大量のガベージを生成する巨大なプログラムがあります。これにより、パフォーマンスが低下し、毎秒数千のソフト ページ フォールトが生成され、待ち時間が短縮され、スループットが低下します。
主な原因の 1 つはSystem.Collections.Generic.Dictionaryであるため、たとえば 10,000 エントリを事前に割り当てて、これらのエントリをその場で再利用できるバージョンに置き換えたいと考えています。
Dictionaryエントリの事前割り当てを許可し、実行時にガベージを生成しない既存の実装はありますか?
ガベージ フリー ディクショナリは、全体的な GC にそれほど影響を与えなかったため、最終的には使用しないことにしました。
記録のために、ガベージフリー辞書の実装を次に示します。メモリが不足していますが、うまく機能します。
使用するには、潜在的な整数キーに十分なスロットを備えた新しい辞書をインスタンス化します。たとえば、プライマリ整数キーの範囲が 0 ～ 50,000 の場合、インスタンス化するときに 50,000 を渡す必要があります。
MyIntegerKeyDictionary = new MyIntegerKeyDictionary<int, MyClass>(50000);
キーが 200,000 から 250,000 の範囲になる可能性がある場合、50,000 の潜在的なキーでインスタンス化すると、200,000 から 250,000 の範囲になるように (最初に検出されたキーに基づいて) キーが自動的に「リベース」されます。
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using MyLogType;
namespace MyHelper
{
/// <summary>
/// NOTE: Non thread safe, only run this individually.
/// </summary>
/// <typeparam name="T">Type of item we are adding to the dictionary.</typeparam>
public class MyIntegerKeyDictionary<T> where T : class
{
/// <summary>
/// Array in which we store the entries.
/// </summary>
volatile private T[] ArrayToUse;
/// <summary>
/// Allows us to check the maximum size, just in case.
/// </summary>
private readonly int SizeInternal;
/// <summary>
/// Keeps track of the current number of items in the dictionary.
/// </summary>
public int Count = 0;
/// <summary>
/// Base number. For numbers that start with a huge base, this allows the index to work without allocating megabytes of memory.
/// </summary>
private int BaseNumberToAdd { get; set; }
/// <summary>
/// Constructor.
/// </summary>
/// <param name="Size">Size of the dictionary.</param>
public MyIntegerKeyDictionary(int Size)
{
// Create the array to hold n number of items.
ArrayToUse = new T[Size];
// We must touch all of these entries, to force page faults now (rather than later).
for (int i = 0; i < ArrayToUse.Length; i++)
{
ArrayToUse[i] = null;
}
BaseNumberToAdd = int.MinValue;
this.SizeInternal = Size;
}
/// <summary>
/// Add an item.
/// </summary>
/// <param name="Key">Key.</param>
/// <param name="Value">Value.</param>
/// <returns>True if the item was added, false if not.</returns>
public bool TryAdd(int Key, T Value)
{
if (BaseNumberToAdd == int.MinValue)
{
BaseNumberToAdd = Key;
//Console.Write(string.Format("{0}Message W20120907-3751. TryAdd. Adding first item {1}.\n",
//MyLog.NPrefix(), Key));
}
Key = Key - BaseNumberToAdd;
if (Key < 0)
{
Console.Write(string.Format("{0}Warning W20120907-3750. TryAdd. Attempted to add a key with index {1} which is < 0.\n",
MyLog.NPrefix(), Key));
return false;
}
if (Key >= this.SizeInternal)
{
Console.Write(string.Format("{0}Warning W20120907-3756. TryAdd. Attempted to add a key with index {1} which is > max {2}\n",
MyLog.NPrefix(), Key, this.SizeInternal));
return false;
}
if (ArrayToUse[Key] == null)
{
Interlocked.Increment(ref Count);
}
ArrayToUse[Key] = Value;
return true;
}
/// <summary>
/// Remove an item from the dictionary.
/// </summary>
/// <param name="Key">Key that we want to remove.</param>
/// <returns>True if the item could be removed, false if not.</returns>
public bool TryRemove(int Key)
{
if (BaseNumberToAdd == int.MinValue)
{
Console.Write(string.Format("{0}Warning W20120907-8756. TryRemove. Attempted to remove an item without any items in the dictionary yet {1}.\n",
MyLog.NPrefix(), Key));
return false;
}
Key = Key - BaseNumberToAdd;
if (Key < 0)
{
Console.Write(string.Format("{0}Warning W20120907-9756. TryRemove. Attempted to remove a key with index {1} which is < 0.\n",
MyLog.NPrefix(), Key));
return false;
}
if (Key >= this.SizeInternal)
{
Console.Write(string.Format("{0}Warning W20120907-6756. TryRemove. Attempted to remove a key with index {1} which is > max {2}\n",
MyLog.NPrefix(), Key, this.SizeInternal));
return false;
}
if (ArrayToUse[Key] != null)
{
Interlocked.Decrement(ref Count);
}
ArrayToUse[Key] = null;
return true;
}
/// <summary>
/// Indexer.
/// </summary>
/// <param name="key">Key.</param>
/// <returns>Value.</returns>
public T this[int key]
{
get
{
T valueToReturn;
TryGetValue(key, out valueToReturn);
return valueToReturn;
}
}
/// <summary>
/// Attempt to get the value.
/// </summary>
/// <param name="Key">Key.</param>
/// <param name="Value">Value.</param>
/// <returns>True if the value exists, false if not.</returns>
public bool TryGetValue(int Key, out T Value)
{
Value = null;
if (BaseNumberToAdd == int.MinValue)
{
Console.Write(string.Format("{0}Warning W20120907-8756. TryGetValue. Attempted to retrieve an item without any items in the dictionary yet {1}.\n",
MyLog.NPrefix(), Key));
return false;
}
Key = Key - BaseNumberToAdd;
if (ArrayToUse[Key] == null)
{
return false;
}
Value = ArrayToUse[Key];
return true;
}
/// <summary>
/// Checks to see if the key exists.
/// </summary>
/// <param name="Key">Key index.</param>
/// <returns>True if the item exists, false if not.</returns>
public bool ContainsKey(int Key)
{
if (Key == 0)
{
Console.Write(string.Format("{0}Warning W20120907-1914. ContainsKey. Have not rebased yet. Ignoring query for ContainsKey(0).\n",
MyLog.NPrefix()));
return false;
}
if (BaseNumberToAdd == int.MinValue)
{
Console.Write(string.Format("{0}Warning W20120907-8756. ContainsKey. Attempted to check if Key {1} exists, however BaseNumber is not set yet.\n",
"", Key));
return false;
}
Key = Key - BaseNumberToAdd;
if (Key < 0)
{
Console.Write(string.Format("{0}Warning W20120907-8756. ContainsKey. Key = {1} which is < 0.\n",
"", Key));
return false;
}
if (Key >= this.SizeInternal)
{
MyLogAsync.LogWarning(string.Format("{0}Warning W20120907-5756. ContainsKey. Key({1}) >= this.SizeInternal ({2}).\n",
MyLog.NPrefix(), Key, this.SizeInternal));
return false;
}
if (ArrayToUse[Key] == null)
{
return false;
}
return true;
}
/*
private bool CheckKeyBounds(int Key, string description)
{
if (Key < 0)
{
MyLogAsync.LogWarning(string.Format("{0}Warning W20120907-8756. {1}. Attempted to add a key with index {2} which is < 0.\n",
MyLog.NPrefix(), description, Key));
}
if (Key >= this.SizeInternal)
{
MyLogAsync.LogWarning(string.Format("{0}Warning W20120907-5756. {1}. Attempted to add a key with index {2} which is > max {3}\n",
MyLog.NPrefix(), description, Key, this.SizeInternal));
return false;
}
}
*/
}
}