STM32F4. Read data from UART. ERROR: Out of Memory!

Hi, Gordon, Hi all!
Working with the board STM32F4.
I have a problem when I try to transfer file from PC to UART (pins PA2, PA3).
If the file size small (less 200 bytes) all is well.
If the file size a bit more, then sometimes console shows the error memory.
If the file size like 2000 bytes, then always console shows the error memory.

I try change baudrate of UART from 9600 to 115200, and have a successful file transfer size in 2 528 bytes. But after a few hours situation with the problem persists.
STM32F4 has a lot of memory. Why this error occurs?

My project:

var LED_ORANGE = LED1;
var LED_GREEN  = LED2;
var LED_RED    = LED3;
var LED_BLUE   = LED4;
var arr = null;


function Toggle_Led(LED) {
 on = !on;
 digitalWrite(LED, on);
 return 1;
}

function Show(str) {
  console.log('**' + str);
}

function Thread1() {
  Toggle_Led(LED_ORANGE);

}

var Counter = 0;
Show("Start!");


// Тест UART
//==================================================================
Serial2.setup(9600, {rx:A3,tx:A2});
//USB.setup(9600, {dm:A11,dp:A12});
Serial2.on('data', function (data) {  // Receive function
  console.log(Counter + ") send");
  process.memory();
  if (data.length > 0) {  
    digitalWrite(LED_GREEN, 1);
    //console.log(data + "\n");
    
    if (arr == null)  {
      arr = new Array();
    }
    arr.push(data);          // Add new element

    // Таймаут приёма
    //==============================================================
    setTimeout(function (e) {
      if (arr == null)  return;
      //for (var i=0; i<arr.length; i++)
      //{
      //  console.log(arr[i]);
      //}
      var str = arr.join("");
      console.log(str);
      
      arr = null;
      Serial2.println(str);        // Send
      
      digitalWrite(LED_GREEN, 0);
      digitalWrite(LED_RED, 0);
    }, 5000);
    //==============================================================
  } else {
    digitalWrite(LED_RED, 1);
    console.log("Bad");
  }
  
  Counter++;
});
//==================================================================



setInterval(Thread1,3000);
Show("Stop!");
save();

My File:
{

"crosstime": {
    "1": [
        1, 
        10, 
        3, 
        3
    ], 
    "2": [
        1, 
        10, 
        3, 
        3
    ], 
    "3": [
        1, 
        20, 
        3, 
        1
    ]
}, 
"racks": {
    "1": {
        "1": 1, 
        "2": 1, 
        "3": 0, 
        "4": 0, 
        "5": 5, 
        "6": 5
    }, 
    "2": {
        "1": 2, 
        "2": 2, 
        "3": 0, 
        "4": 0, 
        "5": 5, 
        "6": 5
    }, 
    "3": {
        "1": 1, 
        "2": 1, 
        "3": 0, 
        "4": 0, 
        "5": 5, 
        "6": 5
    }, 
    "4": {
        "1": 2, 
        "2": 2, 
        "3": 0, 
        "4": 0, 
        "5": 5, 
        "6": 5
    }
}, 
"groups": {
    "1": {
        "1": [
            1, 
            3, 
            4, 
            5
        ], 
        "2": [
            2, 
            2, 
            2, 
            2
        ], 
        "3": [
            2, 
            2, 
            2, 
            2
        ]
    }, 
    "2": {
        "1": [
            2, 
            2, 
            2, 
            2
        ], 
        "2": [
            1, 
            3, 
            4, 
            5
        ], 
        "3": [
            2, 
            2, 
            2, 
            2
        ]
    }, 
    "3": {
        "1": [
            2, 
            2, 
            2, 
            2
        ], 
        "2": [
            2, 
            2, 
            2, 
            2
        ], 
        "3": [
            2, 
            3, 
            4, 
            2
        ]
    }
}, 
"desc": {
    "note": "\u041f\u0440\u043e\u0441\u0442\u0435\u0439\u0448\u0438\u0439 \u0441\u0432\u0435\u0442\u043e\u0444\u043e\u0440 \u0438\u0437 3 \u0433\u0440\u0443\u043f\u043f \u0438 3 \u0444\u0430\u0437.", 
    "phases": "3", 
    "name": "\u0422\u0435\u0441\u0442", 
    "groups": "3", 
    "addr": "\u0421\u0442\u0435\u043d\u0434"
}

}