Java performance: Difference between revisions

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===Multi-core performance===
The scalability and performance of Java applications on multi-core systems is limited by the object allocation rate. This effect is sometimes called an "allocation wall".<ref>Yi Zhao, Jin Shi, Kai Zheng, Haichuan Wang, Haibo Lin and Ling Shao, [http://portal.acm.org/citation.cfm?id=1640116 Allocation wall: a limiting factor of Java applications on emerging multi-core platforms], Proceedings of the 24th ACM SIGPLAN conference on Object oriented programming systems languages and applications, 2009.</ref> However, in practice, modern garbage collector algorithms use multiple cores to perform garbage collection, which to some degree alleviates this problem. Some garbage collectors are reported to sustain allocation rates of over a gigabyte per second,<ref>[{{Cite web |url=http://www.azulsystems.com/sites/default/files/images/c4_paper_acm_0.pdf |title=C4: The Continuously Concurrent Compacting Collector] |access-date=October 29, 2013 |archive-date=August 9, 2014 |archive-url=https://web.archive.org/web/20140809222603/http://www.azulsystems.com/sites/default/files/images/c4_paper_acm_0.pdf |url-status=dead }}</ref> and there exist Java-based systems that have no problems scaling to several hundreds of CPU cores and heaps sized several hundreds of GB.<ref>[https://www.theregister.co.uk/2007/06/15/azul_releases_7200_systems/ Azul bullies Java with 768 core machine]</ref>
 
Automatic memory management in Java allows for efficient use of lockless and immutable data structures that are extremely hard or sometimes impossible to implement without some kind of a garbage collection.{{citation needed|date=September 2018}} Java offers a number of such high-level structures in its standard library in the java.util.concurrent package, while many languages historically used for high performance systems like C or C++ are still lacking them.{{citation needed|date=September 2017}}