Jose Luis Pedrosa created LOG4NET-415:
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Summary: 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 Windows environment
Reporter: Jose Luis Pedrosa
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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