ODP.NET OracleCommand类具有CommandTimeout属性，可用于强制执行命令的超时。此属性似乎适用于CommandText是SQL语句的情况。示例代码用于说明此属性的实际应用。在代码的初始版本中，CommandTimeout设置为零 - 告诉ODP.NET不要强制执行超时。
using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Text;
using Oracle.DataAccess.Client;
namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
using (OracleConnection con = new OracleConnection("User ID=xxxx; Password=xxxx; Data Source=xxxx;"))
using (OracleCommand cmd = new OracleCommand())
{
con.Open();
cmd.Connection = con;
Console.WriteLine("Executing Query...");
try
{
cmd.CommandTimeout = 0;
// Data set SQL:
cmd.CommandText = "<some long running SQL statement>";
cmd.CommandType = System.Data.CommandType.Text;
Stopwatch watch1 = Stopwatch.StartNew();
OracleDataReader reader = cmd.ExecuteReader();
watch1.Stop();
Console.WriteLine("Query complete. Execution time: {0} ms", watch1.ElapsedMilliseconds);
int counter = 0;
Stopwatch watch2 = Stopwatch.StartNew();
if (reader.Read()) counter++;
watch2.Stop();
Console.WriteLine("First record read: {0} ms", watch2.ElapsedMilliseconds);
Stopwatch watch3 = Stopwatch.StartNew();
while (reader.Read())
{
counter++;
}
watch3.Stop();
Console.WriteLine("Records 2..n read: {0} ms", watch3.ElapsedMilliseconds);
Console.WriteLine("Records read: {0}", counter);
}
catch (OracleException ex)
{
Console.WriteLine("Exception was thrown: {0}", ex.Message);
}
Console.WriteLine("Press any key to continue...");
Console.Read();
}
}
}
}
以上代码的示例输出如下所示：
Executing Query...
Query complete. Execution time: 8372 ms
First record read: 3 ms
Records 2..n read: 1222 ms
Records read: 20564
Press any key to continue...
如果我将CommandTimeout更改为3 ...
cmd.CommandTimeout = 3;
...然后运行相同的代码会产生以下输出：
Executing Query...
Exception was thrown: ORA-01013: user requested cancel of current operation
Press any key to continue...
调用返回引用游标的存储过程是另一回事。考虑下面的测试过程（纯粹用于测试目的）：
PROCEDURE PROC_A(i_sql VARCHAR2, o_cur1 OUT SYS_REFCURSOR)
is
begin
open o_cur1
for
i_sql;
END PROC_A;
下面的示例代码可用于调用存储过程。请注意，它将CommandTimeout设置为值3。
using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Text;
using Oracle.DataAccess.Client;
namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
using (OracleConnection con = new OracleConnection("User ID=xxxx; Password=xxxx; Data Source=xxxx;"))
using (OracleCommand cmd = new OracleCommand())
{
con.Open();
cmd.Connection = con;
Console.WriteLine("Executing Query...");
try
{
cmd.CommandTimeout = 3;
string sql = "<some long running sql>";
cmd.CommandText = "PROC_A";
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.Parameters.Add(new OracleParameter("i_sql", OracleDbType.Varchar2) { Direction = ParameterDirection.Input, Value = sql });
cmd.Parameters.Add(new OracleParameter("o_cur1", OracleDbType.RefCursor) { Direction = ParameterDirection.Output });
Stopwatch watch1 = Stopwatch.StartNew();
OracleDataReader reader = cmd.ExecuteReader();
watch1.Stop();
Console.WriteLine("Query complete. Execution time: {0} ms", watch1.ElapsedMilliseconds);
int counter = 0;
Stopwatch watch2 = Stopwatch.StartNew();
if (reader.Read()) counter++;
watch2.Stop();
Console.WriteLine("First record read: {0} ms", watch2.ElapsedMilliseconds);
Stopwatch watch3 = Stopwatch.StartNew();
while (reader.Read())
{
counter++;
}
watch3.Stop();
Console.WriteLine("Records 2..n read: {0} ms", watch3.ElapsedMilliseconds);
Console.WriteLine("Records read: {0}", counter);
}
catch (OracleException ex)
{
Console.WriteLine("Exception was thrown: {0}", ex.Message);
}
Console.WriteLine("Press any key to continue...");
Console.Read();
}
}
}
}
上面代码的示例输出如下所示：
Executing Query...
Query complete. Execution time: 34 ms
First record read: 8521 ms
Records 2..n read: 1014 ms
Records read: 20564
Press any key to continue...
请注意，执行时间非常快（34毫秒），并且未引发超时异常。我们在这里看到的性能是因为在第一次调用OracleDataReader.Read方法之前，不会执行ref游标的SQL语句。当第一次Read（）调用从refcursor读取第一个记录时，将导致长时间运行的查询中的性能命中。
我所说明的行为意味着OracleCommand.CommandTimeout属性不能用于取消与ref游标关联的长时间运行的查询。我不知道ODP.NET中的任何属性可以用来限制在这种情况下引用游标SQL的执行时间。任何人都有一些关于如何在一定时间后将长时间运行的引用游标SQL语句的执行短路的建议？
答案 0 :(得分：4)
这是我最终选择的解决方案。它只是OracleDataReader类的扩展方法。此方法具有超时值和回调函数作为参数。回调函数通常（如果不总是）是OracleCommand.Cancel。
namespace ConsoleApplication1
{
public static class OracleDataReaderExtensions
{
public static bool Read(this OracleDataReader reader, int timeout, Action cancellationAction)
{
Task<bool> task = Task<bool>.Factory.StartNew(() =>
{
try
{
return reader.Read();
}
catch (OracleException ex)
{
// When cancellationAction is called below, it will trigger
// an ORA-01013 error in the Read call that is still executing.
// This exception can be ignored as we're handling the situation
// by throwing a TimeoutException.
if (ex.Number == 1013)
{
return false;
}
else
{
throw;
}
}
});
try
{
if (!task.Wait(timeout))
{
// call the cancellation callback function (i.e. OracleCommand.Cancel())
cancellationAction();
// throw an exception to notify calling code that a timeout has occurred
throw new TimeoutException("The OracleDataReader.Read operation has timed-out.");
}
return task.Result;
}
catch (AggregateException ae)
{
throw ae.Flatten();
}
}
}
}
以下是如何使用它的示例。
namespace ConsoleApplication1
{
class Program
{
static string constring = "User ID=xxxx; Password=xxxx; Data Source=xxxx;";
static void Main(string[] args)
{
using (OracleConnection con = new OracleConnection(constring))
using (OracleCommand cmd = new OracleCommand())
{
cmd.Connection = con;
con.Open();
Console.WriteLine("Executing Query...");
string sql = "<some long running sql>";
cmd.CommandText = "PROC_A";
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.Parameters.Add(new OracleParameter("i_sql", OracleDbType.Varchar2) { Direction = ParameterDirection.Input, Value = sql });
cmd.Parameters.Add(new OracleParameter("o_cur1", OracleDbType.RefCursor) { Direction = ParameterDirection.Output });
try
{
// execute command and get reader for ref cursor
OracleDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
// read first record; this is where the ref cursor SQL gets evaluated
Console.WriteLine("Reading first record...");
if (reader.Read(3000, cmd.Cancel)) { }
// read remaining records
Console.WriteLine("Reading records 2 to N...");
while (reader.Read(3000, cmd.Cancel)) { }
}
catch (TimeoutException ex)
{
Console.WriteLine("Exception: {0}", ex.Message);
}
Console.WriteLine("Press any key to continue...");
Console.Read();
}
}
}
}
这是输出的一个例子。
Executing Query...
Reading first record...
Exception: The OracleDataReader.Read operation has timed-out.
Press any key to continue...
答案 1 :(得分：1)
看来你不是第一个问： https://forums.oracle.com/forums/thread.jspa?threadID=2125208
您可以在循环中通过reader.Read（）监视已用时间并退出循环。这很简单，但当然只有在可能长时间运行的Read调用结束后才能退出。
你最好的选择可能是在一个单独的线程上执行一个循环，监视它，然后在原始线程上调用cmd.Cancel：
[Test]
public void TimeBasicSql()
{
using (OracleConnection con = new OracleConnection("User ID=id; Password=pass; Data Source=db;"))
using (OracleCommand cmd = new OracleCommand())
{
con.Open();
cmd.Connection = con;
Console.WriteLine("Executing Query...");
try
{
cmd.CommandTimeout = 1;
String sql = "begin open :o_cur1 for select count(*) from all_objects, all_objects; end;";
cmd.CommandText = sql;
cmd.Parameters.Add(new OracleParameter("o_cur1", OracleDbType.RefCursor) { Direction = ParameterDirection.Output });
var task = System.Threading.Tasks.Task.Factory.StartNew(() =>
{
try
{
Stopwatch watch1 = Stopwatch.StartNew();
OracleDataReader reader = cmd.ExecuteReader();
watch1.Stop();
Console.WriteLine("Query complete. Execution time: {0} ms", watch1.ElapsedMilliseconds);
int counter = 0;
Stopwatch watch2 = Stopwatch.StartNew();
if (reader.Read()) counter++;
watch2.Stop();
Console.WriteLine("First record read: {0} ms", watch2.ElapsedMilliseconds);
Stopwatch watch3 = Stopwatch.StartNew();
while (reader.Read())
{
counter++;
}
watch3.Stop();
Console.WriteLine("Records 2..n read: {0} ms", watch3.ElapsedMilliseconds);
Console.WriteLine("Records read: {0}", counter);
}
catch (OracleException ex)
{
Console.WriteLine("Exception was thrown: {0}", ex);
}
});
if (!task.Wait(cmd.CommandTimeout * 1000))
{
Console.WriteLine("Timeout exceeded. Cancelling...");
cmd.Cancel();
}
}
catch (OracleException ex)
{
Console.WriteLine("Exception was thrown: {0}", ex);
}
}
值得注意的是ORA-01013异常是在工作线程上引发的，而不是在调用OracleCommand.Cancel的线程上引发的。