I have lots of code using inproc. always works fine for me.
On Jun 1, 2015, at 2:24 PM, Garrett D'Amore <garrett@xxxxxxxxxx> wrote:
Just so everyone knows it: the inproc transport in libnanomsg is pretty
clearly fraught with problems. At the most basic level, it suffers from a
lack of synchronization control (locks) protecting some of the state shared
between the two endpoints of a connection (in particular the state machine
content is not carefully protected, although both ends participate in
informing each other of new content.)
Since the only conceivably useful case for inproc I can think of involves
different threads on the two different ends of a connection, this makes it
effectively useless until those bugs are fixed.
At least one person has volunteered to work on this part of the code. I’ve
tried to fix a few of the issues, but the heart of the issue is going to
require some careful design work with the locking to ensure it works, and
does not create new deadlock scenarios. As I don’t use inproc myself, I
can’t really say that this has any sense of priority on my part — I’d like to
fix it, but my own itches tend to get scratched first, and I’ve plenty enough
of those.
In the meantime, I’d appreciate it if folks can try to avoid using inproc
where possible, and in particular try to refrain from filing new bugs against
inproc. With the lack of thread-safety in it, I suspect *many* of the
strange behaviors folks have reported will go away when inproc is properly
fixed.
Note that none of this applies to mangos. The inproc code in mangos, as well
as the rest of mangos, has been carefully designed to be completely thread
safe, and should not have any issues there. (I can’t imagine what you’d use
inproc for in a Go program… but its there. Inproc in mangos is not
compatible with libnanomsg inproc, in the sense that you can’t pass messages
between them.)
(One idea I’ve been toying with is to have inproc convert to using a pipe()
based pair of file descriptors. This would let us use the kernel and avoid
the synchronization problems altogether, although it would make inproc
noticeably slower.)
- Garrett
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