[IPython-dev] ZMQ Segfault - IPython cluster
Dave Hirschfeld
dave.hirschfeld at gmail.com
Fri Aug 22 10:26:11 EDT 2014
MinRK <benjaminrk <at> gmail.com> writes:
>
>
> Yes, this is expected. The default for FD_SETSIZE is 1024 in libzmq (up
from the default of 64 on Windows), and can be increased at compile time. As
maintainer of pyzmq, I am reluctant for the defaults of pyzmq's bundled
libzmq to be different from the defaults for a traditionally built libzmq,
but zeromq-dev may be open to pushing up the default.
>
>
> -MinRK
>
>
> <pedant> a segfault is bad memory access; assert != segfault </pedant>
>
It was certainly unexpected for me! :P
There's also no mention of FD_SETSIZE on either the IPython or PyZMQ
websites AFAICS.
It was a fairly nasty bug to track down because the remote process failed
with no indication of why it did so. This is because Windows HPC 2008 only
caches the first 4000 characters of stdout/stderr so the error message never
got displayed (this has changed to a much more useful last 4k chars in
2012). To actually see the message I had to remote on the node and start the
ipcontroller process manually in a terminal.
After actually managing to get an error message I then had to search the
internet for what it meant and then recompile libzmq itself with VS2008
which isn't exactly a cakewalk for the uninitiated.
I agree it should be fixed in the upstream library so I've opened an issue
there - we can see what they say there...
https://github.com/zeromq/libzmq/issues/1165
Thanks,
Dave
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