将新值推送到mongodb不能在PHP中运行多进程

I'm coding a testing program: 200 processes write 10000 records to one collection in mongodb The record should be appended to the end of the collection, so I follow the example [push new value to mongodb inner array][1] - mongodb/php

below is my code:

$data = $memcache->get('data');
$m = new MongoClient();
$db = $m->record_test;
$collection = $db->record;
$time = $db->record_time;

for ($i=0; $i < 10000; $i++) { 
    $time_start = microtime_float();

    $collection->insert($data);

    $time_end = microtime_float();
    $run_time = $time_end - $time_start;

    $newdata = array('$push' => array('time' => $run_time));
    $time->update(array("time" => 0 ), $newdata);
}

$data's content: Array ( [0] => Array ( [Register_Name] => MGC_IP [Register_Value] => 192.168.1.9 [Register_Unit] => [Device_Name] => this [R_W] => )

[1] => Array
    (
        [Register_Name] => MGC_SW_VERSION
        [Register_Value] => 0.9.15.1022_SPI  
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[2] => Array
    (
        [Register_Name] => MGC_FW_VERSION
        [Register_Value] => 0.1.15.915.1     
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[3] => Array
    (
        [Register_Name] => MGC_ZONE_ID
        [Register_Value] => zone0    
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[4] => Array
    (
        [Register_Name] => MGC_DEVICE_ID
        [Register_Value] => mgc0     
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[5] => Array
    (
        [Register_Name] => MGC_SYS_TIME
        [Register_Value] => 2015/10/27 10:12:04  
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[6] => Array
    (
        [Register_Name] => MGC_P1_STATUS
        [Register_Value] => Access fails     
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

[7] => Array
    (
        [Register_Name] => MGC_P2_STATUS
        [Register_Value] => Not configured   
        [Register_Unit] =>  
        [Device_Name] => this
        [R_W] =>  R
    )

)

After 10000 records has be done, I got nothing in the collection! I used this sample code to check my result:

$m = new MongoClient();
echo "Connection to database successfully.<br>";
$db = $m->record_test;
echo "Database record_test selected.<br>";
$time = $db->record_time;
echo "Collection record selected succsessfully.<br>";
echo $time->count(), "
";

$cursor = $time->find();
var_dump(iterator_to_array($cursor));

Output:

Connection to database successfully.
Database record_test selected.
Collection record selected succsessfully.
0

Could someone help me? Why my var_dump() nothing? I'm really new in mongodb and PHP :'(