Performance Within Reach » GC http://unmanageability.com Performance Within Reach Sat, 17 Jul 2010 19:19:53 +0000 en hourly 1 http://wordpress.org/?v=3.0 A full collection happens when… http://unmanageability.com/index.php/2006/10/30/a-full-collection-only-happens-when/ http://unmanageability.com/index.php/2006/10/30/a-full-collection-only-happens-when/#comments Mon, 30 Oct 2006 00:05:33 +0000 Coder http://blog.codeperformance.com/index.php/2006/10/30/a-full-collection-only-happens-when/ Jon Masamitsu’s Weblog : Weblog

The garbage collector tracks the average of the rate of promotion of live objects from the young generation into the tenured generation. If the average exceeds the free space in the tenured generation, the next time the young generation fills up, a full collection is done instead of a minor collection.

There are some caveats to this, read on…

]]> http://unmanageability.com/index.php/2006/10/30/a-full-collection-only-happens-when/feed/ 0 How does [CMS (concurrent mode failure):...] happen? http://unmanageability.com/index.php/2006/04/17/how-does-cms-concurrent-mode-failure-happen/ http://unmanageability.com/index.php/2006/04/17/how-does-cms-concurrent-mode-failure-happen/#comments Sun, 16 Apr 2006 18:59:34 +0000 Coder http://codeperformance.com/index.php/2006/04/17/how-does-cms-concurrent-mode-failure-happen/ Jon Masamitsu’s Weblog

The amount of live data that is in the tenured generation is too large. Specifically, there is not enough free space in the tenured generation to support the rate of allocation into the tenured generation.

]]> http://unmanageability.com/index.php/2006/04/17/how-does-cms-concurrent-mode-failure-happen/feed/ 0 GC ergonomics just works within the limits of the heap it’s given http://unmanageability.com/index.php/2006/01/04/gc-ergonomics-just-works-within-the-limits-of-the-heap-its-given/ http://unmanageability.com/index.php/2006/01/04/gc-ergonomics-just-works-within-the-limits-of-the-heap-its-given/#comments Wed, 04 Jan 2006 00:14:55 +0000 Coder http://codeperformance.com/index.php/2006/01/04/gc-ergonomics-just-works-within-the-limits-of-the-heap-its-given/ Jon Masamitsu’s Weblog

Ergomonics has a default for the relative sizes of the young generation and the tenured generation in the heap. If you have command line flags to specify the sizes of the generations (probably something like -XX:NewRatio=ratio or -XX:MaxNewSize=bytes), use them. GC ergonomics normally does not change the maximum size of a generation so if you know something about how your application runs such that you know it benefits from a larger or smaller young generation, pass that information along on the command line. Again GC ergonomics just works within the limits of the heap it’s given.

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