[Xapian-discuss] PHP Bindings... Infinite Loop?

[Ryan Mahoney]

Hi Olly, thanks for the detailed response.  I am going to make all of 
the changes you have recommended.

The immediate cause of the problem was that I was using the php dl() 
function to load the xapian.so file.  In previous versions this was 
working well for me.  Once I took out this code and put the extension in 
the php.ini file, the problem went away!

Keep up the great work,

-r


Olly Betts wrote:
> On Wed, Dec 27, 2006 at 02:48:50PM -0500, Ryan Mahoney wrote:
>   
>> I recently upgraded to version 0.9.9 of the php bindings.  I am running 
>> Apache 2.2.3 and PHP 5.2.  I have re-indexed all my data with the latest 
>> version of scriptindex.  The data set I have is somewhat small, maybe 
>> 4000 items.  When I run a query, it completes quickly, but as I run a 
>> few more (maybe 2 or 3), the Apache process goes out of control, using 
>> up 1 CPU completely on a 4 CPU linux server.  Any ideas?
>>     
>
> I notice you're using the now-deprecated flat function interface.  I
> guess that could be the problem.  Even if it isn't, updating is a good
> idea:
>
> http://article.gmane.org/gmane.comp.search.xapian.general/3754
>
> As for the loop, the thing you need to do is narrow down where it is
> looping.  You can attach gdb to an existing process with pid PID using
> "gdb --pid PID" and then type "bt" to produce a backtrace from the
> current point of execution.  This will only help if the problem is
> in code compiled with debugging, otherwise you won't get a very helpful
> answer.
>
> Other than that, I'd suggest the tried and tested debugging technique
> of adding `print "got to 1\n";', `print "got to 2\n";', etc through the
> code to at least find out where in the PHP script it starts looping.
>
>   
>>                //create a query parser
>>                define('FLAG_BOOLEAN', 1);
>>     
>
> You should use the constants defined by the xapian bindings rather than
> defining them for yourself - the numerical values aren't guaranteed to
> remain the same when the library ABI changes, but the named constants
> will.  With the deprecated flat wrappers, you should be using
> QueryParser_FLAG_BOOLEAN (with the OO wrappers for PHP5, it's
> XapianQueryParser::FLAG_BOOLEAN).
>
>   
>>                $query_parser = new_queryparser();
>>
>>                //set the stemmer and turn on the stemming strategy
>>                queryparser_set_stemmer($query_parser, $stemmer);
>>                queryparser_set_stemming_strategy($query_parser, 1);
>>     
>
> Similar issue - use the named constant (QueryParser_STEM_SOME or
> XapianQueryParser::STEM_SOME), not a literal numerical value!
>
>   
>>                //count elements in each category
>>                foreach($category as $cat_id => $cat_name) {
>>     
>
> You don't appear to have posted a complete example here.  If you have
> then $category is undefined at this point.
>
>   
>>                        $cat_enq = new_enquire($db);
>>     
>
> You might as well just reuse a single XapianEnquire object here.
>
>   
>>                        //parse and create the query
>>                        $cat_query = 
>> queryparser_parse_query($query_parser, $_REQUEST["search"] . " 
>> category:" . $cat_id);
>>     
>
> You shouldn't abuse the QueryParser like this.  Only use it for human
> entered queries.  If you want to apply an automatic filter to a human
> entered query, do something like:
>
>     $query = $query_parser->parse_query($_REQUEST["search"]);
>     $query = new XapianQuery(XapianQuery::OP_FILTER, $query, new XapianQuery("XC" + $cat_id));
>
> Trying to modify the user's query opens a big can of worms - for
> example, they might enter `foo NOT' as the query, and your filter will
> get applied inverted: `foo NOT category:bar'
>
> A bonus in this case is that you can parse the user's query just once
> outside the loop, and combined it with each filter in turn inside the
> loop.
>
>   
>>                $query = queryparser_parse_query($query_parser, 
>> $_REQUEST["search"] . $append);
>>     
>
> Same issues here.
>
>   
>>                $item = mset_begin($result_set);
>>                $total = mset_get_matches_estimated($result_set);
>>
>>                $pages = ceil($total / $results_per_page);
>>
>>                //reset array
>>                $item = mset_begin($result_set);
>>     
>
> I don't understand what "reset array" means here.  Calling mset_begin
> twice like this is pointless since you don't touch $item from the first
> call.  Should be harmless though, it's just wasted effort.
>
> Cheers,
>     Olly
>
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