Server.avaiable() randomly stalls the MCU for X-seconds

[RayanR]

when connecting top the server using a browser, it works fine untill it suddenly grinds to a halt and stops updating. After some searching, it seems the server halts for a while and then it starts running again. This behaviour results in lots of timeout errors

`
byte mac[] = {0x04, 0xe9, 0xe5, 0x0d, 0xd6, 0x4b};
IPAddress ip(10, 116, 114, 134); // IP address, may need to change depending on network

EthernetServer server(80); // create a server at port 80
EthernetClient client;
char HTTP_req[REQ_BUF_SZ] = {0}; // buffered HTTP request stored as null terminated string
char req_index = 0; // index into HTTP_req buffer
uint32_t ethping = 0;
String loc = "loop";

void ethernet_init() {
// start the Ethernet connection and the server:
Ethernet.begin(mac); // DHCP
//Ethernet.begin(mac,ip); // Static IP

// Check for Ethernet hardware present
if (Ethernet.hardwareStatus() == EthernetNoHardware) {
if (Serial)Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
error_blink(ETHERNET_NO_HARDWARE);
do {
if (Serial)Serial.println("Please connect Ethernet shield");
error_blink();// do nothing, no point running without Ethernet hardware
}
while (Ethernet.hardwareStatus() == EthernetNoHardware);
error_blink(PULSE);
}
if (Ethernet.linkStatus() != LinkON) {
if (Serial)Serial.println("Ethernet cable is not connected.");
error_blink(ETHERNET_NO_CABLE);
do {
if (Serial)Serial.println("Please connect Ethernet cable");
error_blink();// do nothing, no point running without Ethernet cable
}
while (Ethernet.hardwareStatus() == LinkOFF);
error_blink(PULSE);
}

// start the server
server.begin();
if (Serial) {
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
}

void ethernet_client() {
client = server.available(); // try to get client

if (client) { // got client?
boolean currentLineIsBlank = true;
if (Serial) Serial.println("Client");
while (client.connected()) {
loc = "ethc";
can0.events();
error_blink();
if (client.available()) { // client data available to read
char c = client.read(); // read 1 byte (character) from client
// limit the size of the stored received HTTP request
// buffer first part of HTTP request in HTTP_req array (string)
// leave last element in array as 0 to null terminate string (REQ_BUF_SZ - 1)
if (req_index < (REQ_BUF_SZ - 1)) {
HTTP_req[req_index] = c; // save HTTP request character
req_index++;
}
// last line of client request is blank and ends with \n
// respond to client only after last line received
if (c == '\n' && currentLineIsBlank) {
if (Serial) Serial.println("XML request");
loc = "ethx";
// send a standard http response header
client.println("HTTP/1.1 200 OK");
// remainder of header follows below, depending on if
// web page or XML page is requested
// Ajax request - send XML file
if (strstr(HTTP_req, "HVPC_inputs")) {
// send rest of HTTP header
client.println("Content-Type: text/xml");
client.println("Connection: keep-alive");
client.println();
Settings();
// send XML file containing input states
XML_response(client);
}
else { // web page request
if (Serial) Serial.println("Page request");
// send rest of HTTP header
client.println("Content-Type: text/html");
client.println("Connection: keep-alive");
client.println();
// send web page
File webFile = SD.open("index.htm"); // open web page file
if (webFile) {
error_blink(SENDING_FILE);
loc = "ethf";
char file_buffer[ETH_BUFFER_SIZE];
int avail;
while (avail = webFile.available()) {
int to_read = min(avail, ETH_BUFFER_SIZE);
if (to_read != webFile.read(file_buffer, to_read)) {
break;
}
client.write(file_buffer, to_read);
}
webFile.close();
error_blink(PULSE);
}
}
// display received HTTP request on serial port
if (Serial) Serial.println(HTTP_req);
// reset buffer index and all buffer elements to 0
req_index = 0;
StrClear(HTTP_req, REQ_BUF_SZ);
if (Serial) Serial.println("cleared");
break;
}
// every line of text received from the client ends with \r\n
if (c == '\n') {
// last character on line of received text
// starting new line with next character read
currentLineIsBlank = true;
}
else if (c != '\r') {
// a text character was received from client
currentLineIsBlank = false;
}
} // end if (client.available())
} // end while (client.connected())
delay(1); // give the web browser time to receive the data
client.stop(); // close the connection
client = 0;
Ethernet.maintain();
if (Serial)
{
Serial.println("Client stopped");
Serial.println();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
}
}
`