C# 为什么log4net线程停留在等待状态？

上周，我们的一个测试服务器的日志驱动器上的磁盘空间用完了。释放磁盘空间后，我仍然有几个线程带有调用堆栈，它们似乎卡在log4net AppenderSkeleton.DoAppend中，这让人困惑，因为我希望log4net是线程安全的

看到线程被卡住时，我读的堆栈是否正确

堆栈是否指示线程卡在“锁定（此）”或其他位置？我的猜测在别处，因为我希望看到类似Monitor.Enter这样的东西，如果它卡在锁上（这个）

一个线程在滚动到一个新文件的过程中似乎显示了DOOPEND。是否所有DoAppend线程在创建此文件时都被阻止？但是，我希望在释放磁盘空间后，这些线程将被解除阻塞 如果您能帮助我们理解为什么log4net似乎被这么多线程卡住，我们将不胜感激。

下面是一个示例调用堆栈，显示DoAppend内部等待时阻塞的线程：

ntdll.dll_NtWaitForMultipleObjects@20（）+0x15字节
ntdll.dll_NtWaitForMultipleObjects@20（）+0x15字节
KERNELBASE.dll_WaitForMultipleObjectsEx@20（）+0x36字节 内核32.dll_WaitForMultipleObjectsExImplementation@20（）+0x8e字节 [管理到本机转换]
log4net.dll！log4net.Appender.AppenderSkeleton.DoAppend（log4net.Core.LoggingEvent LoggingEvent）+0x3e字节 log4net.dll！log4net.Util.AppenderAttachedImpl.AppenderLoopOnAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa0字节
log4net.dll！log4net.Repository.Hierarchy.Logger.CallAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa9字节
log4net.dll！log4net.Repository.Hierarchy.Logger.ForcedLog（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x4a字节
log4net.dll！log4net.Repository.Hierarchy.Logger.Log（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x5e字节
log4net.dll！log4net.Core.LogImpl.Info（对象消息）+0x27字节

这是来自log4net AppenderSkeleton.DoAppend的源代码

public void DoAppend(LoggingEvent loggingEvent) 
{
    // This lock is absolutely critical for correct formatting
    // of the message in a multi-threaded environment.  Without
    // this, the message may be broken up into elements from
    // multiple thread contexts (like get the wrong thread ID).

    lock(this)
    {
        if (m_closed)
        {
            ErrorHandler.Error("Attempted to append to closed appender named ["+m_name+"].");
            return;
        }

        // prevent re-entry
        if (m_recursiveGuard)
        {
            return;
        }

        try
        {
            m_recursiveGuard = true;

            if (FilterEvent(loggingEvent) && PreAppendCheck())
            {
                this.Append(loggingEvent);
            }
        }
        catch(Exception ex)
        {
            ErrorHandler.Error("Failed in DoAppend", ex);
        }
#if !MONO && !NET_2_0
        // on .NET 2.0 (and higher) and Mono (all profiles), 
        // exceptions that do not derive from System.Exception will be
        // wrapped in a RuntimeWrappedException by the runtime, and as
        // such will be catched by the catch clause above
        catch
        {
            // Catch handler for non System.Exception types
            ErrorHandler.Error("Failed in DoAppend (unknown exception)");
        }
#endif
        finally
        {
            m_recursiveGuard = false;
        }
    }
}

以下是我的log4net设置：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net" />
  </configSections>
  <log4net xsi:noNamespaceSchemaLocation="log4net.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="g:\logfiles\mySerivceName\" />
      <appendToFile value="true" />
      <rollingStyle value="Date" />
      <datePattern value="'myServiceName.'yyyy-MM-dd-HH'-00.log'"/>
      <staticLogFileName value="false" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date{yyyy-MM-dd HH:mm:ss.fff} %-5level [%3thread] [%-50.50stacktrace] %message %newline"/>
      </layout>
      <filter type="log4net.Filter.LevelRangeFilter">
        <levelMin value="INFO" />
        <levelMax value="FATAL" />
      </filter>
    </appender>
    <appender name="SmtpAppender" type="log4net.Appender.SmtpAppender">
        <to value="alerts@myCompanyName.com" />
        <from value="servicename@localnetwork" />
        <subject value="${COMPUTERNAME} - Error Generated" />
        <smtpHost value="mySmtpServerIpAddress" />
        <bufferSize value="2" />
        <lossy value="true" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date{yyyy-MM-dd HH:mm:ss.fff} %-5level [%3thread] [%-50.50stacktrace] %message %newline" />
        </layout>
        <filter type="log4net.Filter.LevelRangeFilter">
            <levelMin value="ERROR" />
            <levelMax value="FATAL" />
        </filter>
    </appender>
    <root>
      <level value="DEBUG"/>
      <appender-ref ref="RollingFileAppender" />
    </root>
  </log4net>
</configuration>

这是同一台机器上的另一个调用堆栈，不同的进程，也挂起：

clr.dll！AwareLock:：Contention（）+0x10d字节
[管理到本机转换]
log4net.dll！log4net.Appender.AppenderSkeleton.DoAppend（log4net.Core.LoggingEvent LoggingEvent）+0x3e字节 log4net.dll！log4net.Util.AppenderAttachedImpl.AppenderLoopOnAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa0字节
log4net.dll！log4net.Repository.Hierarchy.Logger.CallAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa9字节
log4net.dll！log4net.Repository.Hierarchy.Logger.ForcedLog（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x4a字节
log4net.dll！log4net.Repository.Hierarchy.Logger.Log（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x5e字节
log4net.dll！log4net.Core.LogImpl.Info（对象消息）+0x27字节

在同一台机器上的第二个进程中，还有一个线程似乎在试图翻滚时被阻塞

MSVCR120_CLR0400.dll_memcpy（）+0x21e字节
[管理到本机转换]
mscorlib.dll！System.Buffer.\u Memcpy（字节*dest，字节*src，int len）行484+0x20字节C# mscorlib.dll！System.Buffer.Memcpy（字节*dest，字节*src，int len）行401c# mscorlib.dll！string.FillStringChecked（string dest、int destPos、string src）行1523+0xf字节C# mscorlib.dll！string.ConcatArray（字符串[]值，整数总长度）第3340行C# mscorlib.dll！string.Concat（object[]args）行3180+0xa字节C# log4net.dll！log4net.Appender.FileAppender.OpenFile（字符串文件名，bool append）+0x162字节
log4net.dll！log4net.Appender.RollingFileAppender.OpenFile（字符串文件名，bool append）+0x189字节
log4net.dll！log4net.Appender.FileAppender.SafeOpenFile（字符串文件名，bool append）+0x2d字节
log4net.dll！log4net.Appender.FileAppender.PrepareWriter（）+0x13字节
log4net.dll！log4net.Appender.TextWriterAppender.PreAppendedCheck（）+0x32字节
log4net.dll！log4net.Appender.AppenderSkeleton.DoAppend（log4net.Core.LoggingEvent LoggingEvent）+0xe0字节 log4net.dll！log4net.Util.AppenderAttachedImpl.AppenderLoopOnAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa0字节
log4net.dll！log4net.Repository.Hierarchy.Logger.CallAppenders（log4net.Core.LoggingEvent LoggingEvent）+0xa9字节
log4net.dll！log4net.Repository.Hierarchy.Logger.ForcedLog（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x4a字节
log4net.dll！log4net.Repository.Hierarchy.Logger.Log（System.Type callerStackBoundaryDeclaringType、log4net.Core.Level、对象消息、系统异常）+0x5e字节
log4net.dll！log4net.Core.LogImpl.Info（对象消息）+0x27字节

---

我在这里多次看到log4net在堆栈溢出上的这种行为。当磁盘空间用完时，fileappender似乎开始阻塞。我猜这是appender中的一个bug，所以将其记录为bug似乎适合这种情况。

那么您是说这些错误来自CLR和内核？如果那是真的，我同意你的看法。但是调用堆栈的哪一部分让你得出这个结论呢？好吧，调用堆栈告诉我们这里有一个死锁。应用程序崩溃了还是仍在工作<代码>锁定本身不会超时，因此它被卡在某个地方试图锁定

mscorlib.dll!System.Text.StringBuilder.Append(char value) Line 953 + 0xb bytes
  mscorlib.dll!System.IO.PathHelper.Append(char value) Line 139 + 0x18 bytes
  mscorlib.dll!System.IO.Path.NormalizePath(string path, bool fullCheck, int maxPathLength, bool expandShortPaths) Line 620
  mscorlib.dll!System.IO.Path.GetDirectoryName(string path) Line 170 + 0x24 bytes
  log4net.dll!log4net.Appender.FileAppender.LockingModelBase.CreateStream(string filename, bool append, System.IO.FileShare fileShare) + 0x35 bytes     
  log4net.dll!log4net.Appender.FileAppender.ExclusiveLock.OpenFile(string filename, bool append, System.Text.Encoding encoding) + 0x2d bytes      
  log4net.dll!log4net.Appender.FileAppender.OpenFile(string fileName, bool append) + 0x1ac bytes  
  log4net.dll!log4net.Appender.RollingFileAppender.OpenFile(string fileName, bool append) + 0x189 bytes 
  log4net.dll!log4net.Appender.FileAppender.SafeOpenFile(string fileName, bool append) + 0x2d bytes     
  log4net.dll!log4net.Appender.FileAppender.PrepareWriter() + 0x13 bytes  
  log4net.dll!log4net.Appender.TextWriterAppender.PreAppendCheck() + 0x32 bytes 
  log4net.dll!log4net.Appender.AppenderSkeleton.DoAppend(log4net.Core.LoggingEvent loggingEvent) + 0xe0 bytes 
  log4net.dll!log4net.Util.AppenderAttachedImpl.AppendLoopOnAppenders(log4net.Core.LoggingEvent loggingEvent) + 0xa0 bytes      
  log4net.dll!log4net.Repository.Hierarchy.Logger.CallAppenders(log4net.Core.LoggingEvent loggingEvent) + 0xa9 bytes      
  log4net.dll!log4net.Repository.Hierarchy.Logger.ForcedLog(System.Type callerStackBoundaryDeclaringType, log4net.Core.Level level, object message, System.Exception exception) + 0x4a bytes      
  log4net.dll!log4net.Repository.Hierarchy.Logger.Log(System.Type callerStackBoundaryDeclaringType, log4net.Core.Level level, object message, System.Exception exception) + 0x5e bytes      
  log4net.dll!log4net.Core.LogImpl.Info(object message) + 0x27 bytes