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https://issues.apache.org/jira/browse/LOG4NET-415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13865013#comment-13865013
]
Dongsheng Song commented on LOG4NET-415:
----------------------------------------
Just Set Socket.Blocking to false is not correct non-block programing,
this will cause huge unexpected message lost.
Here is a demo:
Message lost rate: 32.61 %, 32.61 %
Message lost rate: 32.90 %, 32.76 %
Message lost rate: 27.28 %, 30.81 %
Message lost rate: 55.46 %, 36.56 %
...
Here is my test code:
class MessageLostTest
{
private static long _messageCount;
private static long _errorCount;
private static void Main()
{
Socket socket = new Socket(AddressFamily.InterNetwork,
SocketType.Dgram, ProtocolType.Udp);
socket.Connect("192.168.30.233", 514);
socket.Blocking = false;
new Thread(delegate(object obj)
{
long m = _messageCount, e = _errorCount;
while (true)
{
Thread.Sleep(5000);
long m2 = Interlocked.Read(ref _messageCount);
long e2 = Interlocked.Read(ref _errorCount);
Console.WriteLine("Message lost rate: {0:##.00 %}, {1:
##.00 %}",
(e2 - e) / (double)(m2 - m), e2 /
(double)m2);
m = m2; e = e2;
}
}).Start();
byte[] message = new byte[400];
while (true)
{
try
{
if (socket.Send(message) != message.Length)
Interlocked.Increment(ref _errorCount);
Interlocked.Increment(ref _messageCount);
}
catch (Exception e)
{
Interlocked.Increment(ref _errorCount);
//Console.WriteLine("Socket.Send failed: {0}{1}{2}",
e.Message, Environment.NewLine, e.StackTrace);
}
}
}
}
> RemoteSyslogAppender may block for ARP resolution + Improvement Strict RFC3164
> ------------------------------------------------------------------------------
>
> Key: LOG4NET-415
> URL: https://issues.apache.org/jira/browse/LOG4NET-415
> Project: Log4net
> Issue Type: Bug
> Components: Appenders
> Affects Versions: 1.2.13
> Environment: Any Windows environment
> Reporter: Jose Luis Pedrosa
> Labels: RemoteSyslogAppender
> Attachments: LOG4NET-415.patch
>
>
> Sending UDP packages may block for some time in specific circumstances:
> 1) Next hop in network level 3 can't be resolved by ARP.
> 2) Datagram size exceeds FastSendDatagramThreshold configured size.
> When sending packets bigger than FastSendDatagramThreshold, the OS waits
> until the packet is actually sent, if the If the syslog (or the next hop to
> reach the syslog) is in the same VLAN/Subnet the OS tries to resolve by ARP
> the Ip of the configured syslog, this may take up to 3 seconds, slowing down
> the whole application, which in some cases can lead to outages (timeouts, DB
> locks...).
> Also the fact that each carriage return generates the headers of the packet
> again, that can lead to a significant overhead in some scenarios, for
> instance when loggign HTTP requests to a remote syslog, every header will go
> in a different message. Also some logging may require characters that are now
> skipped in patch: https://issues.apache.org/jira/browse/LOG4NET-370
> I'm adding a patch that
> 1) Moves the use of UDPClient to Non blocking sockets, which eliminates the
> blocking.
> 2) Adds a configuration field to decide if you want Strict RFC Behaviour or
> not (with default Strict).
> Please your feedback, thanks in advance
> Jose Luis
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