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[6.0] Fix connection pool concurrency issue (#3632) #3654

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Merged
Parent: [release/6.0] Use NET9 sdk in signing pipeline
merged 5 commits into from
Oct 7, 2025
Merged

[6.0] Fix connection pool concurrency issue (#3632) #3654

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18a0778
Fix connection pool concurrency issue (#3632)
cheenamalhotra Oct 3, 2025
b4a20b8
Fix object id
cheenamalhotra Oct 3, 2025
74d924b
Update src/Microsoft.Data.SqlClient/tests/ManualTests/Microsoft.Data.…
cheenamalhotra Oct 3, 2025
93d7455
Revert semaphore holder
cheenamalhotra Oct 6, 2025
34ebd97
Code improvements
cheenamalhotra Oct 6, 2025
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59 changes: 27 additions & 32 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/ProviderBase/DbConnectionPool.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -362,7 +362,7 @@ internal WaitHandle[] GetHandles(bool withCreate)
}
}

private const int MAX_Q_SIZE = (int)0x00100000;
private const int MAX_Q_SIZE = 0x00100000;

// The order of these is important; we want the WaitAny call to be signaled
// for a free object before a creation signal. Only the index first signaled
Expand Down Expand Up @@ -1412,29 +1412,36 @@ private bool TryGetConnection(DbConnection owningObject, uint waitForMultipleObj
DestroyObject(obj);
obj = null; // Setting to null in case creating a new object fails

bool obtained = false;
if (onlyOneCheckConnection)
{
if (_waitHandles.CreationSemaphore.WaitOne(unchecked((int)waitForMultipleObjectsTimeout)))
{
#if NETFRAMEWORK
RuntimeHelpers.PrepareConstrainedRegions();
RuntimeHelpers.PrepareConstrainedRegions();
#endif
try
try
{
obtained = _waitHandles.CreationSemaphore.WaitOne((int)waitForMultipleObjectsTimeout);
if (obtained)
{
SqlClientEventSource.Log.TryPoolerTraceEvent("<prov.DbConnectionPool.GetConnection|RES|CPOOL> {0}, Creating new connection.", ObjectID);
obj = UserCreateRequest(owningObject, userOptions);
}
finally
else
{
_waitHandles.CreationSemaphore.Release(1);
// Timeout waiting for creation semaphore - return null
SqlClientEventSource.Log.TryPoolerTraceEvent("<prov.DbConnectionPool.GetConnection|RES|CPOOL> {0}, Wait timed out.", ObjectID);
connection = null;
return false;
}
}
else
finally
{
// Timeout waiting for creation semaphore - return null
SqlClientEventSource.Log.TryPoolerTraceEvent("<prov.DbConnectionPool.GetConnection|RES|CPOOL> {0}, Wait timed out.", ObjectID);
connection = null;
return false;
if (obtained)
{
// Ensure that we release this waiter, regardless
// of any exceptions that may be thrown.
_waitHandles.CreationSemaphore.Release(1);
}
}
}
}
Expand Down Expand Up @@ -1657,25 +1664,17 @@ private void PoolCreateRequest(object state)
{
return;
}
int waitResult = BOGUS_HANDLE;

bool obtained = false;
#if NETFRAMEWORK
RuntimeHelpers.PrepareConstrainedRegions();
#endif
try
{
// Obtain creation mutex so we're the only one creating objects
// and we must have the wait result
#if NETFRAMEWORK
RuntimeHelpers.PrepareConstrainedRegions();
#endif
try
{ }
finally
{
waitResult = WaitHandle.WaitAny(_waitHandles.GetHandles(withCreate: true), CreationTimeout);
}
if (CREATION_HANDLE == waitResult)
obtained = _waitHandles.CreationSemaphore.WaitOne(CreationTimeout);

if (obtained)
{
DbConnectionInternal newObj;

Expand Down Expand Up @@ -1710,17 +1709,12 @@ private void PoolCreateRequest(object state)
}
}
}
else if (WaitHandle.WaitTimeout == waitResult)
else
{
// do not wait forever and potential block this worker thread
// instead wait for a period of time and just requeue to try again
QueuePoolCreateRequest();
}
else
{
// trace waitResult and ignore the failure
SqlClientEventSource.Log.TryPoolerTraceEvent("<prov.DbConnectionPool.PoolCreateRequest|RES|CPOOL> {0}, PoolCreateRequest called WaitForSingleObject failed {1}", ObjectID, waitResult);
}
}
catch (Exception e)
{
Expand All @@ -1736,9 +1730,10 @@ private void PoolCreateRequest(object state)
}
finally
{
if (CREATION_HANDLE == waitResult)
if (obtained)
{
// reuse waitResult and ignore its value
// Ensure that we release this waiter, regardless
// of any exceptions that may be thrown.
_waitHandles.CreationSemaphore.Release(1);
}
}
Expand Down
3 changes: 3 additions & 0 deletions ...soft.Data.SqlClient/tests/ManualTests/Microsoft.Data.SqlClient.ManualTesting.Tests.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -253,6 +253,9 @@
<None Include="SQL\ParameterTest\SqlParameterTest_ReleaseMode.bsl" />
<None Include="SQL\ParameterTest\SqlParameterTest_ReleaseMode_Azure.bsl" />
</ItemGroup>
<ItemGroup Condition="'$(TestSet)' == '' OR '$(TestSet)' == '3'">
<Compile Include="SQL\ConnectionPoolTest\ConnectionPoolStressTest.cs" />
</ItemGroup>
<ItemGroup Condition="'$(TargetGroup)'=='netcoreapp' AND ('$(TestSet)' == '' OR '$(TestSet)' == '3')">
<Compile Include="TracingTests\EventCounterTest.cs" />
<Compile Include="TracingTests\DiagnosticTest.cs" />
Expand Down
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