Trainer runs indefinitely if `fast_dev_run=True` when iterating over `self.logger`

[ritsuki1227]

🐛 Bug

If you specify fast_dev_run=True and multiple loggers, and include a loop implementation over the LoggerCollection object for training, then the loop in the training runs indefinitely. If fast_dev_run=False, it runs correctly.

To Reproduce

A slightly modified version of the BoringModel script:

import os

import torch
from torch.utils.data import DataLoader, Dataset

from pytorch_lightning import LightningModule, Trainer
from pytorch_lightning.loggers import MLFlowLogger, TensorBoardLogger


class RandomDataset(Dataset):
    def __init__(self, size, length):
        self.len = length
        self.data = torch.randn(length, size)

    def __getitem__(self, index):
        return self.data[index]

    def __len__(self):
        return self.len


class BoringModel(LightningModule):
    def __init__(self):
        super().__init__()
        self.layer = torch.nn.Linear(32, 2)

    def forward(self, x):
        return self.layer(x)

    def training_step(self, batch, batch_idx):
        loss = self(batch).sum()
        self.log("train_loss", loss)
        return {"loss": loss}
    
    def on_train_end(self):
        # added
        print('foo')
        for logger in self.logger:
            print('bar')

    def validation_step(self, batch, batch_idx):
        loss = self(batch).sum()
        self.log("valid_loss", loss)

    def test_step(self, batch, batch_idx):
        loss = self(batch).sum()
        self.log("test_loss", loss)

    def configure_optimizers(self):
        return torch.optim.SGD(self.layer.parameters(), lr=0.1)


def run():
    train_data = DataLoader(RandomDataset(32, 64), batch_size=2)
    val_data = DataLoader(RandomDataset(32, 64), batch_size=2)
    test_data = DataLoader(RandomDataset(32, 64), batch_size=2)
    
    tb_logger = TensorBoardLogger(save_dir='foo') # added
    mlf_logger = MLFlowLogger() # added

    model = BoringModel()
    trainer = Trainer(
        default_root_dir=os.getcwd(),
        limit_train_batches=1,
        limit_val_batches=1,
        num_sanity_val_steps=0,
        max_epochs=1,
        # enable_model_summary=False,
        fast_dev_run=True, # added
        logger=[tb_logger, mlf_logger] # added
    )
    trainer.fit(model, train_dataloaders=train_data, val_dataloaders=val_data)
    trainer.test(model, dataloaders=test_data)


if __name__ == "__main__":
    run()

Expected behavior

The training finishes when fast_dev_run=True.

Environment

• PyTorch Lightning Version (e.g., 1.3.0): 1.4.9
• PyTorch Version (e.g., 1.8): 1.9.0+cu111
• Python version: 3.9.6
• OS (e.g., Linux): Ubuntu 18.04
• CUDA/cuDNN version: CUDA: 11.1.1, cuDNN: 8.0.5
• GPU models and configuration: NVIDIA Tesla T4
• How you installed PyTorch (conda, pip, source): source
• If compiling from source, the output of torch.__config__.show():

'PyTorch built with:\n  - GCC 7.3\n  - C++ Version: 201402\n  - Intel(R) Math Kernel Library Version 2020.0.0 Product Build 20191122 for Intel(R) 64 architecture applications\n  - Intel(R) MKL-DNN v2.1.2 (Git Hash 98be7e8afa711dc9b66c8ff3504129cb82013cdb)\n  - OpenMP 201511 (a.k.a. OpenMP 4.5)\n  - NNPACK is enabled\n  - CPU capability usage: AVX2\n  - CUDA Runtime 11.1\n  - NVCC architecture flags: -gencode;arch=compute_37,code=sm_37;-gencode;arch=compute_50,code=sm_50;-gencode;arch=compute_60,code=sm_60;-gencode;arch=compute_70,code=sm_70;-gencode;arch=compute_75,code=sm_75;-gencode;arch=compute_80,code=sm_80;-gencode;arch=compute_86,code=sm_86\n  - CuDNN 8.0.5\n  - Magma 2.5.2\n  - Build settings: BLAS_INFO=mkl, BUILD_TYPE=Release, CUDA_VERSION=11.1, CUDNN_VERSION=8.0.5, CXX_COMPILER=/opt/rh/devtoolset-7/root/usr/bin/c++, CXX_FLAGS= -Wno-deprecated -fvisibility-inlines-hidden -DUSE_PTHREADPOOL -fopenmp -DNDEBUG -DUSE_KINETO -DUSE_FBGEMM -DUSE_QNNPACK -DUSE_PYTORCH_QNNPACK -DUSE_XNNPACK -DSYMBOLICATE_MOBILE_DEBUG_HANDLE -O2 -fPIC -Wno-narrowing -Wall -Wextra -Werror=return-type -Wno-missing-field-initializers -Wno-type-limits -Wno-array-bounds -Wno-unknown-pragmas -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable -Wno-unused-function -Wno-unused-result -Wno-unused-local-typedefs -Wno-strict-overflow -Wno-strict-aliasing -Wno-error=deprecated-declarations -Wno-stringop-overflow -Wno-psabi -Wno-error=pedantic -Wno-error=redundant-decls -Wno-error=old-style-cast -fdiagnostics-color=always -faligned-new -Wno-unused-but-set-variable -Wno-maybe-uninitialized -fno-math-errno -fno-trapping-math -Werror=format -Wno-stringop-overflow, LAPACK_INFO=mkl, PERF_WITH_AVX=1, PERF_WITH_AVX2=1, PERF_WITH_AVX512=1, TORCH_VERSION=1.9.0, USE_CUDA=ON, USE_CUDNN=ON, USE_EXCEPTION_PTR=1, USE_GFLAGS=OFF, USE_GLOG=OFF, USE_MKL=ON, USE_MKLDNN=ON, USE_MPI=OFF, USE_NCCL=ON, USE_NNPACK=ON, USE_OPENMP=ON, \n'

• Any other relevant information:

Additional context

[Programmer-RD-AI]

hi,

Can you check

https://discuss.pytorch.org/t/rtx-3070-amp-doesnt-seem-to-be-working/118835

and

https://stackoverflow.com/questions/66315250/enable-multi-threading-on-caffe2

[ritsuki1227]

@Programmer-RD-AI
Thank you for sharing.
FYI, it can also be reproduced on my macOS environment without CUDA and GPUs.
I believe the problem is related to DummyLogger class of pytorch lightning rather than naive pytorch.

[Programmer-RD-AI]

Hi,

OK I will try to find a solution

[awaelchli]

@ritsuki1227 thanks for reporting this and the repro script (extremely valuable)! It is a fast_dev_run bug and you are right with your suspicion about dummy logger. We need to add something like

    def __iter__(self):
        yield from ()

to the DummyLogger