StopIteration Error while running inference on the frames

[mohsin-ashraf]

Hi, team Pixeltable. I am working with the Pixeltable frame views. While the view gets created successfully when I try to access it I get to access the frames of the view I get the following error.

---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/row_builder.py:306, in RowBuilder.eval(self, data_row, ctx, profile, ignore_errors)
    305 start_time = time.perf_counter()
--> 306 expr.eval(data_row, self)
    307 if profile is not None:

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/column_ref.py:90, in ColumnRef.eval(self, data_row, row_builder)
     89 self.iterator.set_pos(data_row.pk[self.pos_idx])
---> 90 res = next(self.iterator)
     91 data_row[self.slot_idx] = res[self.col.name]

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/iterators/video.py:64, in FrameIterator.__next__(self)
     63     self.video_reader = None
---> 64     raise StopIteration
     65 if pos_frame % self.frame_freq == 0:

StopIteration: 

During handling of the above exception, another exception occurred:

ExprEvalError                             Traceback (most recent call last)
File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py:327, in DataFrame.collect(self)
    326 result_rows = []
--> 327 for data_row in self._exec():
    328     result_row = [data_row[e.slot_idx] for e in self._select_list_exprs]

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py:291, in DataFrame._exec(self)
    290 try:
--> 291     for row_batch in plan:
    292         for data_row in row_batch:

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exec/expr_eval_node.py:45, in ExprEvalNode.__next__(self)
     44 for cohort in self.cohorts:
---> 45     self._exec_cohort(cohort, input_batch)
     46 _logger.debug(f'ExprEvalNode: returning {len(input_batch)} rows')

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exec/expr_eval_node.py:144, in ExprEvalNode._exec_cohort(self, cohort, rows)
    143     for row_idx in range(batch_start_idx, batch_start_idx + num_batch_rows):
--> 144         self.row_builder.eval(
    145             rows[row_idx], segment_ctx, self.ctx.profile, ignore_errors=self.ctx.ignore_errors)
    146 else:

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/row_builder.py:315, in RowBuilder.eval(self, data_row, ctx, profile, ignore_errors)
    314 input_vals = [data_row[d.slot_idx] for d in expr.dependencies()]
--> 315 raise excs.ExprEvalError(
    316     expr, f'expression {expr}', data_row.get_exc(expr.slot_idx), exc_tb, input_vals, 0)

ExprEvalError: (<pixeltable.exprs.column_ref.ColumnRef object at 0x28c4a0d90>, 'expression frame', StopIteration(), <traceback object at 0x28c36af40>, [], 0)

During handling of the above exception, another exception occurred:

Error                                     Traceback (most recent call last)
Cell In[22], line 1
----> 1 view.select(view.frame).show(5)

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py:300, in DataFrame.show(self, n)
    298 def show(self, n: int = 20) -> DataFrameResultSet:
    299     assert n is not None
--> 300     return self.limit(n).collect()

File /opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py:347, in DataFrame.collect(self)
    345         # [-1:0:-1]: leave out entry 0 and reverse order, so that the most recent frame is at the top
    346         msg += f'\nStack:\n{nl.join(stack_trace[-1:1:-1])}'
--> 347     raise exc.Error(msg)
    348 except sql.exc.DBAPIError as e:
    349     raise exc.Error(f'Error during SQL execution:\n{e}')

Error: In row 0 the expression frame encountered exception StopIteration:

Stack:
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/iterators/video.py", line 64, in __next__
    raise StopIteration```


Accessing other columns works fine. Also this error is not occurring for all the views but for some. Basically I am working with 3 views, and out of these views I get this error for sometime all views, one of the view, this error is very random.

[mohsin-ashraf]

For some views which gets generated properly, when I try to inference on them to get the bounding boxes I get the same error

python inference/pre_annotate_view.py -v deployment_33_fps_0_5_tp 
2024-01-30 18:35:03,397 INFO pixeltable env.py:188: found database postgresql://postgres:@/pixeltable?host=/Users/mohsinashraf/.pixeltable/pgdata
Computing cells: 362cells [02:58,  2.02cells/s]                                                                                                                                                                                                      
added 273 column values with 0 errors
Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/row_builder.py", line 306, in eval
    expr.eval(data_row, self)
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/column_ref.py", line 90, in eval
    res = next(self.iterator)
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/iterators/video.py", line 64, in __next__
    raise StopIteration
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py", line 327, in collect
    for data_row in self._exec():
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py", line 291, in _exec
    for row_batch in plan:
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exec/expr_eval_node.py", line 45, in __next__
    self._exec_cohort(cohort, input_batch)
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exec/expr_eval_node.py", line 144, in _exec_cohort
    self.row_builder.eval(
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/exprs/row_builder.py", line 315, in eval
    raise excs.ExprEvalError(
pixeltable.exceptions.ExprEvalError: (<pixeltable.exprs.column_ref.ColumnRef object at 0x16e042980>, 'expression frame', StopIteration(), <traceback object at 0x16e17f680>, [], 0)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/mohsinashraf/obvio/ObvioEngine/vision/infra/pixeltable/inference/pre_annotate_view.py", line 36, in <module>
    df = view.select(*eval(columns)).collect().to_pandas()
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/dataframe.py", line 347, in collect
    raise exc.Error(msg)
pixeltable.exceptions.Error: In row 0 the expression frame encountered exception StopIteration:

Stack:
  File "/opt/homebrew/Caskroom/miniconda/base/envs/pixeltable/lib/python3.10/site-packages/pixeltable/iterators/video.py", line 64, in __next__
    raise StopIteration

Code for inference is given below.

@pxt.udf(return_type=pxt.JsonType(), param_types=[pxt.ImageType()])
def detection_in_coco(img):
    img = np.array(img)
    img = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
    detections = detector.detect(img)
    pre_annotations = []
    if detections:
        for detection in detections:
            bbox = detection[:4]
            conf, label = detection[4:]
            if int(label) not in (0,2,6,8): continue
            bbox = list(map(int, bbox))
            x,y,w,h = bbox
            pre_annotations.append({
                'bbox': [x,y,w,h],
                'category': CATEGORY_MAP[int(label)],
            })
    return pre_annotations

[mkornacker]

Could you please also include the table and view definitions and the queries you're running?

[orm011]

We are looking into this issue, we think we have found the problem. We'll let you know