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Tag Archives: GC

5 Tips for Reducing Your Java Garbage Collection Overhead

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What are some of the most useful tips for keeping your GC overhead low? With the upcoming-yet-delayed-once-again release of Java 9, the G1 (“Garbage First”) garbage collector is set to become the default collector of the HotSpot JVM. From the serial garbage collector all the way to the CMS collector, the JVM has seen many GC implementations throughout its lifetime, ...

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What is the fastest Garbage Collector in Java 8?

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OpenJDK 8 has several Garbage Collector algorithms, such as Parallel GC, CMS and G1. Which one is the fastest? What will happen if the default GC changes from Parallel GC in Java 8 to G1 in Java 9 (as currently proposed)? Let’s benchmark it. Benchmark methodology Run the same code 6 times with a different VM argument (-XX:+UseSerialGC, -XX:+UseParallelGC, -XX:+UseConcMarkSweepGC, ...

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GC tuning in practice

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Tuning Garbage Collection is no different from any other performance-tuning activities. Instead of giving in to temptation for tweaking random parts of the application, you need to make sure you understand the current situation and the desired outcome. In general it is as easy as following the following process: State your performance goals Run tests Measure Compare to goals Make ...

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What is Garbage Collection?

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The following is an example from our Garbage Collection Handbook which will be published in the forthcoming weeks. In the meanwhile, take your time to get yourself familiar with the basics of the Garbage Collection – this is going to be the very first chapter of the book. At the first sight, garbage collection should be dealing with what the name suggests – finding ...

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Logging stop-the-world pauses in JVM

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Different events can cause the JVM to pause all the application threads. Such pauses are called Stop-The-World (STW) pauses. The most common cause for an STW pause to be triggered is garbage collection (example in github) , but different JIT actions (example), biased lock revocation (example), certain JVMTI operations , and many more also require the application to be stopped. ...

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ChronicleMap – Java Architecture with Off Heap Memory

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My last post was written a couple of weeks ago and after some valid feedback I’d like to clarify a couple of points as a preface to this article. The main takeaway from ‘Creating millions of objects with Zero Garbage‘ should be that with Chronicle you are not ‘limited’ to using jvm allocated on-heap memory when writing a Java program. Maybe ...

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Creating Millions of Objects with Zero Garbage

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As noted in First rule of performance optimisation, garbage is the enemy of fast code. Not only can it destroy any sort of deterministic performance by employing the services of the garbage collector but we start filling our CPU caches with garbage that will cause expensive cache misses for our program. So, can we use Java without creating garbage? Is it possible, ...

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Turning on GC logging at runtime

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There is always the next JVM behaving badly. And you know by heart that if you just could have had those few startup options exposing some more information about what is going on, you might have stood a chance of actually fixing the goddamn thing. But nope, exactly the flag you need (be it -XX:+HeapDumpOnOutOfMemoryError or -XX:+PrintGCDetails) is always missing. ...

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