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Fix Http2 deadlock #99889

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merged 3 commits into from
Mar 21, 2024
Merged

Fix Http2 deadlock #99889

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3b48cbc
Fix Http2 deadlock
MihaZupan Mar 18, 2024
7cd5edc
Merge branch 'main' into http-h2deadlock
MihaZupan Mar 19, 2024
36ecb19
Merge branch 'main' into http-h2deadlock
MihaZupan Mar 21, 2024
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23 changes: 19 additions & 4 deletions src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -257,6 +257,7 @@ private void Shutdown()
if (NetEventSource.Log.IsEnabled()) Trace($"{nameof(_shutdown)}={_shutdown}, {nameof(_abortException)}={_abortException}");

Debug.Assert(Monitor.IsEntered(SyncObject));
Debug.Assert(!_pool.HasSyncObjLock);

if (!_shutdown)
{
Expand All @@ -276,6 +277,8 @@ private void Shutdown()

public bool TryReserveStream()
{
Debug.Assert(!_pool.HasSyncObjLock);

lock (SyncObject)
{
if (_shutdown)
Expand All @@ -302,6 +305,8 @@ public bool TryReserveStream()
// Otherwise, will be called when the request is complete and stream is closed.
public void ReleaseStream()
{
Debug.Assert(!_pool.HasSyncObjLock);

lock (SyncObject)
{
if (NetEventSource.Log.IsEnabled()) Trace($"{nameof(_streamsInUse)}={_streamsInUse}");
Expand Down Expand Up @@ -333,6 +338,8 @@ public void ReleaseStream()
// Returns false to indicate that the connection is shutting down and cannot be used anymore
public Task<bool> WaitForAvailableStreamsAsync()
{
Debug.Assert(!_pool.HasSyncObjLock);

lock (SyncObject)
{
Debug.Assert(_availableStreamsWaiter is null, "As used currently, shouldn't already have a waiter");
Expand Down Expand Up @@ -730,6 +737,7 @@ private void ProcessAltSvcFrame(FrameHeader frameHeader)
{
if (NetEventSource.Log.IsEnabled()) Trace($"{frameHeader}");
Debug.Assert(frameHeader.Type == FrameType.AltSvc);
Debug.Assert(!Monitor.IsEntered(SyncObject));

ReadOnlySpan<byte> span = _incomingBuffer.ActiveSpan.Slice(0, frameHeader.PayloadLength);

Expand Down Expand Up @@ -1304,6 +1312,8 @@ private Task SendRstStreamAsync(int streamId, Http2ProtocolErrorCode errorCode)

internal void HeartBeat()
{
Debug.Assert(!_pool.HasSyncObjLock);

if (_shutdown)
return;

Expand Down Expand Up @@ -1810,10 +1820,14 @@ private bool ForceSendConnectionWindowUpdate()

public override long GetIdleTicks(long nowTicks)
{
lock (SyncObject)
{
return _streamsInUse == 0 ? base.GetIdleTicks(nowTicks) : 0;
}
// The pool is holding the lock as part of its scavenging logic.
// We must not lock on Http2Connection.SyncObj here as that could lead to lock ordering problems.
Debug.Assert(_pool.HasSyncObjLock);

// There is a race condition here where the connection pool may see this connection as idle right before
// we start processing a new request and start its disposal. This is okay as we will either
// return false from TryReserveStream, or process pending requests before tearing down the transport.
return _streamsInUse == 0 ? base.GetIdleTicks(nowTicks) : 0;
}

/// <summary>Abort all streams and cause further processing to fail.</summary>
Expand Down Expand Up @@ -2002,6 +2016,7 @@ private static TaskCompletionSourceWithCancellation<bool> CreateSuccessfullyComp
public async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, bool async, CancellationToken cancellationToken)
{
Debug.Assert(async);
Debug.Assert(!_pool.HasSyncObjLock);
if (NetEventSource.Log.IsEnabled()) Trace($"Sending request: {request}");

try
Expand Down
6 changes: 5 additions & 1 deletion src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -406,7 +406,7 @@ private object SyncObj
}
}

private bool HasSyncObjLock => Monitor.IsEntered(_availableHttp11Connections);
public bool HasSyncObjLock => Monitor.IsEntered(_availableHttp11Connections);

// Overview of connection management (mostly HTTP version independent):
//
Expand Down Expand Up @@ -459,6 +459,8 @@ private static void ThrowGetVersionException(HttpRequestMessage request, int des

private bool CheckExpirationOnGet(HttpConnectionBase connection)
{
Debug.Assert(!HasSyncObjLock);

TimeSpan pooledConnectionLifetime = _poolManager.Settings._pooledConnectionLifetime;
if (pooledConnectionLifetime != Timeout.InfiniteTimeSpan)
{
Expand Down Expand Up @@ -1999,6 +2001,7 @@ private void ReturnHttp2Connection(Http2Connection connection, bool isNewConnect
{
if (NetEventSource.Log.IsEnabled()) connection.Trace($"{nameof(isNewConnection)}={isNewConnection}");

Debug.Assert(!HasSyncObjLock);
Debug.Assert(isNewConnection || initialRequestWaiter is null, "Shouldn't have a request unless the connection is new");

if (!isNewConnection && CheckExpirationOnReturn(connection))
Expand Down Expand Up @@ -2402,6 +2405,7 @@ internal void HeartBeat()
localHttp2Connections = _availableHttp2Connections?.ToArray();
}

// Avoid calling HeartBeat under the lock, as it may call back into HttpConnectionPool.InvalidateHttp2Connection.
if (localHttp2Connections is not null)
{
foreach (Http2Connection http2Connection in localHttp2Connections)
Expand Down