Repository: stepjam/RLBench
Issue: KnifeinBlock - Please Raise an Issue
Root cause: Algorithmic Error

Hi! Amazing framework - I was playing around with it and an issue occured that requested I raise it here - 

```
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Warning: SBL: Skipping invalid start state (invalid state)
         at line 248 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/base/src/Planner.cpp
Error:   SBL: Motion planning start tree could not be initialized!
         at line 101 in /home/marc/Documents/ompl-1.4.2-Source/src/ompl/geometric/planners/sbl/src/SBL.cpp
Traceback (most recent call last):
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/task_environment.py", line 70, in reset
    randomly_place=not self._static_positions)
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/backend/scene.py", line 93, in init_episode
    descriptions = self._active_task.init_episode(index)
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/tasks/put_knife_in_knife_block.py", line 31, in init_episode
    self.boundary.sample(self.chopping_board)
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/backend/spawn_boundary.py", line 176, in sample
    'Could not place the object within the boundary due to '
rlbench.backend.exceptions.BoundaryError: Could not place the object within the boundary due to collision with other objects in the boundary.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "single_task_rl_with_demos.py", line 35, in <module>
    demos = task.get_demos(20, live_demos=live_demos)
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/task_environment.py", line 238, in get_demos
    demos = self._get_live_demos(amount)
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/task_environment.py", line 248, in _get_live_demos
    self.reset()
  File "/home/sholto/.local/lib/python3.7/site-packages/rlbench/task_environment.py", line 75, in reset
    % self._task.get_name()) from e
rlbench.task_environment.TaskEnvironmentError: Could not place the task put_knife_in_knife_block in the scene. This should not happen, please raise an issues on this task.
QObject::~QObject: Timers cannot be stopped from another thread
QMutex: destroying locked mutex
```


Hi,
Thanks for raising. The tasks are randomly placed in the scene, if they cannot be placed after a certain number of tries then this error is raises. I will look in to why it is taking so many tries to place this task. 
Best,
Stephen