Description:
------------
The essence of the problem is that when using the ZipArchive methods asynchronously, at the output I get the required archive, but only with the last processed file within the framework of asynchrony (To be more precise, the archive contains N / t files, where N is the total files to be added , t is the number of processing threads)
PS-The initial presence of the archive does not change the situation.

Example: (6 files)
https://drive.google.com/file/d/1BAHn4iSElaADwfxQ_3_ZaTOmPKvggwH6/view?usp=sharing

Test script:
---------------
//one stream
$za = new \ZipArchive();
 ($za->open($zipFile, \ZipArchive::CREATE) !== TRUE) {
      throw new \Exception('Cannot create a zip file');
 } 
$arFile = $dir . '/' . $newFileName . '.json';
$result = $za->addFromString($arFile, $stringData);
$error = $za->getStatusString( );
$arIndex = $za->locateName($arFile);
$arInfo = $za->statName($arFile);
$closeResult = $za->close();
 var_dump($error, $arIndex, $arInfo, $closeResult);

Expected result:
----------------
file2
file1
file3
file4
string(8) "No error"
int(0)
array(8) {
  ["name"]=>
  string(17) "/order/file2.json"
  ["index"]=>
  int(0)
  ["crc"]=>
  int(0)
  ["size"]=>
  int(811758)
  ["mtime"]=>
  int(1617821517)
  ["comp_size"]=>
  int(811758)
  ["comp_method"]=>
  int(0)
  ["encryption_method"]=>
  int(0)
}
bool(true)
string(8) "No error"
int(0)
array(8) {
  ["name"]=>
  string(17) "/order/file3.json"
  ["index"]=>
  int(0)
  ["crc"]=>
  int(0)
  ["size"]=>
  int(811758)
  ["mtime"]=>
  int(1617821517)                                                                                                                                                                                                  
  ["comp_size"]=>                                                                                                                                                                                                  
  int(811758)                                                                                                                                                                                                      
  ["comp_method"]=>                                                                                                                                                                                                
  int(0)                                                                                                                                                                                                           
  ["encryption_method"]=>                                                                                                                                                                                          
  int(0)                                                                                                                                                                                                           
}                                                                                                                                                                                                                  
bool(true)                                                                                                                                                                                                         
string(8) "No error"                                                                                                                                                                                               
int(0)                                                                                                                                                                                                             
array(8) {
  ["name"]=>
  string(17) "/order/file4.json"
  ["index"]=>
  int(0)
  ["crc"]=>
  int(0)
  ["size"]=>
  int(811758)
  ["mtime"]=>
  int(1617821517)
  ["comp_size"]=>
  int(811758)
  ["comp_method"]=>
  int(0)
  ["encryption_method"]=>
  int(0)
}
bool(true)
string(8) "No error"
int(0)
array(8) {
  ["name"]=>
  string(17) "/order/file1.json"
  ["index"]=>
  int(0)
  ["crc"]=>
  int(0)
  ["size"]=>
  int(811758)
  ["mtime"]=>
  int(1617821517)
  ["comp_size"]=>
  int(811758)
  ["comp_method"]=>
  int(0)
  ["encryption_method"]=>
  int(0)
}
bool(true)


Actual result:
--------------
4 JSON-files in ZIP-archive.