ESP8266 NodeMCU Running Out of Heap Memory

Question

I am trying to toggle an LED using ESP8266-01 by sending POST from my laptop (using node.js)

I now have a memory issue because whenever I send POST request, the memo

Answer 1

So the solution from Marcel worked.

Here is just another option to solve the problem:

print("Starting main.lua... \n")
gpio.mode(3, gpio.OUTPUT)
srv=net.createServer(net.TCP,28800)
print("Server created... \n")
srv:listen(80,function(conn)
    conn:on("receive", function(conn,request)
        local _,_,method,path= string.find(request, "([A-Z]+) (.+)?(.+) HTTP")
        local _,_,key,light_level = string.find(request, "(%a+)%s*:%s*(%d+)")
        if(method == nil)then
            _,_,method,path = string.find(request, "([A-Z]+) (.+) HTTP")
        end
        local duty=light_level*1023/100
        pwm.setup(3, 500, duty)
        local message={}
        print("Level:"..light_level)
        if(method == "POST")then --light_level was sent from node.js as the header of the request
           if(duty>0)then
              pwm.start(3)
              message = {"HTTP/1.0 200 OK\r\n Content-Type: text/html\r\n\r\n"}
              message[#message + 1] = (light_level/100)
           elseif(duty==0)then
              pwm.stop(3)
              message = {"HTTP/1.0 200 OK\r\n Content-Type: text/html\r\n\r\n"}
              message[#message + 1] = 0
           end 
        elseif(method == "GET")then
           message[#message + 1] = "HTTP/1.1 200 OK\r\n Content-Type: text/html\r\n\r\n"
           message[#message + 1] = "LED STATE="..tostring(pinState).."\r\n"
        end
        local function send()
          if #message > 0 then 
             conn:send(table.remove(message, 1))
          else
             conn:close()
             conn = nil
             collectgarbage()
          end
        end
        conn:on("sent", send)
        send()
        local message = nil
        local _,_,method,path = nil
        local _,_,key,light_level = nil
        local duty=nil
        --for debugging
        local heapSize=node.heap()
        if heapSize<2000 then
           node.restart()
        end
        print("Memory Used:"..collectgarbage("count"))
        print("Heap Available:"..heapSize)
        local heapSize=nil
        --debugging end
    end)
end)