CMS: "premature" minor GCs w/ ParNew

Srinivas Ramakrishna ysr1729 at
Wed May 15 16:58:30 UTC 2013

Does it happen with a specific application?

You might want to print the gc cause and see. It could be related to
allocating very large objects (arrays). +PrintGCDetails and
+PrintHeapAtGC would provide additional data (but probably not the
cause, although that may have changed in more recent builds (JDK
8/hs25+? have lost track..)

-- ramki

On Wed, May 15, 2013 at 8:05 AM, Vladimir Ivanov
<vladimir.x.ivanov at> wrote:
> Hi,
> I see minor GCs occurring when young gen occupancy is very low, e.g.:
> [ParNew: 8446K->7381K(943744K), 0.0274200 secs]
> Does anybody know what provokes such "premature" GCs?
> There's no CMS concurrent cycle running or any other interesting GC events
> occurred around that moment - just a sequence of minor GCs with such
> outlier.
> Such premature minor GCs occur on a regular basis.
> JDK version: 6u37, 64-Bit Server VM (20.12-b01, mixed mode)
> Best regards,
> Vladimir Ivanov

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