[LOG4J2-3430] Provide a SocketAppender using NIO with a "writeTimeout"

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.17.2
• Component/s: Appenders
• Assignee: Unassigned
• Reporter: Jiří Smolík
• Created: 08/Mar/22 19:38
• Updated: 08/Mar/22 19:42

Description

The existing SocketAppender is configurable to the maximum extent allowed by Socket, but none of the configuration options are capable of limiting execution time of the following write operation:

https://github.com/apache/logging-log4j2/blob/e2ee2f4dd9327eb1841023c3269ba12f5673e694/log4j-core/src/main/java/org/apache/logging/log4j/core/net/TcpSocketManager.java#L253

When the network or server is congested, the write operation may be blocked for a long time and because it is executed within a synchronized block, all other threads will wait for a lock, which causes at least a partial DoS of the calling application for as long as the congestion continues.

As explained by rgoers  here:
https://issues.apache.org/jira/browse/LOG4J2-3425

the solution is using Java NIO.

Besides the usual Socket configuration options, I also propose a "writeTimeout" option which would allow to control maximum execution time of write operations. By default, the timeout may be disabled (value of -1 or 0). When the timeout elapses, Log4j2 should probably throw a runtime exception, which can be caught and dealt with by the calling code.

See the related ticket for more information.