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2010-02-19T14:26:41.907
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2012-07-29T14:57:29.353
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2012-07-29T14:57:29.353
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You should be able to query all collections or single one with Object Query Language (OQL) in <a href="http://java.sun.com/javase/6/docs/technotes/tools/share/jhat.html" rel="nofollow noreferrer">jhat</a>. You can't necessarily invoke arbitrary methods but you can write some complicated queries using the available functions. A. Sundararajan has some interesting blog posts on the subject that showcase what you can do. See <a href="http://blogs.oracle.com/sundararajan/entry/querying_java_heap_with_oql" rel="nofollow noreferrer">here</a> and <a href="http://blogs.oracle.com/sundararajan/entry/permanent_generation_analysis_with_oql" rel="nofollow noreferrer">here</a>. For instance, you can find all instances of <code>java.util.HashMap</code> that have a key test with the following query: <pre><code>select s from java.util.HashMap s where contains(s.table, function(it) { if (it && it.key && it.key.value && it.key.value.toString() == 'test') { return true; } return false; }) </code></pre> This should find the same key in a <code>java.util.concurrent.ConcurrentHashMap</code>: <pre><code>select s from java.util.concurrent.ConcurrentHashMap s where contains(s.segments, function(it) { if (!it || !it.table) { return false; } var i, e; for (i=0; i < it.table.length; i = i + 1) { e = it.table[i]; if (e) { return e.key && e.key.value && e.key.value.toString() == 'test'; } } return false; }) </code></pre>
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1. POTools for querying collections in heap dump
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1. USBill the Lizard
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1. USKevin
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1. COThanks - I hadn't really realised that OQL was that powerful. Perhaps when I have time I will write a tool to allow 'proper' querying of collections, but these OQL queries will do what I want for now!
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Querying!

Guidance

A row detail

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