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From "Benjamin Reed (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-40) Memory management in BigDataBag is probably wrong
Date Wed, 12 Dec 2007 23:31:43 GMT

    [ https://issues.apache.org/jira/browse/PIG-40?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12551159
] 

Benjamin Reed commented on PIG-40:
----------------------------------

How about 

class MemoryManager {
    static MemoryManager getMemoryManager();
    void add(Spillable spillable);
}

add() will put Spillable on a WeakList so that the Spillable object will get GCed when strong
references go away.

> Memory management in BigDataBag is probably wrong
> -------------------------------------------------
>
>                 Key: PIG-40
>                 URL: https://issues.apache.org/jira/browse/PIG-40
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>            Reporter: Sam Pullara
>            Assignee: Benjamin Reed
>         Attachments: BigDataBag.java, MemoryUsage.java
>
>
> src/org/apache/pig/data/BigDataBag.java
> 1) You should not use finalizers for things other than external resources -- using them
here is very dangerous and could inadvertantly lead to deadlocks and object resurrection and
just decreases performance without any advantage.
> 2) Using .freeMemory() the way it is used in this class is broken.  freeMemory() is going
to return a mostly random number between 0 and the real amount.  Adding gc() in here is a
terrible performance burden.  If you really want to do something like this you should using
softreferences and finalization queues.

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