doubt with memory when using esp_http_client

[jakarman12]

Hello guys,

I have a doubt with the handling of the heap when using esp_http_client.

Every time I make a new request, the heap decreases (I attach the image) after several requests the heap remains at a static value (red box in the image), this last value is what I would expect since I am making the same request with a very similar answer.

What is the reason that when making a new request the heap decreases?

I already checked and I don't have any malloc without free() ... is there a reason for this to happen?

I am relying on the example of esp_http_client... I attach my code

esp-idf: v4.3-dev-2586-g526f68239

Code: [Select all] [Expand/Collapse]

1. #include <string.h>
2. #include <stdlib.h>
3. #include "freertos/FreeRTOS.h"
4. #include "freertos/task.h"
5. #include "esp_log.h"
6. #include "esp_system.h"
7. #include "nvs_flash.h"
8. #include "esp_event.h"
9. #include "esp_netif.h"
10. #include "protocol_examples_common.h"
11. #include "esp_tls.h"
12. #include "esp_http_client.h"
13.  
14. #define MAX_HTTP_RECV_BUFFER 512
15. #define MAX_HTTP_OUTPUT_BUFFER 2048
16. static const char *TAG = "HTTP_CLIENT";
17.  
18. esp_err_t _http_event_handler(esp_http_client_event_t *evt)
19. {
20.     static char *output_buffer;  // Buffer to store response of http request from event handler
21.     static int output_len;       // Stores number of bytes read
22.     switch(evt->event_id) {
23.         case HTTP_EVENT_ERROR:
24.             ESP_LOGD(TAG, "HTTP_EVENT_ERROR");
25.             break;
26.         case HTTP_EVENT_ON_CONNECTED:
27.             ESP_LOGD(TAG, "HTTP_EVENT_ON_CONNECTED");
28.             break;
29.         case HTTP_EVENT_HEADER_SENT:
30.             ESP_LOGD(TAG, "HTTP_EVENT_HEADER_SENT");
31.             break;
32.         case HTTP_EVENT_ON_HEADER:
33.             ESP_LOGD(TAG, "HTTP_EVENT_ON_HEADER, key=%s, value=%s", evt->header_key, evt->header_value);
34.             break;
35.         case HTTP_EVENT_ON_DATA:
36.             ESP_LOGD(TAG, "HTTP_EVENT_ON_DATA, len=%d", evt->data_len);
37.             /*
38.              *  Check for chunked encoding is added as the URL for chunked encoding used in this example returns binary data.
39.              *  However, event handler can also be used in case chunked encoding is used.
40.              */
41.             if (!esp_http_client_is_chunked_response(evt->client)) {
42.                 // If user_data buffer is configured, copy the response into the buffer
43.                 if (evt->user_data) {
44.                     memcpy(evt->user_data + output_len, evt->data, evt->data_len);
45.                 } else {
46.                     if (output_buffer == NULL) {
47.                         output_buffer = (char *) malloc(esp_http_client_get_content_length(evt->client));
48.                         output_len = 0;
49.                         if (output_buffer == NULL) {
50.                             ESP_LOGE(TAG, "Failed to allocate memory for output buffer");
51.                             return ESP_FAIL;
52.                         }
53.                     }
54.                     memcpy(output_buffer + output_len, evt->data, evt->data_len);
55.                 }
56.                 output_len += evt->data_len;
57.             }
58.  
59.             break;
60.         case HTTP_EVENT_ON_FINISH:
61.             ESP_LOGD(TAG, "HTTP_EVENT_ON_FINISH");
62.             if (output_buffer != NULL) {
63.                 // Response is accumulated in output_buffer. Uncomment the below line to print the accumulated response
64.                 // ESP_LOG_BUFFER_HEX(TAG, output_buffer, output_len);
65.                 free(output_buffer);
66.                 output_buffer = NULL;
67.             }
68.             output_len = 0;
69.             break;
70.         case HTTP_EVENT_DISCONNECTED:
71.             ESP_LOGI(TAG, "HTTP_EVENT_DISCONNECTED");
72.             int mbedtls_err = 0;
73.             esp_err_t err = esp_tls_get_and_clear_last_error(evt->data, &mbedtls_err, NULL);
74.             if (err != 0) {
75.                 if (output_buffer != NULL) {
76.                     free(output_buffer);
77.                     output_buffer = NULL;
78.                 }
79.                 output_len = 0;
80.                 ESP_LOGI(TAG, "Last esp error code: 0x%x", err);
81.                 ESP_LOGI(TAG, "Last mbedtls failure: 0x%x", mbedtls_err);
82.             }
83.             break;
84.     }
85.     return ESP_OK;
86. }
87.  
88. static void http_rest_with_url(void)
89. {
90.     char local_response_buffer[MAX_HTTP_OUTPUT_BUFFER] = {0};
91.  
92.     esp_http_client_config_t config = {
93.         .host = "httpbin.org",
94.         .path = "/get",
95.         .query = "esp",
96.         .event_handler = _http_event_handler,
97.         .user_data = local_response_buffer,        // Pass address of local buffer to get response
98.         .disable_auto_redirect = true,
99.     };
100.     esp_http_client_handle_t client = esp_http_client_init(&config);
101.  
102.     // GET
103.     esp_err_t err = esp_http_client_perform(client);
104.     if (err == ESP_OK) {
105.         ESP_LOGI(TAG, "HTTP GET Status = %d, content_length = %d",
106.                 esp_http_client_get_status_code(client),
107.                 esp_http_client_get_content_length(client));
108.     } else {
109.         ESP_LOGE(TAG, "HTTP GET request failed: %s", esp_err_to_name(err));
110.     }
111.  
112.     esp_http_client_cleanup(client);
113. }
114.  
115. static void http_test_task(void *pvParameters)
116. {
117.     while (1)
118.     {
119.         vTaskDelay(5000 / portTICK_PERIOD_MS);
120.         http_rest_with_url();
121.         printf("Heap %d \r\n", esp_get_free_heap_size());
122.     }
123.  
124.     vTaskDelete(NULL);
125. }
126.  
127. void app_main(void)
128. {
129.     esp_err_t ret = nvs_flash_init();
130.     if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND)
131.     {
132.         ESP_ERROR_CHECK(nvs_flash_erase());
133.         ret = nvs_flash_init();
134.     }
135.     ESP_ERROR_CHECK(ret);
136.     ESP_ERROR_CHECK(esp_netif_init());
137.     ESP_ERROR_CHECK(esp_event_loop_create_default());
138.  
139.     ESP_ERROR_CHECK(example_connect());
140.     ESP_LOGI(TAG, "Connected to AP, begin http example");
141.  
142.     xTaskCreate(&http_test_task, "http_test_task", 8192, NULL, 5, NULL);
143. }
144.  

GeSHi © Codebox Plus Extension

[boarchuz]

Don't dwell on it, there's no leak if there's not a consistent pattern of reduction.

See this post: viewtopic.php?t=14056#p55646

And also consider that there are other tasks doing work behind the scenes - especially WiFi/lwip in this case, which will be dynamically allocating/deallocating buffers as required.