curl_global_cleanup() needed before exiting binary (exe)?

[user706]

Hi,

is curl_global_cleanup() needed if I'm exiting the binary (executable)?

In other words:
What happens if I repeatedly do the following sequentially (say thousands of times per minute):

• start an executable that runs curl_global_init(CURL_GLOBAL_ALL);
  and then immediately exits without (!) calling curl_global_cleanup().

??

Will I somehow have less and less memory? Or any other problem?
Or will everything be clean, as if curl_global_cleanup() would have been called before exiting?

Background: If it is really needed, then I have to write signal handlers, such that I ensure that curl_global_cleanup() is still called when terminating an application/service via systemctl stop myapplication. Is that really needed? Any pointers? Thanks.

Thanks.

PS: Will things be somehow different, if I start such an application thousands of times per minute.... concurrently, instead of sequentially?

[dfandrich]

On Thu, May 16, 2024 at 05:24:49AM -0700, user706 wrote: What happens if I repeatedly do the following sequentially (say thousands of times per minute): • start an executable that runs curl_global_init(CURL_GLOBAL_ALL); and then immediately exits without (!) calling curl_global_cleanup(). ?? Will I somehow have less and less memory? Or any other problem? Or will everything be clean, as if curl_global_cleanup() would have been called before exiting?

Once a process exits, your operating system will free up all the nonpersistent resources used by that process, so there won't be anything left once it's done. Theoretically, some libcurl dependency could leave things like lock files lying around that wouldn't be cleaned up, but I'm not aware of anything like that currently being an issue. Also, leak checking systems like valgrind or LeakSanitizer will raise warnings on exit, but you probably aren't planning on using those.

[user706]

I know all this.

But the curl documentation is really quite weird in that respect, as it seems to suggest that I really must call curl_global_cleanup() before exiting the program. Just check the example, where it's called before main() exits: https://curl.se/libcurl/c/curl_global_cleanup.html

So I'm wondering... maybe it allocates resources in some other service (and different unrelated process)... maybe openssl or TLS or whatever??

[dfandrich]

If you're concerned about cleaning up everything properly in all cases, follow the documentation and call curl_global_cleanup() before exit. But if your testing reveals that the OS is doing a fine job of cleaning up on its own, you always have the freedom to ignore the documentation.