Maybe the resident expert Salva would explain exactly what blocking() does, so we can sort this out once and for all.
blocking is just a wrapper for the libssh2 method libssh2_session_set_blocking.

When blocking is active (the default), any method called will wait for the requested action to be completed before returning control to the caller.

When it is deactivated, method calls that can not be fulfilled immediately return the libssh2 equivalent of an EAGAIN error, LIBSSH2_ERROR_EAGAIN.

Unfortunately, the internal design of libssh2 for non-blocking mode is not very good and it imposes several limitations on how it can be used (for instance, once you get a LIBSSH2_ERROR_EAGAIN error, you are only allowed to retry just the failed method call with exactly the same arguments -at the C level- until it returns success). It is also quite buggy, so things that should work doesn't, not all the methods in the library are supported, and some even may corrupt the session.

My experience when using it for more than trivial things, is that you often need to look into the C library and the XS code in order to see what is going on, and to work around all its quirks.

In reply to Re^2: using SSH2 backend by salva
in thread using SSH2 backend by Aldebaran

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