[英]How can I improve the performance of this CopyTo method?
EDIT: I have now solved this.编辑:我现在已经解决了这个问题。 My answer posted below and will mark as solved when SO lets me.
我的答案发布在下面,当 SO 允许我时将标记为已解决。
I have a CopyTo (and a CopyToAsync) method to copy files in my C# application.我有一个 CopyTo(和一个 CopyToAsync)方法来复制 C# 应用程序中的文件。 I have found that it is actually quite slow to copy the files, compared to something like Xcopy.
我发现与 Xcopy 之类的东西相比,复制文件实际上很慢。
I extracted the core functionality of the copy method and placed it into a test console app to get the speed that it operates at versus Xcopy, and found the results actually quite different.我提取了 copy 方法的核心功能并将其放入测试控制台应用程序中,以获得它与 Xcopy 相比的运行速度,发现结果实际上完全不同。
The results I get are:我得到的结果是:
Async Method: 36.59 seconds - Average speed: 1512.63 mb/sec异步方法:36.59 秒 - 平均速度:1512.63 mb/sec
Sync Method: 36.49 seconds - Average speed: 1516.72 mb/sec同步方法:36.49 秒 - 平均速度:1516.72 mb/sec
XCOPY: 5.62 seconds - Average speed: 9842.11 mb/sec XCOPY:5.62 秒 - 平均速度:9842.11 mb/sec
All three of these used the exact same file, and the exact same destination.这三个都使用完全相同的文件和完全相同的目的地。
StreamExtensions class:流扩展 class:
public static class StreamExtensions
{
const int DEFAULT_BUFFER = 0x1000; // 4096 bits
public static async Task CopyToAsync(this Stream source, Stream destination, IProgress<long> progress, CancellationToken cancellationToken = default, int bufferSize = DEFAULT_BUFFER)
{
var buffer = new byte[bufferSize];
int bytesRead;
long totalRead = 0;
while ((bytesRead = await source.ReadAsync(buffer, 0, buffer.Length, cancellationToken)) > 0)
{
await destination.WriteAsync(buffer, 0, bytesRead, cancellationToken);
cancellationToken.ThrowIfCancellationRequested();
totalRead += bytesRead;
progress.Report(totalRead);
}
}
public static void CopyTo(this Stream source, Stream destination, IProgress<long> progress, int bufferSize = DEFAULT_BUFFER)
{
var buffer = new byte[bufferSize];
int bytesRead;
long totalRead = 0;
while ((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0)
{
destination.Write(buffer, 0, bytesRead);
totalRead += bytesRead;
progress.Report(totalRead);
}
}
}
The IProgress<long>
object is to report the file progress back to the calling method. IProgress<long>
object 是将文件进度报告回调用方法。
Example call implementation:示例调用实现:
// Asynchronous version
public static async Task CopyFileSetAsync(Dictionary<string, string> fileSet)
{
for (var x = 0; x < fileSet.Count; x++)
{
var item = fileSet.ElementAt(x);
var from = item.Key;
var to = item.Value;
int currentProgress = 0;
long fileSize = new FileInfo(from).Length;
IProgress<long> progress = new SynchronousProgress<long>(value =>
{
decimal fileProg = (decimal)(value * 100) / fileSize;
if (fileProg != currentProgress)
{
currentProgress = (int)fileProg;
OnUpdateFileProgress(null, new FileProgressEventArgs(fileProg));
}
});
using (var outStream = new FileStream(to, FileMode.Create, FileAccess.Write, FileShare.Read))
{
using (var inStream = new FileStream(from, FileMode.Open, FileAccess.Read, FileShare.Read))
{
await inStream.CopyToAsync(outStream, progress);
}
}
OnUpdateFileProgress(null, new FileProgressEventArgs(100)); // Probably redundant
}
}
// Synchronous version
public static void CopyFileSet(Dictionary<string, string> fileSet)
{
for (var x = 0; x < fileSet.Count; x++)
{
var item = fileSet.ElementAt(x);
var from = item.Key;
var to = item.Value;
int currentProgress = 0;
long fileSize = new FileInfo(from).Length;
IProgress<long> progress = new SynchronousProgress<long>(value =>
{
decimal fileProg = (decimal)(value * 100) / fileSize;
if (fileProg != currentProgress)
{
currentProgress = (int)fileProg;
OnUpdateFileProgress(null, new FileProgressEventArgs(fileProg));
}
});
using (var outStream = new FileStream(to, FileMode.Create, FileAccess.Write, FileShare.Read))
{
using (var inStream = new FileStream(from, FileMode.Open, FileAccess.Read, FileShare.Read))
{
inStream.CopyTo(outStream, progress, 1024);
}
}
OnUpdateFileProgress(null, new FileProgressEventArgs(100)); // Probably redundant
}
}
Is there something that's preventing this from running as fast as it could?有什么东西可以阻止它尽可能快地运行吗? I'm just stumped as to how much slower it is compared to copy.
我只是对它与复制相比慢了多少感到困惑。
EDIT: Fixed a typo where I forgot a single ` around IProgress编辑:修正了一个错字,我在 IProgress 周围忘记了一个 `
Thanks to Tom and xanatos , I answered my own question:感谢Tom和xanatos ,我回答了我自己的问题:
I misunderstood the impact of buffer size.我误解了缓冲区大小的影响。 I had only gone so far as 8192 bytes as the buffer size.
我只达到了 8192 字节作为缓冲区大小。 After taking on their suggestions, I increased the buffer size to 1mb (1048576 bytes), and this made a massive difference to the performance.
在接受了他们的建议后,我将缓冲区大小增加到 1mb(1048576 字节),这对性能产生了巨大的影响。
Async Method: 5.57 seconds - Average speed: 9938.68 mb/sec异步方法:5.57 秒 - 平均速度:9938.68 mb/sec
Sync Method: 5.52 seconds - Average speed: 10028.36 mb/sec同步方法:5.52 秒 - 平均速度:10028.36 mb/sec
XCOPY: 5.03 seconds - Average speed: 11007.84 mb/sec XCOPY:5.03 秒 - 平均速度:11007.84 mb/sec
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