伯克利数据库：我在这里做错了什么？

Question

我编写了一个小程序来探索使用 C# 来使用 Berkeley DB。

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

using BerkeleyDB;

namespace bdbtest {

    class Program {

        const string dbfile = @"c:\tmp\test.db";
        const int nIndexes = 5, nRecords = 500;

        static SecondaryKeyGenDelegate MakeKeyGen(int idx) {
            return (k, v) => new DatabaseEntry(Encoding.UTF8.GetBytes(Encoding.UTF8.GetString(v.Data) + string.Format("_{0}", idx)));
        }

        static void Main(string[] args) {

            File.Delete(dbfile);

            var environment = DatabaseEnvironment.Open(null,
                new DatabaseEnvironmentConfig() {
                    Create = true,
                    Private = true,
                    UseMPool = true,
                    ErrorPrefix = "Env: ",
                    ErrorFeedback = (pfx, msg) => Console.WriteLine(pfx + msg),
                });

            var table = RecnoDatabase.Open(dbfile, "table",
                new RecnoDatabaseConfig() {
                    Env = environment,
                    Creation = CreatePolicy.IF_NEEDED,
                    ErrorPrefix = "Table: ",
                    ErrorFeedback = (pfx, msg) => Console.WriteLine(pfx + msg),
                });

            var indexes = new List<SecondaryBTreeDatabase>();
            for (int idx = 0; idx < nIndexes; ++idx)
                indexes.Add(SecondaryBTreeDatabase.Open(dbfile, string.Format("index_{0}", idx),
                    new SecondaryBTreeDatabaseConfig(table, MakeKeyGen(idx)) {
                        Env = environment,
                        Creation = CreatePolicy.IF_NEEDED,
                        Compare = (k1, k2) => string.Compare(Encoding.UTF8.GetString(k1.Data), Encoding.UTF8.GetString(k2.Data)),
                        ErrorPrefix = "Index: ",
                        ErrorFeedback = (pfx, msg) => Console.WriteLine(pfx + msg),
                    }));

            for (int rn = 0; rn < nRecords; ++rn) {
                string s = string.Format("rec{0}", rn);
                table.Append(new DatabaseEntry(Encoding.UTF8.GetBytes(s)));
                Console.WriteLine(s);
            }

            foreach (var index in indexes)
                index.Close();
            indexes.Clear();
            table.Close();
            environment.Close();
        }
    }
}

它创建一个用作表的数据库，并创建多个辅助数据库作为该表的索引。问题是崩溃并出现以下错误：

Unhandled Exception: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at BerkeleyDB.Internal.libdb_csharpPINVOKE.DB_put(HandleRef jarg1, HandleRef jarg2, HandleRef jarg3, HandleRef jarg4, UInt32 jarg5)
   at BerkeleyDB.Internal.DB.put(DB_TXN txn, DatabaseEntry key, DatabaseEntry data, UInt32 flags)
   at BerkeleyDB.Database.Put(DatabaseEntry key, DatabaseEntry data, Transaction txn, UInt32 flags)
   at BerkeleyDB.RecnoDatabase.Append(DatabaseEntry data, Transaction txn)
   at BerkeleyDB.RecnoDatabase.Append(DatabaseEntry data)
   at bdbtest.Program.Main(String[] args) in C:\Users\fgb\Documents\Visual Studio 2008\Projects\bdbtest\bdbtest\Program.cs:line 53

将一定数量的记录写入表后，它总是崩溃。此外，当我增加 nIndexes 的值时，崩溃之前写入的记录数会下降。如果值足够低（例如 nIndexes = 5、nRecords = 50），程序将顺利完成。这让我觉得我正在耗尽有限的资源，但我就是看不出问题出在哪里。