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Thread: TeensyThreads / Webserver Responsetime

  1. #1
    Junior Member
    Join Date
    Apr 2021

    TeensyThreads / Webserver Responsetime


    I'm using a Teensy 4.1 with the nativ ethernet and trying to run a webserver with TeensyThreads.
    There is the problem that the response time is very different.
    I get a response between 0.03 seconds and 5 seconds.
    Everything is connected with network cable, no wifi.


      Web Server
     A simple web server that shows the value of the analog input pins.
     using an Arduino Wiznet Ethernet shield.
     * Ethernet shield attached to pins 10, 11, 12, 13
     * Analog inputs attached to pins A0 through A5 (optional)
     created 18 Dec 2009
     by David A. Mellis
     modified 9 Apr 2012
     by Tom Igoe
     modified 02 Sept 2015
     by Arturo Guadalupi
    #include <SPI.h>
    #include <NativeEthernet.h>
    #include <TeensyThreads.h>
    // Enter a MAC address and IP address for your controller below.
    // The IP address will be dependent on your local network:
    byte mac[] = {
      0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
    IPAddress ip(192, 168, 2, 161);
    // Initialize the Ethernet server library
    // with the IP address and port you want to use
    // (port 80 is default for HTTP):
    EthernetServer server(80);
    void setup() {
      // You can use Ethernet.init(pin) to configure the CS pin
      //Ethernet.init(10);  // Most Arduino shields
      //Ethernet.init(5);   // MKR ETH shield
      //Ethernet.init(0);   // Teensy 2.0
      //Ethernet.init(20);  // Teensy++ 2.0
      //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
      //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet
      // Open serial communications and wait for port to open:
      while (!Serial) {
        ; // wait for serial port to connect. Needed for native USB port only
      Serial.println("Ethernet WebServer Example");
      // start the Ethernet connection and the server:
      Ethernet.begin(mac, ip);
      // Check for Ethernet hardware present
      if (Ethernet.hardwareStatus() == EthernetNoHardware) {
        Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
        while (true) {
          delay(1); // do nothing, no point running without Ethernet hardware
      if (Ethernet.linkStatus() == LinkOFF) {
        Serial.println("Ethernet cable is not connected.");
      // start the server
      Serial.print("server is at ");
      std::thread first(loopWeb, 1);
    void loop() {
    void loopWeb()
        while (1)
        // listen for incoming clients
        EthernetClient client = server.available();
        if (client) {
          Serial.println("new client");
          // an http request ends with a blank line
          boolean currentLineIsBlank = true;
          while (client.connected()) {
            if (client.available()) {
              char c =;
              // if you've gotten to the end of the line (received a newline
              // character) and the line is blank, the http request has ended,
              // so you can send a reply
              if (c == '\n' && currentLineIsBlank) {
                // send a standard http response header
                client.println("HTTP/1.1 200 OK");
                client.println("Content-Type: text/html");
                client.println("Connection: close");  // the connection will be closed after completion of the response
                client.println("Refresh: 5");  // refresh the page automatically every 5 sec
                client.println("<!DOCTYPE HTML>");
                // output the value of each analog input pin
                for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
                  int sensorReading = analogRead(analogChannel);
                  client.print("analog input ");
                  client.print(" is ");
                  client.println("<br />");
              if (c == '\n') {
                // you're starting a new line
                currentLineIsBlank = true;
              } else if (c != '\r') {
                // you've gotten a character on the current line
                currentLineIsBlank = false;
          // give the web browser time to receive the data
          // close the connection:
          Serial.println("client disconnected");
    For the connection test I used curl:
    time curl -v --header "Content-Type: text/plain" --header "Accept: application/json" ""
    If I use it without threads, then the response time is always <0,05 seconds.
    Does anyone have an idea what I am doing wrong?

  2. #2
    Senior Member vjmuzik's Avatar
    Join Date
    Apr 2017
    For one, this version of NativeEthernet is not really thread safe so I can’t attest to the stability. Before I made NativeEthernet I was using FNET in a thread safe manner and I don’t remember ever having delays of any significance. If anything it’s probably that it’s not thread safe right now that’s causing the issue.

  3. #3
    Junior Member
    Join Date
    Apr 2021
    Thanks for the answer.
    Sorry if it's a stupid question, I'm a newbie.
    Is thread-safe not when multiple threads execute the same code?
    Here the code is executed only once but in a different thread?

    I used the Teensythread Test example and there I got this:

    CPU speed consistency ***FAIL***
    Test thread start OK
    Test thread run state OK
    Test thread return OK
    Test thread speed ***FAIL***
    Speed no threads: 64318116
    Speed 1 thread: 45516065
    Ratio: 0.71
    Test set time slice OK
    Speed default ticks: 45516174
    Speed 200 ticks: 86087821
    Expected: 86697480.00
    Ratio with expected: 0.99
    Test delay yield OK
    Yield wait ratio: 1.40
    Test thread end state OK
    Test thread reinitialize OK
    Test stack usage OK
    Test thread suspend OK
    Test thread restart OK
    Test thread stop OK
    Test thread start OK
    Test thread wait OK
    Test thread wait time OK
    Test thread kill OK
    Test std::thread scope OK
    Test basic lock OK
    Test basic unlock OK
    Test mutex lock state OK
    Test mutex lock thread OK
    Test mutex unlock OK
    Test fast locks OK
    18450000 18750000 16359966
    Test std::mutex lock OK
    Test std::mutex unlock OK
    Test Grab init OK
    Test Grab set OK
    Test Grab lock OK
    Test thread stack overflow OK
    Test infinite loop (will not end)
    0: 0 sec 56400898 440313259 13193278
    1: 5 sec 56400898 627492009 13193278
    2: 10 sec 56400898 815495335 13193278
    3: 15 sec 56400898 1002674085 13193278
    If I understand correctly, this reflects my problem.
    The thread "CPU speed consistency ***FAIL***" and "Test thread speed ***FAIL***" fails.

    Can it be that the thread library has something or my teensy4.1@ 450MHz?
    I'am use arduino 1.8.15 / teensyduino 1.54


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