[jira] [Commented] (ACCUMULO-24) Improve messaging regarding non-native map memory use

["Eric Newton (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-24?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13127477#comment-13127477 ] 

Eric Newton commented on ACCUMULO-24:
-------------------------------------

There's code to do this already (TabletServerResourceManager). 

                Runtime runtime = Runtime.getRuntime();
		if (!usingNativeMap && maxMemory > runtime.maxMemory()) {
		    throw new IllegalArgumentException(...);
		}
		runtime.gc();
		if (!usingNativeMap && maxMemory > runtime.freeMemory()) {
		    log.warn("In-memory map may not fit into local memory space.");
		}

We've had users run out of memory, but apparently, they still pass this test.  This is not surprising, there is a lot of other overhead in the JVM besides mutations in the in-memory map.  We should determine what that overhead is, and include it in this check.

                
> Improve messaging regarding non-native map memory use
> -----------------------------------------------------
>
>                 Key: ACCUMULO-24
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-24
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: tserver
>    Affects Versions: 1.4.0
>            Reporter: John Vines
>            Assignee: Keith Turner
>            Priority: Minor
>              Labels: improvement, memory
>             Fix For: 1.4.0
>
>
> We should compute a smaller size to use for the non-native in memory map when the users settings are too large for the JVM setting. There should be proper warning when this takes place.

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