为什么log4net线程会等待？

Question

上周,我们的一个测试服务器用完了日志驱动器上的磁盘空间.在释放磁盘空间后,我仍然有几个带调用堆栈的线程似乎被卡在log4net AppenderSkeleton.DoAppend中,这让我感到困惑,因为我期望log4net是线程安全的.

1. 在看到线程卡住时,我是否正确读取堆栈？
2. 堆栈是否表示线程卡在"锁定(此)"或其他位置？我的猜测在其他地方,因为我希望看到像Monitor.Enter这样的东西,如果它被锁定(这个).
3. 其中一个主题似乎在转换到新文件的过程中显示DoAppend.是否可以在创建此文件时阻止所有DoAppend线程？但是,我希望在释放磁盘空间后,这些线程会被解除阻塞.

任何帮助理解为什么log4net似乎被困在如此多的线程中,这是值得赞赏的.

下面是一个示例调用堆栈,显示在DoAppend内等待时阻塞的线程:

ntdll.dll!_ NtWaitForMultipleObjects @ 20()+ 0x15 bytes
ntdll.dll!_NtWaitForMultipleObjects@20()+ 0x15 bytes
KERNELBASE.dll!_WaitForMultipleObjectsEx@20()+ 0x36 bytes kernel32.dll!_WaitForMultipleObjectsExImplementation@20()+ 0x8e bytes [管理到本机转换]
log4net.dll!log4net.Appender.AppenderSkeleton.DoAppend(log4net.Core.LoggingEvent loggingEvent)+ 0x3e 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字节

这是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;
        }
    }
}

这是我的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>

正在滚动到新文件的DoAppend堆栈

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

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 bytes
[管理到本机转换]
log4net.dll!log4net.Appender.AppenderSkeleton.DoAppend(log4net.Core.LoggingEvent loggingEvent)+ 0x3e 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,对象消息,System.Exception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,还有一个线程似乎被阻止尝试翻转.

MSVCR120_CLR0400.dll!_memcpy()+ 0x21e bytes
[管理到本机转换]
mscorlib.dll!System.Buffer._Memcpy(byte*dest,byte*src,int len)484行+ 0x20字节C#mscorlib.dll!System.Buffer .Memcpy(byte*dest,byte*src,int len)第401行C#mscorlib.dll!string.FillStringChecked(string dest,int destPos,string src)第1523行+ 0xf字节C#mscorlib.dll!string.ConcatArray(string [ ]值,int totalLength)行3340 C#mscorlib.dll!string.Concat(object [] args)行3180 + 0xa字节C#log4net.dll!log4net.Appender.FileAppender.OpenFile(string fileName,bool append)+ 0x162 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

Answer 1

我在堆栈溢出中多次看到 log4net 的这种行为。当您用完磁盘空间时，fileappender 似乎开始阻塞。我猜这是附加程序中的一个错误，因此将其记录为错误似乎适合这种情况。