[Caml-list] Unix.Unix_error(31, "write", "") raised from format.ml!? This is not right.

[Arlen Cuss <celtic@sairyx.org>]

Hi all,

I'm getting bizarre errors in a program which multiplexes on 50-100
sockets (some Unix domain, some TCP), where an error will apparently
occur in "write", but the entire backtrace is limited to 'format.ml':

backtrace: Raised at file "format.ml", line 194, characters 15-26
Called from file "format.ml", line 420, characters 8-33
Called from file "format.ml", line 435, characters 6-24

The backtrace does describe a correct path through format.ml:

194    | _ -> raise Empty_queue

420   match peek_queue state.pp_queue with

435   try advance_loop state with

It's hard to determine what's going on, because for some reason the
backtrace is limited to this file, and none of my own code. I'm a bit
lost as to how these errors are being raised:

Exception Unix.Unix_error(31, "write", "") occurred
Exception Unix.Unix_error(56, "write", "") occurred

Both are occurring with the same reported backtrace; the former is Unix
error EMLINK (too many links), the latter EISCONN (socket is connected);
the strange thing is that *neither* of these errors should be throwable
on a write() call!

I've ensured I'm correctly compiling with debug info, so I'm a bit lost.
I can only assume a sprintf or similar call somewhere is going haywire.

Anyone seen anything like this before?

Best,
Arlen