At stop, when modules call remove_callback, they have to wait for the try_pop to timeout. stop is called serially (not in parallel) on modules, so this can make for long stop times. In particular, the readout app stop time in v3.0.0-rc5 can be several seconds, mostly due to this wait.
The event loop thread that's used for callbacks has a 500ms timeout on
try_pop(), here:https://github.com/DUNE-DAQ/iomanager/blob/df681a625b5fe1c679a2ec7eac29dca7a0147d5d/include/iomanager/Receiver.hpp#L157
At
stop, when modules callremove_callback, they have to wait for thetry_popto timeout.stopis called serially (not in parallel) on modules, so this can make for longstoptimes. In particular, the readout app stop time in v3.0.0-rc5 can be several seconds, mostly due to this wait.Fix is just to reduce the timeout. Say, 5ms?