lwt produces unhelpful backtraces

[nraynaud]

I get this backtrace from an error I'm hunting:

vhd-tool: internal error, uncaught exception:#012
          End_of_file#012
          Raised at file "src/core/lwt.ml", line 3008, characters 20-29#012
          Called from file "src/unix/lwt_main.ml", line 42, characters 8-18#012
          Called from file "src/impl.ml", line 994, characters 4-23#012
          Called from file "src/cmdliner_term.ml", line 27, characters 19-24#012
          Called from file "src/cmdliner.ml", line 27, characters 27-34#012
          Called from file "src/cmdliner.ml", line 106, characters 32-39

It leads here:

vhd-tool/src/impl.ml

Line 994 in 76a543f

Lwt_main.run thread;

which is not helpful.

Is there a way to get the backtraces in the LWT thread system?

At a deeper level, is lwt useful? vhd-tool seems to be called with the command line for every transaction in xen api, it is not a heavily loaded long-lived server with any meaningful concurrency. The only concurrency I see is read vs write and it's handled by sendfile(2).