barrierTasklet = std::make_shared<BarrierTasklet>(numWorkers);
dispatch(barrierTasklet);
barrierTasklet->wait();
}
void TaskletRunner::startWorkerThread_(TaskletRunner* taskletRunner, int workerThreadIndex)
{
TaskletRunner::taskletRunner_ = taskletRunner;
TaskletRunner::workerThreadIndex_ = workerThreadIndex;
taskletRunner->run_();
}
void TaskletRunner::run_()
{
while (true) {
// wait until tasklets have been pushed to the queue. first we need to lock
// mutex for access to taskletQueue_
std::unique_lock<std::mutex> lock(taskletQueueMutex_);
const auto& workIsAvailable =
[this]() -> bool
{ return !taskletQueue_.empty(); };
if (!workIsAvailable())
workAvailableCondition_.wait(lock, /*predicate=*/workIsAvailable);
// remove tasklet from queue
std::shared_ptr<TaskletInterface> tasklet = taskletQueue_.front();
// if tasklet is an end marker, terminate the thread and DO NOT remove the
// tasklet.
if (tasklet->isEndMarker()) {
if(taskletQueue_.size() > 1)
throw std::logic_error("TaskletRunner: Not all queued tasklets were executed");
taskletQueueMutex_.unlock();
return;
}
tasklet->dereference();
if (tasklet->referenceCount() == 0)
// remove tasklets from the queue as soon as their reference count
// reaches zero, i.e. the tasklet has been run often enough.
taskletQueue_.pop();
lock.unlock();
// execute tasklet
try {
tasklet->run();
}
catch (const std::exception& e) {
std::cerr << "ERROR: Uncaught std::exception when running tasklet: " << e.what() << ".\n";
failureFlag_.store(true, std::memory_order_relaxed);
}
catch (...) {
std::cerr << "ERROR: Uncaught exception when running tasklet.\n";
failureFlag_.store(true, std::memory_order_relaxed);
}
}
}
} // end namespace Opm