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Fix potential data race on spin_count_ NonBlockingThreadPool member variable

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William Kong 2025-01-28 17:22:15 +00:00 committed by Antonio Sánchez
parent bc67025ba7
commit 5d866a7a78
1 changed files with 6 additions and 8 deletions
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14
Eigen/src/ThreadPool/NonBlockingThreadPool.h
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@ -42,7 +42,11 @@ class ThreadPoolTempl : public Eigen::ThreadPoolInterface {
: env_(env),
num_threads_(num_threads),
allow_spinning_(allow_spinning),
spin_count_(0),
spin_count_(
// TODO(dvyukov,rmlarsen): The time spent in NonEmptyQueueIndex() is proportional to num_threads_ and
// we assume that new work is scheduled at a constant rate, so we divide `kSpintCount` by number of
// threads and number of spinning threads. The constant was picked based on a fair dice roll, tune it.
allow_spinning && num_threads > 0 ? kSpinCount / kMaxSpinningThreads / num_threads : 0),
thread_data_(num_threads),
all_coprimes_(num_threads),
waiters_(num_threads),
@ -311,7 +315,7 @@ class ThreadPoolTempl : public Eigen::ThreadPoolInterface {
Environment env_;
const int num_threads_;
const bool allow_spinning_;
int spin_count_;
const int spin_count_;
MaxSizeVector<ThreadData> thread_data_;
MaxSizeVector<MaxSizeVector<unsigned>> all_coprimes_;
MaxSizeVector<EventCount::Waiter> waiters_;
@ -346,12 +350,6 @@ class ThreadPoolTempl : public Eigen::ThreadPoolInterface {
pt->pool = this;
pt->rand = GlobalThreadIdHash();
pt->thread_id = thread_id;
// TODO(dvyukov,rmlarsen): The time spent in NonEmptyQueueIndex() is
// proportional to num_threads_ and we assume that new work is scheduled
// at a constant rate, so we divide `kSpintCount` by number of threads
// and number of spinning threads. The constant was picked based on a
// fair dice roll, tune it.
spin_count_ = allow_spinning_ && num_threads_ > 0 ? kSpinCount / kMaxSpinningThreads / num_threads_ : 0;
Task t;
while (!cancelled_.load(std::memory_order_relaxed)) {
MaybeGetTask(&t);