Understand implications of multi-threading with openssl library #5
Labels
Comments
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
{{ message }}
As per libcurl threading guidelines, implement Exchange classes such that they can use multiple bets42::arthur::http_client's (i.e. multiple exchange sessions to allow requests in parallel) in light of known openssl multi-threading issues.
From http://curl.haxx.se/libcurl/c/libcurl-tutorial.html
Multi-threading Issues
The first basic rule is that you must never simultaneously share a libcurl handle (be it easy or multi or whatever) between multiple threads. Only use one handle in one thread at any time. You can pass the handles around among threads, but you must never use a single handle from more than one thread at any given time.
libcurl is completely thread safe, except for two issues: signals and SSL/TLS handlers. Signals are used for timing out name resolves (during DNS lookup) - when built without c-ares support and not on Windows.
If you are accessing HTTPS or FTPS URLs in a multi-threaded manner, you are then of course using the underlying SSL library multi-threaded and those libs might have their own requirements on this issue. Basically, you need to provide one or two functions to allow it to function properly. For all details, see this:
OpenSSL
http://www.openssl.org/docs/crypto/threads.html#DESCRIPTION
The text was updated successfully, but these errors were encountered: