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[backend/queue] Fix AsyncAutoResetEvent handling, fix stalled queue workers causing no new workers to be spawned

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This commit is contained in:
Laura Hausmann 2024-06-16 16:53:27 +02:00
parent 364d0c54a0
commit 7ed39d0c47
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GPG key ID: D044E84C5BE01605
3 changed files with 135 additions and 7 deletions
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35
Iceshrimp.Backend/Core/Helpers/EventHelpers.cs
View file

@ -2,7 +2,9 @@ namespace Iceshrimp.Backend.Core.Helpers;
public sealed class AsyncAutoResetEvent(bool signaled = false)
{
private readonly List<TaskCompletionSource<bool>> _taskCompletionSources = [];
private readonly List<TaskCompletionSource<bool>> _taskCompletionSources = [];
private readonly List<TaskCompletionSource<bool>> _noResetTaskCompletionSources = [];
public bool Signaled => signaled;
public Task<bool> WaitAsync(CancellationToken cancellationToken = default)
{
@ -21,19 +23,39 @@ public sealed class AsyncAutoResetEvent(bool signaled = false)
}
}
public Task<bool> WaitWithoutResetAsync(CancellationToken cancellationToken = default)
{
lock (_taskCompletionSources)
{
if (signaled)
return Task.FromResult(true);
var tcs = new TaskCompletionSource<bool>();
cancellationToken.Register(Callback, (this, tcs));
_noResetTaskCompletionSources.Add(tcs);
return tcs.Task;
}
}
public void Set()
{
lock (_taskCompletionSources)
{
if (_taskCompletionSources.Count > 0)
signaled = true;
foreach (var tcs in _noResetTaskCompletionSources.ToList())
{
var tcs = _taskCompletionSources[0];
_taskCompletionSources.RemoveAt(0);
_noResetTaskCompletionSources.Remove(tcs);
tcs.TrySetResult(true);
return;
}
signaled = true;
if (_taskCompletionSources.Count == 0) return;
signaled = false;
foreach (var tcs in _taskCompletionSources.ToList())
{
_taskCompletionSources.Remove(tcs);
tcs.TrySetResult(true);
}
}
}
@ -45,6 +67,7 @@ public sealed class AsyncAutoResetEvent(bool signaled = false)
if (tcs.Task.IsCompleted) return;
tcs.TrySetCanceled();
ev._taskCompletionSources.Remove(tcs);
ev._noResetTaskCompletionSources.Remove(tcs);
}
}
}

14
Iceshrimp.Backend/Core/Services/QueueService.cs
View file

@ -259,8 +259,20 @@ public class PostgresJobQueue<T>(
continue;
}
// ReSharper disable MethodSupportsCancellation
var queuedChannelCts = new CancellationTokenSource();
if (actualParallelism < parallelism)
{
_ = _queuedChannel.WaitWithoutResetAsync()
.ContinueWith(_ => { queuedChannelCts.Cancel(); })
.SafeWaitAsync(queueToken);
}
// ReSharper restore MethodSupportsCancellation
var tasks = TaskExtensions.QueueMany(() => AttemptProcessJobAsync(token), actualParallelism);
await Task.WhenAny(tasks).SafeWaitAsync(queueToken, () => Task.WhenAll(tasks).WaitAsync(token));
await Task.WhenAny(tasks)
.SafeWaitAsync(queuedChannelCts.Token)
.SafeWaitAsync(queueToken, () => Task.WhenAll(tasks).WaitAsync(token));
}
catch (Exception e)
{

93
Iceshrimp.Tests/Concurrency/EventTests.cs Normal file
View file

@ -0,0 +1,93 @@
using Iceshrimp.Backend.Core.Helpers;
namespace Iceshrimp.Tests.Concurrency;
[TestClass]
public class EventTests
{
[TestMethod]
public async Task TestAsyncAutoResetEvent()
{
var autoResetEvent = new AsyncAutoResetEvent();
var pre = DateTime.Now;
var task = autoResetEvent.WaitAsync();
_ = Task.Run(async () =>
{
await Task.Delay(50);
autoResetEvent.Set();
});
await task;
(DateTime.Now - pre).Should().BeGreaterThan(TimeSpan.FromMilliseconds(50));
autoResetEvent.Signaled.Should().BeFalse();
}
[TestMethod]
public async Task TestAsyncAutoResetEventWithoutReset()
{
var autoResetEvent = new AsyncAutoResetEvent();
var pre = DateTime.Now;
var task = autoResetEvent.WaitWithoutResetAsync();
_ = Task.Run(async () =>
{
await Task.Delay(50);
autoResetEvent.Set();
});
await task;
(DateTime.Now - pre).Should().BeGreaterThan(TimeSpan.FromMilliseconds(50));
autoResetEvent.Signaled.Should().BeTrue();
}
[TestMethod]
public async Task TestAsyncAutoResetEventMulti()
{
var autoResetEvent = new AsyncAutoResetEvent();
var pre = DateTime.Now;
Task[] tasks = [autoResetEvent.WaitAsync(), autoResetEvent.WaitAsync()];
_ = Task.Run(async () =>
{
await Task.Delay(50);
autoResetEvent.Set();
});
await Task.WhenAll(tasks);
(DateTime.Now - pre).Should().BeGreaterThan(TimeSpan.FromMilliseconds(50));
autoResetEvent.Signaled.Should().BeFalse();
}
[TestMethod]
public async Task TestAsyncAutoResetEventWithoutResetMulti()
{
var autoResetEvent = new AsyncAutoResetEvent();
var pre = DateTime.Now;
Task[] tasks = [autoResetEvent.WaitWithoutResetAsync(), autoResetEvent.WaitWithoutResetAsync()];
_ = Task.Run(async () =>
{
await Task.Delay(50);
autoResetEvent.Set();
});
await Task.WhenAll(tasks);
(DateTime.Now - pre).Should().BeGreaterThan(TimeSpan.FromMilliseconds(50));
autoResetEvent.Signaled.Should().BeTrue();
}
[TestMethod]
public async Task TestAsyncAutoResetEventPre()
{
var autoResetEvent = new AsyncAutoResetEvent();
autoResetEvent.Set();
await autoResetEvent.WaitAsync();
autoResetEvent.Signaled.Should().BeFalse();
await Assert.ThrowsExceptionAsync<TimeoutException>(() => autoResetEvent.WaitAsync()
.WaitAsync(TimeSpan.FromMilliseconds(50)));
}
[TestMethod]
public async Task TestAsyncAutoResetEventPreMulti()
{
var autoResetEvent = new AsyncAutoResetEvent();
autoResetEvent.Set();
await autoResetEvent.WaitWithoutResetAsync();
autoResetEvent.Signaled.Should().BeTrue();
await autoResetEvent.WaitWithoutResetAsync();
autoResetEvent.Signaled.Should().BeTrue();
}
}