Question about MultiDatasetsEvaluator

[jigongbao]

When using MultiDatasetsEvaluator, I find that it will show that the evaluator shows no cumulative_sizes making it impossible to proceed, but my val_dataloader uses concatdatasets.
Here is my config:
val_evaluator = dict(
type='MultiDatasetsEvaluator',
metrics=metrics,
dataset_prefixes=dataset_prefixes
)
val_dataloader = dict(
batch_size=val_batch_size_per_gpu,
num_workers=val_num_workers,
persistent_workers=persistent_workers,
pin_memory=True,
drop_last=False,
sampler=dict(type='DefaultSampler', shuffle=False),
dataset=dict(
type='ConcatDataset',
datasets=[
A3_roi1_dataset_val,
A3_roi2_dataset_val,
A3_roi3_dataset_val,
A3_roi4_dataset_val,
A3_roi5_dataset_val
]
)
)

[MiXaiLL76]

I recently developed a project where I used MultiDatasetsEvaluator

val_dataloader = dict(
    batch_size=BATCH//2,
    num_workers=BATCH//2,
    drop_last=False,
    persistent_workers=True,
    sampler=dict(type="DefaultSampler", shuffle=False),
    dataset=dict(
        type="ConcatDataset",
        datasets=[val_real_dataset, val_synth_dataset],
    ),
)

and

if use_segm:
    metrics.append("segm")

val_evaluator = dict(
    type='MultiDatasetsEvaluator',
    metrics=[
        dict(type=metric_type, metric=metrics, classwise=True),
        dict(type=metric_type, metric=metrics, classwise=True),
    ],
    dataset_prefixes=["real", "synth"]
)

Everything worked great