as others have already said, run your code with valgrind, it is the tool to find memory leaks. If valgrind is too intrusive then run with the sanitizer in gcc or clang which have a much less runtime overhead (the benefit of valgrind is that it will find memory overwrites that gcc/clang will not).
top is not a great tool to use to measure leaks, memory is not automatically handed back by libc to the kernel when you call free() so the counters in applications like top only gives a very rough estimate. /HH Den tors 12 mars 2026 kl 19:44 skrev Sasmit Utkarsh via curl-library < [email protected]>: > Hi Team, > > I'm trying to write a program which uses which uses in libcurl handles in > multithreaded manner. i.e transfer/make a http post request every 10 secs > using the libh2o event-loop powered by libuv worker threads. But what i see > is when I clear the handle once done with the request. I see that memory > footprint of the process increases in top. is there any better approach > sharing the sample code for review > > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <stdbool.h> > #include <time.h> > > #include <curl/curl.h> > #include <uv.h> > #include <jansson.h> > > #include "sr71_logging.h" > #include "metrics_common.h" > #include "atomic_common.h" > > /* ============================================================ > GLOBAL STATE > ============================================================ */ > > bool metrics_publish = false; > > int stats_interval = 5000; > char opt_metrics_endp[512] = {0}; > static sr71_timer_callback stats_timer_handler; > > /* single-flight guards */ > > static int metrics_work_in_progress = 0; > static int token_refresh_in_progress = 0; > > /* shared OAuth token cache */ > > static char *metrics_token = NULL; > static long metrics_token_expiry = 0; > > static uv_timer_t *metrics_timer = NULL; > static uv_timer_t *midnight_timer = NULL; > static uv_timer_t *third_timer = NULL; > > /* ============================================================ > THREAD LOCAL CURL STATE > ============================================================ */ > > static __thread CURL *curl_auth = NULL; > static __thread CURL *curl_metrics = NULL; > > static __thread struct curl_slist *headers_auth = NULL; > static __thread struct curl_slist *headers_metrics = NULL; > > /* ============================================================ > CURL GLOBAL INIT > ============================================================ */ > > void initialize_metrics_common(void) > { > curl_global_init(CURL_GLOBAL_DEFAULT); > } > > /* ============================================================ > THREAD CURL INIT > ============================================================ */ > > static void initialize_thread_curl(void) > { > if (!curl_auth) > curl_auth = curl_easy_init(); > > if (!curl_metrics) > { > curl_metrics = curl_easy_init(); > > /* persistent HTTP connection */ > > curl_easy_setopt(curl_metrics, CURLOPT_HTTP_VERSION, > CURL_HTTP_VERSION_1_1); > > /* TCP keep alive */ > > curl_easy_setopt(curl_metrics, CURLOPT_TCP_KEEPALIVE, 1L); > curl_easy_setopt(curl_metrics, CURLOPT_TCP_KEEPIDLE, 30L); > curl_easy_setopt(curl_metrics, CURLOPT_TCP_KEEPINTVL, 15L); > } > > } > > /* ============================================================ > THREAD CURL CLEANUP > ============================================================ */ > > static void cleanup_thread_curl(void) > { > if (curl_auth) > { > curl_easy_cleanup(curl_auth); > curl_auth = NULL; > } > > if (curl_metrics) > { > curl_easy_cleanup(curl_metrics); > curl_metrics = NULL; > } > > if (headers_auth) > { > curl_slist_free_all(headers_auth); > headers_auth = NULL; > } > > if (headers_metrics) > { > curl_slist_free_all(headers_metrics); > headers_metrics = NULL; > } > > if (metrics_token) > { > free(metrics_token); > metrics_token = NULL; > } > > } > > // Function to cleanup CURL resources at the end of the process > void cleanup_curl_resources() { > > LOG_DEBUG("cleaned up curl resources using %s.. sleeping for 2 secs to > perform graceful cleanup", __func__); > > /** > if (curl_auth) { > curl_easy_cleanup(curl_auth); > curl_auth = NULL; > } > if (curl_metrics) { > curl_easy_cleanup(curl_metrics); > curl_metrics = NULL; > } > //Comment out below if block if needed to use curl_easy_perform() > if (multi_handle) { > curl_multi_cleanup(multi_handle); > multi_handle = NULL; > } > if (headers_auth) { > curl_slist_free_all(headers_auth); > headers_auth = NULL; > } > if (headers_metrics) { > curl_slist_free_all(headers_metrics); > headers_metrics = NULL; > } > > if (global_bearer_token != NULL) { > free(global_bearer_token); > global_bearer_token = NULL; > } > **/ > if (metrics_timer) > { > sr71_uv_timer_stop(metrics_timer); > metrics_timer = NULL; > } > > if (midnight_timer) > { > sr71_uv_timer_stop(midnight_timer); > midnight_timer = NULL; > } > > if (third_timer) > { > sr71_uv_timer_stop(third_timer); > third_timer = NULL; > } > > cleanup_thread_curl(); > //sleep(2); > curl_global_cleanup(); // Calling at the end of program > > } > /* ============================================================ > TOKEN EXPIRY CHECK > ============================================================ */ > > static int token_expired(void) > { > long now = time(NULL); > > if (!metrics_token) > return 1; > > if (now >= metrics_token_expiry) > return 1; > > return 0; > > } > > /* ============================================================ > AUTH RESPONSE CALLBACK > ============================================================ */ > > static size_t write_callback(void *ptr, size_t size, size_t nmemb, void > *userdata) > { > size_t total = size * nmemb; > > json_error_t error; > > json_t *json = json_loadb(ptr, total, 0, &error); > > if (!json) > { > LOG_ERROR("Failed to parse OAuth JSON response"); > return total; > } > > json_t *token = json_object_get(json, "access_token"); > json_t *expires = json_object_get(json, "expires_in"); > > if (json_is_string(token) && json_is_integer(expires)) > { > const char *value = json_string_value(token); > long expires_in = json_integer_value(expires); > > if (metrics_token) > free(metrics_token); > > metrics_token = strdup(value); > > /* refresh 60 seconds before expiry */ > > metrics_token_expiry = time(NULL) + expires_in - 60; > > LOG_INFO("OAuth token refreshed successfully. expires_in=%ld", > expires_in); > } > > json_decref(json); > > return total; > > } > > /* ============================================================ > FETCH AUTH TOKEN > ============================================================ */ > > static bool fetch_auth_token(void) > { > if (atomic_incr(&token_refresh_in_progress, 1) != 1) > { > atomic_incr(&token_refresh_in_progress, -1); > LOG_DEBUG("Token refresh already in progress"); > return true; > } > > const char *tenant = getenv("TENANT"); > const char *client = getenv("CLIENT_ID"); > const char *secret = getenv("CLIENT_SECRET"); > > if (!tenant || !client || !secret) > { > LOG_ERROR("OAuth environment variables missing"); > atomic_incr(&token_refresh_in_progress, -1); > return false; > } > > char auth_url[256]; > char auth_data[1024]; > > snprintf(auth_url, > sizeof(auth_url), > "https://login.microsoftonline.com/%s/oauth2/v2.0/token";, > tenant); > > snprintf(auth_data, > sizeof(auth_data), > > "grant_type=client_credentials&client_id=%s&client_secret=%s&scope=https://monitor.azure.com/.default";, > client, > secret); > > curl_easy_reset(curl_auth); > > headers_auth = curl_slist_append(NULL, > "Content-Type: application/x-www-form-urlencoded"); > > curl_easy_setopt(curl_auth, CURLOPT_URL, auth_url); > curl_easy_setopt(curl_auth, CURLOPT_POSTFIELDS, auth_data); > curl_easy_setopt(curl_auth, CURLOPT_HTTPHEADER, headers_auth); > > curl_easy_setopt(curl_auth, CURLOPT_WRITEFUNCTION, write_callback); > > curl_easy_setopt(curl_auth, CURLOPT_TIMEOUT_MS, 2000); > curl_easy_setopt(curl_auth, CURLOPT_CONNECTTIMEOUT_MS, 1500); > > CURLcode res = curl_easy_perform(curl_auth); > > long responseCode = 0; > curl_easy_getinfo(curl_auth, CURLINFO_RESPONSE_CODE, &responseCode); > > curl_slist_free_all(headers_auth); > headers_auth = NULL; > > atomic_incr(&token_refresh_in_progress, -1); > > if (res != CURLE_OK || responseCode != 200) > { > LOG_ERROR("OAuth request failed curl=%d http=%ld", res, responseCode); > return false; > } > > return true; > > } > > /* ============================================================ > POST METRICS > ============================================================ */ > > static bool post_metrics(char *json_str) > { > if (!metrics_token) > { > LOG_ERROR("Metrics token missing"); > return false; > } > > curl_easy_reset(curl_metrics); > > headers_metrics = NULL; > > headers_metrics = curl_slist_append(headers_metrics, > "Content-Type: application/json"); > > char auth_header[2048]; > > snprintf(auth_header, > sizeof(auth_header), > "Authorization: Bearer %s", > metrics_token); > > headers_metrics = curl_slist_append(headers_metrics, > auth_header); > > curl_easy_setopt(curl_metrics, CURLOPT_URL, opt_metrics_endp); > curl_easy_setopt(curl_metrics, CURLOPT_POSTFIELDS, json_str); > curl_easy_setopt(curl_metrics, CURLOPT_HTTPHEADER, headers_metrics); > > curl_easy_setopt(curl_metrics, CURLOPT_TIMEOUT_MS, 2000); > curl_easy_setopt(curl_metrics, CURLOPT_CONNECTTIMEOUT_MS, 1500); > > CURLcode res = curl_easy_perform(curl_metrics); > > long responseCode = 0; > > curl_easy_getinfo(curl_metrics, CURLINFO_RESPONSE_CODE, &responseCode); > > curl_slist_free_all(headers_metrics); > headers_metrics = NULL; > > if (res != CURLE_OK) > { > LOG_ERROR("Metrics POST failed: curl_error=%d (%s)", > res, > curl_easy_strerror(res)); > > return false; > } > > if (responseCode >= 200 && responseCode < 300) > { > LOG_DEBUG("Metrics POST successful. HTTP=%ld", responseCode); > return true; > } > > LOG_WARN("Metrics POST returned HTTP=%ld", responseCode); > > return false; > > } > > /* ============================================================ > WORKER THREAD > ============================================================ */ > > static void stats_worker_handler(uv_work_t *req) > { > if (!metrics_publish) > return; > > initialize_thread_curl(); > > prepare_json_callback callback = > (prepare_json_callback)req->data; > > if (!callback) > return; > > char *json_str = callback(); > > if (!json_str) > { > LOG_ERROR("Failed to generate metrics JSON"); > atomic_incr(&metrics_work_in_progress, -1); > return; > } > > /* proactive token refresh */ > > if (token_expired()) > { > LOG_DEBUG("OAuth token expired or near expiry"); > > if (!fetch_auth_token()) > { > LOG_ERROR("Token refresh failed"); > > free(json_str); > atomic_incr(&metrics_work_in_progress, -1); > return; > } > } > > if (!post_metrics(json_str)) > { > LOG_ERROR("Metrics publish failed"); > } > else > { > LOG_DEBUG("Metrics published successfully"); > } > > free(json_str); > > cleanup_thread_curl(); > atomic_incr(&metrics_work_in_progress, -1); > > } > > /* ============================================================ > TIMER CALLBACK > ============================================================ */ > > static void stats_timer_handler(void *cb_data) > { > if (!metrics_publish) > return; > > if (atomic_incr(&metrics_work_in_progress, 1) != 1) > { > atomic_incr(&metrics_work_in_progress, -1); > LOG_WARN("Skipping metrics run: previous run still active"); > return; > } > > uv_work_t req; > > req.data = cb_data; > > sr71_uv_queue_work( > &req, > sizeof(req), > (sr71_queue_handler *)stats_worker_handler > ); > > } > > static void midnight_reset_handler(void *arg) > { > LOG_DEBUG("Performing midnight reset of metrics (UTC)"); > > if (process_array_stats_enabled) > shares_process_stats_arr_reset(&process_stats_array); > else > shares_process_stats_reset(&process_stats); > > if (dbconn != NULL) > shares_process_stats_reset_db(); > else > LOG_ERROR("Metrics DB reset failed: dbconn NULL"); > > /* schedule next reset in 24 hours */ > > third_timer = sr71_uv_timer_start( > midnight_reset_handler, > 24 * 3600 * 1000, > 0, > NULL > ); > > } > > static int seconds_until_midnight_utc() > { > time_t now = time(NULL); > > struct tm utc; > gmtime_r(&now, &utc); > > int seconds_now = > utc.tm_hour * 3600 + > utc.tm_min * 60 + > utc.tm_sec; > > int seconds_midnight = 24 * 3600; > > int remaining = seconds_midnight - seconds_now; > > LOG_INFO( > "UTC time %02d:%02d:%02d | seconds_until_midnight=%d", > utc.tm_hour, > utc.tm_min, > utc.tm_sec, > remaining > ); > > return remaining; > > } > > static void schedule_midnight_reset(void) > { > int delay = seconds_until_midnight_utc(); > > LOG_DEBUG("Scheduling midnight reset in %d seconds", delay); > > midnight_timer = sr71_uv_timer_start( > midnight_reset_handler, > delay * 1000, > 24 * 3600 * 1000, > NULL > ); > > } > > /* ============================================================ > PUBLIC ENTRY > ============================================================ */ > > int open_metrics_enpoint(char *metrics_ep, > prepare_json_callback callback) > { > if (!metrics_ep || !callback) > { > LOG_ERROR("Invalid metrics endpoint or callback"); > return -1; > } > > snprintf(opt_metrics_endp, > sizeof(opt_metrics_endp), > "%s", > metrics_ep); > > opt_metrics_endp[sizeof(opt_metrics_endp) - 1] = '\0'; > > LOG_INFO("Metrics endpoint configured: %s", opt_metrics_endp); > > metrics_timer = sr71_uv_timer_start( > stats_timer_handler, > stats_interval, > stats_interval, > (void *)callback > ); > > return 0; > > } > Regards, > Sasmit Utkarsh > +91-7674022625 > -- > Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-library > Etiquette: https://curl.se/mail/etiquette.html >
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