我有一个 .NET Core 2.0 应用程序，需要迭代很多文件（共计 6,0000 个），这些文件大小不同（总共 220GB）。
我使用以下方式枚举它们：
我使用以下方式枚举它们：
new DirectoryInfo(TargetPath)
.EnumerateFiles("*.*", SearchOption.AllDirectories)
.GetEnumerator()
并使用它们进行迭代
Parallel.ForEach(contentList.GetConsumingEnumerable(),
new ParallelOptions
{
MaxDegreeOfParallelism = Environment.ProcessorCount * 2
},
file => ...
在此之内，我有一系列的正则表达式列表，然后使用它们扫描文件。
Parallel.ForEach(_Rules,
new ParallelOptions
{
MaxDegreeOfParallelism = Environment.ProcessorCount * 2
},
rule => ...
最后，我使用 Regex 类的一个 实例 来获取匹配项
RegEx = new Regex(
Pattern.ToLowerInvariant(),
RegexOptions.Multiline | RegexOptions.Compiled,
TimeSpan.FromSeconds(_MaxSearchTime))
private void GetFiles(string TargetPath, BlockingCollection<FileInfo> ContentCollector)
{
List<FileInfo> results = new List<FileInfo>();
IEnumerator<FileInfo> fileEnum = null;
FileInfo file = null;
fileEnum = new DirectoryInfo(TargetPath).EnumerateFiles("*.*", SearchOption.AllDirectories).GetEnumerator();
while (fileEnum.MoveNext())
{
try
{
file = fileEnum.Current;
//Skip long file names to mimic .Net Framework deficiencies
if (file.FullName.Length > 256) continue;
ContentCollector.Add(file);
}
catch { }
}
ContentCollector.CompleteAdding();
}
在我的 Rule 类中，以下是相关的方法：
_RegEx = new Regex(Pattern.ToLowerInvariant(), RegexOptions.Multiline | RegexOptions.Compiled, TimeSpan.FromSeconds(_MaxSearchTime));
...
public MatchCollection Matches(string Input) { try { return _RegEx.Matches(Input); } catch { return null; } }
public MatchCollection Matches2(string Input) { try { return Regex.Matches(Input, Pattern.ToLowerInvariant(), RegexOptions.Multiline, TimeSpan.FromSeconds(_MaxSearchTime)); } catch { return null; } }
那么，这里是匹配代码：
public List<SearchResult> GetMatches(string TargetPath)
{
//Set up the concurrent containers
ConcurrentBag<SearchResult> results = new ConcurrentBag<SearchResult>();
BlockingCollection<FileInfo> contentList = new BlockingCollection<FileInfo>();
//Start getting the file list
Task collector = Task.Run(() => { GetFiles(TargetPath, contentList); });
int cnt = 0;
//Start processing the files.
Task matcher = Task.Run(() =>
{
//Process each file making it as parallel as possible
Parallel.ForEach(contentList.GetConsumingEnumerable(), new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount * 2 }, file =>
{
//Read in the whole file and make it lowercase
//This makes it so the Regex engine does not have
//to do it for each 175 patterns!
StreamReader stream = new StreamReader(File.OpenRead(file.FullName));
string inputString = stream.ReadToEnd();
stream.Close();
string inputStringLC = inputString.ToLowerInvariant();
//Run through all the patterns as parallel as possible
Parallel.ForEach(_Rules, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount * 2 }, rule =>
{
MatchCollection matches = null;
int matchCount = 0;
Stopwatch ruleTimer = Stopwatch.StartNew();
//Run the match for the rule and then get our count (does the actual match iteration)
try
{
//This does not work - Causes Deadlocks:
//matches = rule.Matches(inputStringLC);
//This works - No Deadlocks;
matches = rule.Matches2(inputStringLC);
//Process the regex by calling .Count()
if (matches == null) matchCount = 0;
else matchCount = matches.Count;
}
//Catch timeouts
catch (Exception ex)
{
//Log the error
string timeoutMessage = String.Format("****** Regex Timeout: {0} ===> {1} ===> {2}", ruleTimer.Elapsed, rule.Pattern, file.FullName);
Console.WriteLine(timeoutMessage);
matchCount = 0;
}
ruleTimer.Stop();
if (matchCount > 0)
{
cnt++;
//Iterate the matches and generate our match records
foreach (Match match in matches)
{
//Fill my result object
//...
//Add the result to the collection
results.Add(result);
}
}
});
});
});
//Wait until all are done.
Task.WaitAll(collector, matcher);
Console.WriteLine("Found {0:n0} files with {1:n0} matches", cnt, results.Count);
return results.ToList();
}
更新2
我运行的测试没有死锁，但当它接近结束时，似乎停滞了，但我仍然可以用VS进入进程。然后我意识到我没有在我的测试中设置超时，而我在发布的代码中设置了超时（rule.Matches和rule.Matches2）。“有”超时，它会死锁。“没有”超时，它不会死锁。两者在.NET Framework 4.6中仍然有效。因为某些模式在一些大文件上会停顿，所以我需要为正则表达式设置超时。
更新3: 我一直在尝试不同的超时值，似乎是线程运行、超时异常和超时值的某种组合导致Regex引擎死锁。我无法确定确切的原因，但超时时间≥5分钟似乎有所帮助。作为临时解决办法，我可能会将该值设置为10分钟，但这不是永久解决方案！
GetMatches中的Parallel.ForEach。 - JohnyLBlockingCollection。只需让GetFiles返回一个IEnumerable并且为每个文件使用yield return。这样可以完全摆脱任务。你不需要内部的Parallel.ForEach（只需使用常规的foreach），并且可以利用线程本地变量而不是results。 - Rob