IOCP性能优化主要是集中在每个处理接收数据和发送数据的对象锁，如果能降低锁的调用次数和提高锁的效率，对IOCP的整理效率和吞吐量都非常有帮助。有很多开发人员在优化IOCP的时候，对于如何提高锁的效率，有使用原子操作来加锁，这样做的效率比较调用Windows的锁效率，因而吞吐率也更高。我们不讨论提高锁的效率，我们这次的优化是降低锁的调用次数。
服务端优化
IOCP是异步线程通知方式，，有多个线程在调用GetQueuedCompletionStatus函数等待返回，如果有发送和接收，如果正在处理中，则会导致发送等待，这是因为我们每次处理IOCP返回，我们都对TSocketHandle进行了加锁，如下：
ClientSocket.Lock.Enter;tryif Assigned(ClientSocket.SocketHandle) thenbeginClientSocket.SocketHandle.ProcessIOComplete(IocpRecord, iWorkCount);if not ClientSocket.SocketHandle.Connected thenFreeSocketHandle(ClientSocket.SocketHandle);end;finallyClientSocket.Lock.Leave;end;因此我们优化这个锁的进入次数，则能提高整个系统的吞吐量和传输性能。服务器和客户端在发送数据时，是调用不同的函数分别发送，如服务端下发响应信息函数：procedure TBaseSocket.DoSendResult;var wLen: Word; cLen: Cardinal; utf8Buff: UTF8String;begin if not Connected then Exit; utf8Buff := AnsiToUtf8(FResponse.Text); //转为UTF8 if LenType = ltWord then beginwLen := Length(utf8Buff) + SizeOf(Cardinal); //总长度WriteWord(wLen, False); end else if LenType = ltCardinal then begincLen := Length(utf8Buff) + SizeOf(Cardinal); //总长度WriteCardinal(cLen, False); end; WriteCardinal(Length(utf8Buff), False); //下发命令长度 WriteBuffer(PUTF8String(utf8Buff)^, Length(utf8Buff)); //命令内容end;这里调了多次Write函数，每次Write函数最终都会调用函数WriteBuffer，每次调用WriteBuffer都会通过WSASend投递一次IOCP请求，从而造成多次进入TSocketHandle的锁。WriteBuffer函数如下：procedure TSocketHandle.WriteBuffer(const ABuffer; const ACount: Integer; const AIocpOperate: TIocpOperate);var IocpRec: PIocpRecord; iErrCode: Integer; dSend, dFlag: DWORD;begin IocpRec := FSendOverlapped.Allocate(ACount); FillChar(IocpRec.Overlapped, SizeOf(IocpRec.Overlapped), 0); IocpRec.IocpOperate := AIocpOperate; System.Move(ABuffer, IocpRec.WsaBuf.buf^, ACount); dFlag := 0; if WSASend(FSocket, @IocpRec.WsaBuf, 1, dSend, dFlag, @IocpRec.Overlapped, nil) = SOCKET_ERROR then beginiErrCode := WSAGetLastError;if iErrCode <> ERROR_IO_PENDING thenbeginFIocpServer.DoError(‘WSASend’, GetLastWsaErrorStr);ProcessNetError(iErrCode);end; end; end;解决办法是我们把发送引入缓存机制，把发送的数据缓存在内存中，最后调用函数一次发送，具体实现函数分为打开发送缓存和Flush发送缓存，代码如下：procedure TSocketHandle.OpenWriteBuffer;begin if Assigned(FOutputBuf) thenFreeAndNil(FOutputBuf); FOutputBuf := TMemoryStream.Create;end;procedure TSocketHandle.FlushWriteBuffer(const AIocpOperate: TIocpOperate);var IocpRec: PIocpRecord; iErrCode: Integer; dSend, dFlag: DWORD;begin IocpRec := FSendOverlapped.Allocate(FOutputBuf.Size); IocpRec.Overlapped.Internal := 0; IocpRec.Overlapped.InternalHigh := 0; IocpRec.Overlapped.Offset := 0; IocpRec.Overlapped.OffsetHigh := 0; IocpRec.Overlapped.hEvent := 0; IocpRec.IocpOperate := AIocpOperate; System.Move(PAnsiChar(FOutputBuf.Memory)[0], IocpRec.WsaBuf.buf^, FOutputBuf.Size); dFlag := 0; if WSASend(FSocket, @IocpRec.WsaBuf, 1, dSend, dFlag, @IocpRec.Overlapped, nil) = SOCKET_ERROR then beginiErrCode := WSAGetLastError;if iErrCode <> ERROR_IO_PENDING thenbeginFIocpServer.DoError(‘WSASend’, GetLastWsaErrorStr);ProcessNetError(iErrCode);end; end; FreeAndNil(FOutputBuf);end;调用写入函数就是先写入缓存，具体实现代码如下：procedure TSocketHandle.WriteBuffer(const ABuffer; const ACount: Integer);begin FOutputBuf.WriteBuffer(ABuffer, ACount);end;procedure TSocketHandle.WriteWord(AValue: Word; const AConvert: Boolean = True);begin if AConvert thenAValue := htons(AValue); WriteBuffer(AValue, SizeOf(AValue));end;procedure TSocketHandle.WriteCardinal(AValue: Cardinal; const AConvert: Boolean);begin if AConvert thenAValue := htonl(AValue); WriteBuffer(AValue, SizeOf(AValue));end;procedure TSocketHandle.WriteInteger(AValue: Integer; const AConvert: Boolean);begin WriteCardinal(Cardinal(AValue), AConvert);end;procedure TSocketHandle.WriteSmallInt(AValue: SmallInt; const AConvert: Boolean);begin WriteWord(Word(AValue), AConvert);end;procedure TSocketHandle.WriteString(const AValue: string);var iLen: Integer;begin iLen := Length(AValue); if iLen > 0 thenWriteBuffer(PChar(AValue)^, iLen);end;procedure TSocketHandle.WriteLn(const AValue: string);begin WriteString(AValue + EOL);end;改造后的服务器下发响应函数如下：procedure TBaseSocket.DoSendResult(const AWriteNow: Boolean);var wLen: Word; cLen: Cardinal; utf8Buff: UTF8String;begin if not Connected then Exit; if AWriteNow thenOpenWriteBuffer; utf8Buff := AnsiToUtf8(FResponse.Text); //转为UTF8 if LenType = ltWord then beginwLen := Length(utf8Buff) + SizeOf(Cardinal); //总长度WriteWord(wLen, False); end else if LenType = ltCardinal then begincLen := Length(utf8Buff) + SizeOf(Cardinal); //总长度WriteCardinal(cLen, False); end; WriteCardinal(Length(utf8Buff), False); //下发命令长度 WriteBuffer(PUTF8String(utf8Buff)^, Length(utf8Buff)); //命令内容 if AWriteNow thenFlushWriteBuffer(ioWrite); //直接发送end;
客户端优化
木已成舟便要顺其自然
