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Re: Endless loop on curl_multi_cleanup

From: Ray Satiro via curl-library <>
Date: Sun, 2 Oct 2016 16:41:32 -0400

On 10/2/2016 4:06 PM, Dan Fandrich wrote:
> I've discovered a case where curl_multi_cleanup() can end up in an endless
> loop when it's called with a transfer ongoing. In such a case,
> close_all_connections() loops around all the connections in the connection
> cache calling Curl_disconnect() on each and not exiting until all connections
> in the cache are closed. However, if the connection is still in use,
> Curl_disconnect() does NOT remove the connection from the cache (the
> Curl_disconnect, usecounter: code path) and the loop around the connection
> cache continues, ad infinitum.
> I'm not sure the right way to solve this. Should the forced-close bit be set on
> all connections first to make sure they're closed? Or does whole situation
> simply invalid because there aren't supposed to be any easy handles attached to
> the multi handle as curl_multi_cleanup() is called? The man page doesn't
> actually come right out and say that this isn't allowed, but does imply it.
> This situation can occur in test 1500 when the TEST_ERR_MAJOR_BAD code path is
> taken (such as during the memory torture test). That test doesn't actually
> ever call curl_multi_remove_handle() as the man page recommends, and calls the
> multi and easy cleanup functions in the opposite order to the recommendation,
> which makes me think that other code out there doing the same and
> curl_multi_cleanup() should handle the situation without hanging.

Is there really something to solve here, the doc says
"curl_multi_cleanup should be called when all easy handles are removed" [1].


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Received on 2016-10-02