非同期接続を使用するかなり小さなC＃プログラムでこの問題を再現できますが、100％の理由がわかりません。他の人が試してみたい場合の私の再現プログラムは次のとおりです。これを実現するには、完全に整列する必要のある一連のことがあると思います。
- 接続プーリングが有効
- 接続プールで偽装を使用し、接続プールでその偽装コンテキストを元に戻すことを禁止する
void Main()
{
var impersonateMyself = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
var testCommand = "SELECT TOP 1 * FROM sys.objects";
var calls = Enumerable.Repeat(
$@"{testCommand};",
10
);
var impersonatedCalls = Enumerable.Repeat(
$@"EXECUTE AS LOGIN = '{impersonateMyself} WITH NO REVERT'; {testCommand}; REVERT;",
10
);
Dictionary<string, object> dict = new Dictionary<string, object>()
{
};
// Scenario 1: Impersonated Calls, With connection pooling -- will randomly fail
Parallel.ForEach(
impersonatedCalls,
c => new SqlAsync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=2;").AsyncSqlCall<List<A>>(c, CommandType.Text, handleResultAsync, dict).Dump());
Parallel.ForEach(
impersonatedCalls,
c => new SqlSync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=2;").SyncSqlCall<List<A>>(c, CommandType.Text, handleResultSync, dict).Dump());
// Scenario 2: Normal calls, with connection pooling -- should succeed every time
Parallel.ForEach(
calls,
c => new SqlAsync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=2;").AsyncSqlCall<List<A>>(c, CommandType.Text, handleResultAsync, dict).Dump());
Parallel.ForEach(
calls,
c => new SqlSync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=2;").SyncSqlCall<List<A>>(c, CommandType.Text, handleResultSync, dict).Dump());
// Scenario 3: Impersonated Calls, WITHOUT connection pooling -- should succeed every time
Parallel.ForEach(
impersonatedCalls,
c => new SqlAsync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=200;").AsyncSqlCall<List<A>>(c, CommandType.Text, handleResultAsync, dict).Dump());
Parallel.ForEach(
impersonatedCalls,
c => new SqlSync("Data Source=devsql2;Initial Catalog=Test;Integrated Security=true;Max Pool Size=200;").SyncSqlCall<List<A>>(c, CommandType.Text, handleResultSync, dict).Dump());
}
public class SqlSync
{
private readonly string _connectionString;
public int Timeout {get; set;}
public SqlSync(string connString)
{
_connectionString = connString;
Timeout = 30;
}
public T SyncSqlCall<T>(string commandText, CommandType type, Func<SqlDataReader, T> handleResult, Dictionary<string, object> parameters = null)
{
using (SqlConnection conn = new SqlConnection(_connectionString))
using (SqlCommand cmd = new SqlCommand(commandText, conn))
{
cmd.CommandTimeout = Timeout;
cmd.CommandType = CommandType.Text;
if (parameters != null)
{
foreach (KeyValuePair<string, object> kvp in parameters)
cmd.Parameters.AddWithValue(kvp.Key, kvp.Value ?? DBNull.Value);
}
conn.Open();
using (var rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
return handleResult(rdr);
}
}
}
public class SqlAsync
{
private readonly string _connectionString;
public int Timeout { get; set; }
public SqlAsync(string connString)
{
_connectionString = connString;
Timeout = 30;
}
public Task<T> AsyncSqlCall<T>(string sp, CommandType commandType, Func<SqlDataReader, Task<T>> handleResult, Dictionary<string, object> parameters = null)
{
return AsyncSqlCall<T>(sp, commandType, (reader, token) => handleResult(reader), CancellationToken.None, parameters);
}
public async Task<T> AsyncSqlCall<T>(string commandText, CommandType type, Func<SqlDataReader, CancellationToken, Task<T>> handleResult, CancellationToken cancellationToken, Dictionary<string, object> parameters = null)
{
using (SqlConnection conn = new SqlConnection(_connectionString))
using (SqlCommand cmd = new SqlCommand(commandText, conn))
{
cmd.CommandTimeout = Timeout;
cmd.CommandType = CommandType.Text;
if (parameters != null)
{
foreach (KeyValuePair<string, object> kvp in parameters)
cmd.Parameters.AddWithValue(kvp.Key, kvp.Value ?? DBNull.Value);
}
await conn.OpenAsync(cancellationToken);
// if (conn.State != ConnectionState.Open)
// await Task.Delay(TimeSpan.FromMilliseconds(10));
using (var rdr = await cmd.ExecuteReaderAsync(CommandBehavior.CloseConnection, cancellationToken))
return await handleResult(rdr, cancellationToken);
}
}
}
public class A
{
public string object_name { get; set; }
}
public static Func<SqlDataReader, Task<List<A>>> handleResultAsync = (SqlDataReader sdr) =>
{
var result = new List<A>();
while (sdr.Read())
{
result.Add(new A { object_name = sdr.GetFieldValue<string>(0) });
}
return Task.FromResult(result);
};
public static Func<SqlDataReader, List<A>> handleResultSync = (SqlDataReader sdr) =>
{
var result = new List<A>();
while (sdr.Read())
{
result.Add(new A { object_name = sdr.GetFieldValue<string>(0) });
}
return result;
};