项目需要，几十万张照片需要计算出每个照片的特征值（调用C++编写的DLL）。
业务流程：选择照片文件夹，分别访问照片-->调用DLL接口传递照片路径-->接收处理返回值-->写入数据库。
前期使用的for循环来处理，几十万张照片处理起来差不多10个小时。速度太慢，后面改进使用Parallel来进行平行计算（调用DLL处理照片），统一写入Datatable，然后使用BulkInsert批量把Datatable写入数据库，目前测试8万张照片并行计算速度30分钟，速度提高约30%-40%左右。
代码示例如下：
@H_502_9@private static sqlConnection sqlconn;
private static ConcurrentDictionary<string,int> currInts = new ConcurrentDictionary<string,int>();
private void Button1_Click(object sender,EventArgs e)
{
var dirPath = "";
using (var folderBrowser = new FolderBrowserDialog())
{
if (folderBrowser.ShowDialog() != DialogResult.OK) return;
dirPath = folderBrowser.SelectedPath;
if (!Directory.Exists(dirPath))
{
MessageBox.Show(@"所选路径不存在或无权访问",@"错误",MessageBoxButtons.OK,MessageBoxIcon.Error);
return;
}
}
BeginInvoke(new Action(async () =>
{
button1.Enabled = false;
var sw = new Stopwatch();
sw.Start();
//检测服务器链接
Log.WriteLine(@"尝试连接数据库服务器");
sqlconn = new sqlConnection(
$"Data Source={txt_serverIP.Text},{txt_ServerPort.Text};User ID={txt_User.Text};Password={txt_Pwd.Text};Initial Catalog={txt_DB.Text};Persist Security Info=False;Pooling=true;Min Pool Size=30;Max Pool Size=200;");
if (sqlconn.State == ConnectionState.Closed)
{
try
{
sqlconn.Open();
}
catch (Exception exception)
{
Log.WriteLine($@"连接数据库服务器【失败】-->{exception.Message}");
button1.Enabled = true;
return;
}
}
Log.WriteLine($@"连接数据库服务器【成功】{Environment.NewLine}获取未转换图片数据。。。");
var ds = new DataSet();
int.TryParse(txt_start.Text,out var start);
int.TryParse(txt_end.Text,out var end);
var sqlstrALL = "";
if (start == 0 || end == 0)
{
sqlstrALL = "SELECT * FROM ViewWeiZhuanHuan";
}
else
{
sqlstrALL = $"SELECT * FROM ViewWeiZhuanHuan WHERE {txt_mastKey.Text} BETWEEN {start} AND {end}";
}
var sqlcmd = new sqlCommand(sqlstrALL,sqlconn);
DataAdapter da = new sqlDataAdapter(sqlcmd);
da.Fill(ds);
if (ds.Tables.Count == 0 || ds.Tables[0].Rows.Count == 0)
{
Log.WriteLine("所有图片都已经转换完毕。");
sqlconn.Close();
return;
}
Log.WriteLine($"{ds.Tables[0].Rows.Count}个图片需要转换。");
var total = ds.Tables[0].Rows.Count;
var rowkey = comboBox1.SelectedValue.ToString();
var splitkey = txt_split.Text.Trim();
#region 定义数据保存
var dt = new DataTable();
dt.Columns.Add("zd1",typeof(int));
dt.Columns.Add("zd2",typeof(int));
dt.Columns.Add("zd3",typeof(string));
dt.Columns.Add("zd4",typeof(string));
dt.Columns.Add("zd5",typeof(string));
dt.Columns.Add("zd6",typeof(string));
#endregion
#region 并行执行
currInts.TryAdd("currInts",1);//初始化进度数字为1
await Task.Run(() =>
{
//使用8个cpu核心来运行
var result = Parallel.For(0,ds.Tables[0].Rows.Count,new ParallelOptions { MaxDegreeOfParallelism = 8},(rotIndex,state) =>
{
BeginInvoke(new Action(() =>
{
currInts.TryGetValue("currInts",out var currValue);
lb_process.Text = $@"{currValue}/{total}";//显示进度
var nextValue = currValue + 1;
currInts.TryUpdate("currInts",nextValue,currValue);//加1
}));
var fileDirPath = "";//根据选择的文件名格式，用填写的规则生成路径
var file = new List<string>{
$"{dirPath}\\{fileDirPath}\\{ksno}_fp1.jpg",$"{dirPath}\\{fileDirPath}\\{ksno}_fp2.jpg",$"{dirPath}\\{fileDirPath}\\{ksno}_fp3.jpg"};
foreach (var zwzp in file)
{
try
{
var model = ZwHelper.zwzhAsync($"{zwzp}").Result;//调用C++转换
if (model != null)
{
//并行计算下写入Datatable需要锁定才可以，否则会提示datatable索引损坏
lock (dt.Rows.SyncRoot)
{
var dr = dt.NewRow();
dr["zd1"] = Convert.ToInt32(filexe);
dr["zd2"] = Convert.ToInt32(ds.Tables[0].Rows[rotIndex]["zd1"]);
dr["zd3"] = model.zhtz;
dr["zd4"] = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
dr["zd5"] = "";
dr["zd6"] = "";
dt.Rows.Add(dr);
}
}
else
{
Log.WriteLine($@"{ksno}转换失败");
Log.Log.Error($"{ksno}转换失败。");
}
}
catch (Exception exception)
{
Log.Log.Error($"学号{ksno}，图片路径{zwzp}转换失败。{exception}");
}
}
});
sw.Stop();
Log.WriteLine($"转换耗时：{sw.ElapsedMilliseconds}毫秒");
Log.WriteLine($@"开始写入数据库,数量{dt.Rows.Count}");
#region 批量写入
if (dt.Rows.Count ==0)
{
Log.WriteLine(@"没有要写入的数据。");
return;
}
sw.Restart();
var sucess = false;
if (sqlHelper.BulkInsert(sqlconn,txt_TableName.Text.Trim(),dt,out var err))
{
sucess = true;
}
else
{
Log.Log.Error($"写入数据库失败==》{err}");
}
sw.Stop();
Log.WriteLine($"写入数据库是否成功=>{sucess}，耗时{sw.ElapsedMilliseconds}毫秒");
#endregion
});
#endregion
if (sqlconn.State == ConnectionState.Open)
{
sqlconn.Close();
}
button1.Enabled = true;
}));
}
@H_502_9@ /// <summary>
/// 批量插入
/// </summary>
/// <param name="conn">连接对象</param>
/// <param name="tableName">将泛型集合插入到本地数据库表的表名</param>
/// <param name="dataTable">要批量写入的Datatable</param>
/// <param name="err">错误时返回的信息</param>
public static bool BulkInsert(sqlConnection conn,string tableName,DataTable dataTable,out string err)
{
err = "";
if (dataTable == null || dataTable.Rows.Count == 0)
{
err = "要写入的数据为空";
return false;
}
var tran = conn.BeginTransaction();//开启事务
var bulkCopy = new sqlBulkCopy(conn,sqlBulkCopyOptions.KeepNulls,tran);
try
{
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}
bulkCopy.BatchSize = 1000;
bulkCopy.DestinationTableName = tableName;
bulkCopy.WriteToServer(dataTable);
tran.Commit();
return true;
}
catch (Exception e)
{
err = e.ToString();
tran.Rollback();
return false;
}
finally
{
bulkCopy.Close();
if (conn.State == ConnectionState.Open)
{
conn.Close();
}
}
}
原文链接：https://www.cnblogs.com/wdw984/p/10968808.html
