After talking with Brian, we're pretty sure that this is only because
really, really old libevent didn't allow bitwise or-ing of the other
loop types, because what we really need is (EVLOOP_ONCE |
EVLOOP_NONBLOCK). And that's what EVLOOP_ONELOOP did (i.e., we
changed the logic of libevent's event.c to let ONELOOP do both ONCE
and NONBLOCK things).
In the new libevent version, we didn't implement EVLOOP_ONELOOP
properly. As a result, and we got hangs in the SM BTL add_procs
function. Note that the SM BTL wasn't to blame -- it was purely a
side-effect of bad ONELOOP integration (i.e., if you got past the SM
BTL add_procs, you may well have hung somewhere else).
This commit removes all ONELOOP customizations from event.c and
returns it to (almost) its original state from the libevent 2.0.7-rc
distribution. Everwhere in the code base where we used ONELOOP, we
now use (ONCE | NONBLOCK).
This commit was SVN r23957.
33c3b71317