Hi,
Something in my program is eating up memory. I am running php 5 and
hooking into postgres8.3, but I don't think it is a database program.
The command in question works fine in psql, the problem comes in
loading a php variable. And in the past, unsetting the variable has helped.
The program itself is perhaps 1000 lines long, so I won't post it.
I tried to isolate the problem with this code:
require_once('/hdir/0/maryfran/unproto/memdev/config_file.php'); //
connects to database
require_once('/hdir/0/maryfran/unproto/memdev/DMEM_stuff.php'); //
has constants for app
function do_select_many($pg,
$select_cmd){
global $DMEM_ERROR, $DMEM_DEBUG;
@pg_connection_status($pg) === PGSQL_CONNECTION_OK
or die("Database connection bad.\n");
$sql_result = @pg_query($pg, $select_cmd);
if (pg_result_status($sql_result) != PGSQL_TUPLES_OK){
if ($DMEM_DEBUG){
echo pg_last_error($pg);
echo "\n<br>\n";
echo $select_cmd;
echo "\n<br>\n";
}
return array($DMEM_ERROR);
}
$values_hashed_by_column = pg_fetch_all($sql_result); ///WHERE
THE APPLICATION BOMBS
pg_free_result($sql_result);
return $values_hashed_by_column;
}
function fu_bar($pg, $sql_cmd){
$foo = do_select_many($pg,
$sql_cmd);
return($foo);
}
$BIG_SELECT_cmd = " SELECT value,
x.d8_dv_id,
x.dm2_dv_id,
x.dm1_dv_id,
x.d5_dv_id,
x.d7_dv_id,
x.xp_data_batch_id,
x.xp_sub_batch_id
FROM
display.tmp_xprod_table x LEFT JOIN display.tmp_data_values v
ON x.d8_dv_id = v.d8_dv_id
AND x.dm2_dv_id = v.dm2_dv_id
AND x.dm1_dv_id = v.dm1_dv_id
AND x.d5_dv_id = v.d5_dv_id
AND x.d7_dv_id = v.d7_dv_id
AND x.xp_data_batch_id = v.data_batch_id
AND x.xp_sub_batch_id = v.sub_batch_id
ORDER BY x.d8_value_rank,
x.dm2_value_rank,
x.dm1_value_rank,
x.d5_value_rank,
x.d7_value_rank,
x.xp_dmem_status,
x.xp_created_date ";
$many_selected = fu_bar($pg,
$BIG_SELECT_cmd);
// IF I RUN THIS THROUGH A LOOP:
// for($j=0;$j<20, $j++){ $many_selected[$jj] = fu_bar($pg,
$BIG_SELECT_cmd)} THE TEST PROGRAM CRASHES so I think I have
more copies of the result of this query than I need.
?>
<p> <?php echo_submit('push_my_button', "Push"); ?></p> //Code which
prints a submit button (<input type="submit">)
BIG_SELECT is the only command which pulls a significant amount of data
(40K to 2M) into the database. In the real application, executing the
function which runs this command results in an memory fault at the point
in do_select_many that I have indicated. However, this piece of test
code runs just fine! And the BIG_SELECT_cmd works just fine when cut
and pasted directly into psql. Sometimes, even the real application
will work just fine.
I am stymied. I can neither isolate the problem in a piece of test
code, nor can I reliably fix the problem when it occurs. Any help on
debuggers which will find memory leaks in php code, (Yeah. PHP 5.2 has
some!) or tricks of the trade in finding them, or tips on where to look
would be greatly appreciated.
At this point, I really do not know when and where php frees memory.
Let me be a little more specific:
1. Does passing a large array as a reference into or out of a
function save space?
2. Suppose I hit a submit button. Are all the variables on
the page still taking up space?
3. Any known bugs with pg_fetch_all running on 8.3? How do I
find them?
4. Suppose I follow a link. Do my variables on the old page
still take up space?
5. Should I be handling my arrays one chunk at a time?
6. When I exit a php function, isn't all the space used by
function variables freed?
7. Why would it sometimes work to clear the cache? This
problem seems to me to be an intermittent one.
8. Most important, what good programming practices should I be
following to keep this from happening?
Mary Anderson
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