qFunction issue

[drougui]

Hi,
I got an issue by simply running the example script cartpole-td.sh:

Error: Experiment was not successfully run.
...rch/install/share/lua/5.1/twrl/agent/model/qFunction.lua:22: attempt to index local 'state' (a nil value)
stack traceback:
...drougard/torch/install/share/lua/5.1/twrl/experiment.lua:62: in function '__index'
...rch/install/share/lua/5.1/twrl/agent/model/qFunction.lua:22: in function 'getFeatures'
...rch/install/share/lua/5.1/twrl/agent/model/qFunction.lua:43: in function 'estimateQ'
...rch/install/share/lua/5.1/twrl/agent/model/qFunction.lua:56: in function 'estimateAllQ'
...orch/install/share/lua/5.1/twrl/agent/policy/egreedy.lua:20: in function 'selectAction'
...drougard/torch/install/share/lua/5.1/twrl/experiment.lua:37: in function <...drougard/torch/install/share/lua/5.1/twrl/experiment.lua:15>
[C]: in function 'xpcall'
...drougard/torch/install/share/lua/5.1/twrl/experiment.lua:66: in function <...drougard/torch/install/share/lua/5.1/twrl/experiment.lua:1>
run.lua:69: in main chunk
[C]: in function 'dofile'
...TWRL/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:150: in main chunk
[C]: at 0x00406670

Strangely this error disappears when asking for more videos, e.g. -video 5.
It disappears also when adding enough prints in qFunction.lua (in order to track the error's origin).
Hence it seems to be related to a process (server?) unable to provide the state at the proper time (it becomes able to do it when slowing down all processes, e.g. by adding video or printing enough data).

The issue has been observed on two PCs using Ubuntu 14.04.