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https://issues.apache.org/jira/browse/GEODE-2035?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alberto Bustamante Reyes reassigned GEODE-2035:
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Assignee: Alberto Bustamante Reyes
> document how to use G1GC with geode
> -----------------------------------
>
> Key: GEODE-2035
> URL: https://issues.apache.org/jira/browse/GEODE-2035
> Project: Geode
> Issue Type: Task
> Components: docs
> Reporter: Darrel Schneider
> Assignee: Alberto Bustamante Reyes
> Priority: Major
>
> The geode docs should describe how to configure G1GC for geode.
> One issue is that if you use "gfsh start server --max-heap=SIZE" then it will
> automatically configure CMS which does not work with G1GC.
> So instead of using the "--max-heap" option we should tell them to use
> "--J-XmxSIZE".
> To configure G1GC use "--J-XX:+UseG1GC".
> If you find the geode resource manager does not detect crossing the eviction
> or critical threshold quickly enough then try using this option to make it
> more responsive: "--J-XX:MaxGCPauseMillis=VALUE" where VALUE should be a
> number less than 200 (which is the current G1GC default). We have done some
> limited testing with this value set to 1 and it does make the resource
> manager more responsive when combined with G1GC but it also increases the
> amount of time spent in gc.
> We also noticed that if the primary heap objects you allocate are large then
> G1GC can cause the JVM to report out of heap memory when it has only used 50
> percent of the heap. We saw this with tests in which all the geode region
> values were larger than 50 percent of the G1 region size. Oracle calls these
> "humongous" objects. The default G1 region size is 1m. You can increase it up
> to 32m (it is always a power of 2) by using this:
> "--J-XX:G1HeapRegionSize=32m". If you are using large values and want to use
> G1GC without increasing its RegionSize (or if you large values are bigger
> than 16m) then you could make your geode regions that will contain the large
> values off-heap. But even if you do that the large off-heap values will
> allocate temporary large heap values that G1GC will treat as humongous
> allocations even though they will be short lived. So consider using CMS if
> most of you values will result in humongous allocations.
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