eric-haibin-lin opened a new issue #17612: Gluon block thread safety bug URL: https://github.com/apache/incubator-mxnet/issues/17612 ``` import mxnet as mx import threading import queue import gluonnlp as nlp q = queue.Queue() count = 2 net = mx.gluon.nn.Dense((10)) net.initialize(mx.init.Uniform(), ctx=[mx.gpu(0), mx.gpu(1)]) mx.nd.waitall() def fn(net, ctx): with mx.autograd.record(): x = mx.nd.random.uniform(low=0, high=1000, shape=(10, 128), ctx=ctx) q.put(net(x)) mx.nd.waitall() return threads = [] for i in range(count): t = threading.Thread(target=fn, args=(net, mx.gpu())) threads.append(t) for i in range(count): threads[i].start() for i in range(count): threads[i].join() ys = [] for i in range(count): ys.append(q.get()) print(ys) ``` Error: ``` Exception in thread Thread-2: Traceback (most recent call last): File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 1154, in forward params = {k: v.data(ctx) for k, v in self._reg_params.items()} File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 1154, in <dictcomp> params = {k: v.data(ctx) for k, v in self._reg_params.items()} File "/home/ubuntu/src/mxnet/python/mxnet/gluon/parameter.py", line 565, in data return self._check_and_get(self._data, ctx) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/parameter.py", line 236, in _check_and_get "num_features, etc., for network layers."%(self.name)) mxnet.gluon.parameter.DeferredInitializationError: Parameter 'dense0_weight' has not been initialized yet because initialization was deferred. Actual initialization happens during the first forward pass. Please pass one batch of data through the network before accessing Parameters. You can also avoid deferred initialization by specifying in_units, num_features, etc., for network layers. During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 976, in _deferred_infer_shape self.infer_shape(*args) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 1074, in infer_shape self._infer_attrs('infer_shape', 'shape', *args) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 1058, in _infer_attrs inputs, out = self._get_graph(*args) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 928, in _get_graph out = self.hybrid_forward(symbol, *grouped_inputs, **params) # pylint: disable=no-value-for-parameter File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 94, in __exit__ self._name_scope.__exit__(ptype, value, trace) AttributeError: 'NoneType' object has no attribute '__exit__' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/usr/lib/python3.5/threading.py", line 914, in _bootstrap_inner self.run() File "/usr/lib/python3.5/threading.py", line 862, in run self._target(*self._args, **self._kwargs) File "test.py", line 29, in fn q.put(net(x)) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 696, in __call__ out = self.forward(*args) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 1156, in forward self._deferred_infer_shape(x, *args) File "/home/ubuntu/src/mxnet/python/mxnet/gluon/block.py", line 980, in _deferred_infer_shape raise ValueError(error_msg) ValueError: Deferred initialization failed because shape cannot be inferred. 'NoneType' object has no attribute '__exit__' ```
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