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I was asked about the feasibility of adding automatic leak detection to a CI pipeline. And I realized that it's easily doable ...

1. Make sure GC logging is on (to a well defined location).
2. Set the GC algorithm to parallel GC (doesn't matter if a different one is used in production, that doesn't change memory leaking, and this is for a specific "memory leak regression" CI stage). Also set Xmx=Xms and Xmn values to eliminate variability in the heap adjusting itself internally.
3. Scan for only the full/major/oldgen GCs and extract the "heap after the GC completes" (that's why to use parallel GC, it's easy to extract these from the logs).
4. If the sequence becomes increasing and above a threshold (say above 2/3 the allocated heap size) then you have a leak.

But note that you have to run it long enough for the leak to show. Now on to this month's tips, tools, news, articles, and talks from our extensive community. And of course the tips from this month's articles and talks, as ever are extracted into this month's tips page.

A note from this newsletter's sponsor

News

Java performance tuning related news.

• Proposal to add records and sealed types to Java. The performance implications are not obvious at this stage, unlike value types which clearly help with memory layout and will improve performance for a range of cases
• LockSupport.parkNanos() resolution on Linux and how to change it
• LockSupport.parkNanos() resolution on Windows and how to change it
• -XX:+AggressiveOpts was deprecated in Java 11 and is gone in Java 12

Tools

Java performance tuning related tools.

• high performance on-heap caching library
• high performance on-heap caching library
• A microbenchmarking test framework for Adopt OpenJDK
• Tools for openjdk testing

Articles

• The Trouble with Memory (Kirk Pepperdine/QCon)
• "Quantum" Performance Effects: beyond the Core (Sergey Kuksenko/QCon)
• Scaling up Performance Benchmarking (Anil Kumar, Monica Beckwith/QCon)
• Continuous Profiling in Java (Richard Warburton, Sadiq Jaffer/VirtualJUG)

Jack Shirazi

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