Re: memory allocation for

"Brandon McCombs" <brandon.mccombs@THRWHITE.remove-dii-this>
Wed, 27 Apr 2011 15:28:29 GMT
Brandon McCombs wrote:

Daniel Pitts wrote:

Brandon McCombs wrote:


My application makes multiple JNDI search calls to a directory server.
The search method returns a NamingEnumeration of SearchResults and I run
through a while loop that converts the enumeration to a Vector of
SearchResults. At another time I process the Vector to add the
SearchResults to a ListModel for viewing their properties.

My application takes up a lot of memory after running that search
operation a handful of times. It seems that the majority of the memory
allocation comes from the hasMoreElements() method of the enumeration
that I call within the while() mentioned above. I don't see any way of
not calling that method since I need it to grab the search results. The
question I have is why would the JVM use so much space for that method
and is there anything I can do to reclaim the memory? JProfiler says
that after a handful of search() executions there are over a million
allocations of hasMoreElements() that take up 50 megs. Jprofiler shows
garbage collections are occurring but since a method and not an Object
is taking up the memory I don't know how to fix this problem.

As a side note, if it was possible to properly cancel JNDI search
methods (from the InitialLdapContext class) then I wouldn't have such a
problem but once those searches start they can't be canceled from what I
can gather, despite utilizing threads.


Method calls don't explicitly allocate memory. I think you're
misinterpretting your profiler report.

Also, why not use ArrayList instead of Vector? Vector is outdated.

Other then that, I don't have any advice to give you, sorry.

In my opinion it is hard to interpret what I'm seeing any other way. In
case anyone is familiar with JProfiler, I'm on the Memory Views option,
on the Allocation Hot Spots tab within that view. The top hotspot is
"javax.naming.NamingEnumeration.hasMoreElements()" with allocated memory
of 47,997KB (92%) with 1,046,444 allocations. And that is using the
Aggregation Level of "methods". I'll look into the ArrayList but I'd
like to fix the current problem before jumping to something else.


To add to this, I downloaded a Java app that does the same job as my app
(just in a different way) and it runs into the same thing as my app
based on what the profiler says. The issue just isn't as pronounced.

"results" is a NamingEnumeration
"node" is the tree node that was selected to retrieve children for

while (results != null && results.hasMoreElements()) {
    SearchResult si = (SearchResult);
    TreeNode2 t = new TreeNode2( si.getName(),
    si.getName() + ", " + searchbase);
    n = (BasicAttribute)si.getAttributes().get("numsubordinates");

The profiler says that the method is a Memory allocation
hot spot that uses 15,370KB after 301,109 allocations. My program
actually has a hotspot on the results.hasMoreElements() method as I
mention above in a previous post.

If anyone has any suggestions as to what this means and if there is
anything I can do about it let me know.


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