Code Crashing when Requesting Data from OpenWeatherMap

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Hello Everyone,
I am new to ESP32 and wanted to write a simple application to get weather information from the OpenWeatherMap website.
It works fine for the first time, but when I try to request the data next time, my program crashes and restarts with the following message.

Code: [Select all] [Expand/Collapse]

1. Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

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The following is the piece of the code for reference, and it is crashing when "openweathermap_send_request" is called second time, and more specifically while calling the function "esp_err_t err = esp_http_client_perform(client);"

Code: [Select all] [Expand/Collapse]

1. // OpenWeatherMap Task
2. static void openweathermap_task(void *pvParameters)
3. {
4.   // Initialize the City Names
5.   strcpy(city_weather[0].city_name, "manali");
6.   strcpy(city_weather[1].city_name, "kashmir");
7.   strcpy(city_weather[2].city_name, "jaipur");
8.   strcpy(city_weather[3].city_name, "delhi");
9.  
10.   for( ; ; )
11.   {
12.     openweathermap_send_request();
13.     vTaskDelay(HTTP_REQ_EXEC_RATE / portTICK_PERIOD_MS);
14.   }
15.  
16.   vTaskDelete(NULL);
17. }
18.  
19. static void openweathermap_send_request(void)
20. {
21.   char openweathermap_url[200];
22.   city_weather_index = 0;  // added for debugging
23.   snprintf( openweathermap_url, sizeof(openweathermap_url), \
24.             "%s%s%s", CLIENT_REQ_PRE, city_weather[city_weather_index].city_name, CLIENT_REQ_POST);
25.  
26.   esp_http_client_config_t config =
27.   {
28.     .url = openweathermap_url,
29.     .method = HTTP_METHOD_GET,
30.     .event_handler = openweathermap_event_handler,
31.   };
32.  
33.   ESP_LOGI(TAG, "OpenWeatherMap Task Execution Started");
34.  
35.   esp_http_client_handle_t client = esp_http_client_init(&config);
36.   esp_http_client_set_header(client, CLIENT_KEY, CLIENT_VALUE);
37.   esp_err_t err = esp_http_client_perform(client);
38.   if( err == ESP_OK )
39.   {
40.     int status = esp_http_client_get_status_code(client);
41.     if(status == 200)
42.     {
43.       ESP_LOGI(TAG, "City=%s, Message Sent Successfully", city_weather[city_weather_index].city_name);
44.       city_weather_index++;
45.       // Reset back to Initial Position
46.       if( city_weather_index >= NUM_OF_CITIES )
47.       {
48.         city_weather_index = 0;
49.       }
50.     }
51.     else
52.     {
53.       ESP_LOGI(TAG, "City=%s, Message Sent Failed", city_weather[city_weather_index].city_name);
54.     }
55.   }
56.   else
57.   {
58.     ESP_LOGI(TAG, "City=%s, Message Sent Failed", city_weather[city_weather_index].city_name);
59.   }
60.   esp_http_client_cleanup(client);
61.   ESP_LOGI(TAG, "OpenWeatherMap Task Execution Complete");
62. }
63.  
64. static esp_err_t openweathermap_event_handler(esp_http_client_event_t *event)
65. {
66.   switch(event->event_id)
67.   {
68.     case HTTP_EVENT_ON_DATA:
69.       // Resize the Buffer to fit the new chunk of the data
70.       response_data = realloc(response_data, response_len + event->data_len);
71.       // Copy the Data
72.       memcpy(response_data+response_len, event->data, event->data_len);
73.       // Update the Length
74.       response_len += event->data_len;
75.       // Only used for debugging
76.       // ESP_LOGI("OpenWeatherAPI", "Partial Received Data: %d", event->data_len);
77.       break;
78.     case HTTP_EVENT_ON_FINISH:
79.       all_data_received = true;
80.       // NOTE: TAG is different here (debugging purpose)
81.       // ESP_LOGI("OpenWeatherAPI", "Received Data: %s", response_data);
82.       // Decode/Parse the weather data from the response data
83.       openweathermap_get_weather(response_data, &city_weather[0]);
84.       // free up the space, and reset the response length
85.       free(response_data);
86.       response_len = 0;
87.       ESP_LOGI("OpenWeatherAPI", "City=%s, Temp=%f, Pressure=%d, Humidity=%d", \
88.                 city_weather[city_weather_index].city_name,   \
89.                 city_weather[city_weather_index].temperature, \
90.                 city_weather[city_weather_index].pressure,    \
91.                 city_weather[city_weather_index].humidity);
92.       ESP_LOGI("OpenWeatherAPI", "Exiting Event Handler");
93.       break;
94.     default:
95.       break;
96.   }
97.   return ESP_OK;
98. }

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Logs on Terminal when code crashed.

Code: [Select all] [Expand/Collapse]

1. I (27940) WIFI: OpenWeatherMap Task Execution Complete
2. I (30920) WIFI: Hello World from Main Task
3. I (32940) WIFI: OpenWeatherMap Task Execution Started
4. I (35920) WIFI: Hello World from Main Task
5. I (35970) OpenWeatherAPI: City=manali, Temp=30.040001, Pressure=1007, Humidity=82
6. I (35970) OpenWeatherAPI: Exiting Event Handler
7. I (35970) WIFI: City=manali, Message Sent Successfully
8. I (35980) WIFI: OpenWeatherMap Task Execution Complete
9. I (40920) WIFI: Hello World from Main Task
10. I (40980) WIFI: OpenWeatherMap Task Execution Started
11. Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

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Any sort of help is appreciated.
Thanks, and Regards

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I found the reason, it was not due to the "_perform()" function, while it was due to the realloc function, still don't know why, instead of crashing it should have returned the NULL pointer.
Anyways I changed the approach to use a big buffer and track the data with indexes, and it works.
The problem is solved, in case someone wanted to comment on something, feel free.
Thanks, and Regards