Skip to content

[release/7.0] Fixing memory ordering issue in ConcurrentQueue #78178

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 14, 2022
Merged

[release/7.0] Fixing memory ordering issue in ConcurrentQueue #78178

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 4 additions & 6 deletions src/libraries/System.Private.CoreLib/src/System/Collections/Concurrent/ConcurrentQueue.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -528,13 +528,11 @@ private static T GetItemWhenAvailable(ConcurrentQueueSegment<T> segment, int i)

// If the expected sequence number is not yet written, we're still waiting for
// an enqueuer to finish storing it. Spin until it's there.
if ((segment._slots[i].SequenceNumber & segment._slotsMask) != expectedSequenceNumberAndMask)
SpinWait spinner = default;
// Must read SequenceNumber before reading Item, thus Volatile.Read
while ((Volatile.Read(ref segment._slots[i].SequenceNumber) & segment._slotsMask) != expectedSequenceNumberAndMask)
{
SpinWait spinner = default;
while ((Volatile.Read(ref segment._slots[i].SequenceNumber) & segment._slotsMask) != expectedSequenceNumberAndMask)
{
spinner.SpinOnce();
}
spinner.SpinOnce();
}

// Return the value from the slot.
Expand Down