Php out of memory

Question

I've got a memory problem which shows up in php like:
unable to allocate memory for mutex; resize mutex region
I have implemented a query almost exactly like the query in
the Berkeley DB XML book, page 184. I do a query, then
create a prepared query to further refine the result. In my case, the
outside where looks like:
fn:collection("$z")/dataset[@name="$dsn"]/qualification
Which returns thousands of things that look like this:
<qualification>
<arg name="queryname" value="getnewdataset"/>
<arg name="fromtimestamp" value="2009-09-07T21:00:00-05:00"/>
<arg name="totimestamp" value="2009-09-07T22:00:00-05:00"/>
<arg name="dtype" value="U"/>
</qualification>
<qualification>
<arg name="queryname" value="getnewdataset"/>
<arg name="fromtimestamp" value="2009-09-07T22:00:00-05:00"/>
<arg name="totimestamp" value="2009-09-07T23:00:00-05:00"/>
<arg name="dtype" value="U"/>
</qualification>
I prepare this query once:
$pqc->setVariableValue("attname", "fromtimestamp");
$pq = $mgr->prepare('arg[@name=$attname]/@value', $pqc);
Then, for each result, execute the prepared query:
try
$pqc->setVariableValue($column_name, $colval);
$ts = $pq->execute($res, $pqc);
while($ts->hasNext())
$v .= $ts->next()->asString();
catch(Exception $e)
print "got exception " . $e->getMessage();
exit(0);
Every time I run it I get the exception (after 636 successful executions) :
unable to allocate memory for mutex; resize mutex region
Any ideas? I am using this technique as a 'bind' to connect
php variables to bdb xml return values. Is there a better way?
I can use the php xml dom, or I could parse the <qualification> subtree
that comes back as a string. What is the preferred way of moving data in to
program variables?
-g

Answer 1

Some more information. The contexts that I was using for the inside and
outside queries were 'Eager'. I changed to 'Lazy' and the query works. I then
changed just the outside query to 'Lazy' and the inside to 'Eager' and it works.
It's just when the outside query is 'Eager' that the failure occurs.
-g