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https://issues.apache.org/jira/browse/LOG4NET-415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13867469#comment-13867469
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Dongsheng Song commented on LOG4NET-415:
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JL, you only see BeginSend use double times (14 us vs 31 us), but forget
log4net use more times.
e.g. In my testing, log4net use about 50us to format messages to byte array,
then the difference is
64 us vs 81 us, a little difference.
If you can not accept 17 us extra cost, you should not log messages, then you
can gain more times (64 us).
PS: UDP has best efforts nature, but set Blocking=failse, without resend when
OS buffer is full, is not best efforts.
> 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, MessageLostTest.cs,
> MessageLostTest.cs, MessageLostTestAsync.cs, RemoteSyslogNonBlockingv2.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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