ajax - PHP: script executing twice -

i have php script processes xml file uploaded user . when file big (like 50mb) can take several minutes. on small files works how it's expected. faced 1 problem large ones.

so, file looks like:

if(file_exist($filename)) {     return array(false, "file name exist"); } else {     /*     processing of file     */      return array(true, "") } 

when user upload file javascript uploader, make ajax request script. , thing large file execute twice. first time go "processing" section, @ second time returns error file name exist (which true, actually).

i add logging function in beginning of script

$logger = zend_registry::get('logger'); $logger->log('assign file function called', 7); 

and see script has been called twice.

but in firebug see 1 ajax request script. in apache access.log see 1 request. apache error.log empty.

any idea can be? configuration long-time-executed scripts?

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upd javascript calling script

  $("#save_file_btn").click(function(){          var filename    =   $("input#selected_file").val();         if(!filename.length) {             customalert("choose file @ first");             return false;         }          $.ajax({             url: '/otms/publisher/assign-file-to-publisher',             beforesend: function(xhr){                 $("#add_form").html('<div class="loader"></div>');             },             datatype: 'json',             data: {filename: filename},             success: function(data) {                 if(data.success) {                     //process added onix file                     processonixfile(data.fileid, function(){                         getfilelist();                         $("#add_form").html('<div class="text-center">file has been uploaded</div>');                         settimeout('$("#add_file_modal").modal("hide")', 2500);                     });                 } else {                     var output = '';                     $.each(data.error, function(index,value){                         output += '<div class="bold">'+value.title+'</div>';                         output += '<ul>';                         $.each(value.errorlist, function(i, errormsg){                             output += '<li>'+errormsg+'</li>';                         });                         output += '</ul>';                     });                      $("#add_form").html('<div class="red">'+output+'</div>');                  }             }          });      }); 

i checked , place request made script 'assign-file-to-publisher' (where have problem).

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upd 2.

what found out script called twice in firefox browser. in safari request doesn't return anything. in chrome returns following status:

(failed) net::err_empty_response 

i still not see error messages in application logs or apache logs. mentioned script works big file , can take several minutes process it.

in configuration:

max_execution_time = 300 

while chrome return error on 1:40 time.