[D] Does Log4j2 compress rolled log files concurrently with wr iting to the new log file? [logging-log4j2]

GitHub user stoyanpetrov1920-spec created a discussion: Does Log4j2 compress rolled log files concurrently with writing to the new log file?

In Log4j 2, when using a DirectWriteRolloverStrategy with compression enabled (e.g., filePattern="app-%d{yyyy-MM-dd}.log.xz"), does the framework perform compression of the rolled file and writing to the new active log file concurrently?

In other words, after a rollover trigger (time or size-based), does Log4j start writing new log events to the fresh file immediately while compressing the old file in a background thread — or does the compression need to finish before logging resumes?

I couldn’t find a clear statement about this behavior in the official Log4j 2 documentation or API reference. Any pointers or clarification on whether compression and new file writes happen in parallel would be appreciated.

The reason I’m asking is that our team is evaluating switching from gzip to xz compression for rolled files. However, xz compression time for ~100 MB logs is quite high. If rollover and writing to the new file occur sequentially, that delay might block logging and impact performance, so we may need to consider other strategies.

GitHub link: https://github.com/apache/logging-log4j2/discussions/3964

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