I am trying to save variables through checkpoints to introduce fault tolerance to my program. I am trying to achieve this by using the MonitoredTrainingSession function. The following is my configuration:-
import tensorflow as tf
global_step = tf.Variable(10, trainable=False, name='global_step')
x = tf.constant(2)
with tf.device("/job:local/task:0"):
y1 = tf.Variable(x + 300)
with tf.device("/job:local/task:1"):
y2 = tf.Variable(x**2)
with tf.device("/job:local/task:2"):
y3 = tf.Variable(5*x)
with tf.device("/job:local/task:3"):
y0 = tf.Variable(x - 66)
y = y0 + y1 + y2 + y3
model = tf.global_variables_initializer()
saver = tf.train.Saver(sharded=True)
chief = tf.train.ChiefSessionCreator(scaffold=None, master='grpc://localhost:2222', config=None, checkpoint_dir='/home/tensorflow/codes/checkpoints')
summary_hook = tf.train.SummarySaverHook(save_steps=None, save_secs=10, output_dir='/home/tensorflow/codes/savepoints', summary_writer=None, scaffold=None, summary_op=tf.summary.tensor_summary(name="y", tensor=y))
saver_hook = tf.train.CheckpointSaverHook(checkpoint_dir='/home/tensorflow/codes/checkpoints', save_secs=None, save_steps=True, saver=saver, checkpoint_basename='model.ckpt', scaffold=None)
# with tf.train.MonitoredSession(session_creator=ChiefSessionCreator,hooks=[saver_hook, summary_hook]) as sess:
with tf.train.MonitoredTrainingSession(master='grpc://localhost:2222', is_chief=True, checkpoint_dir='/home/tensorflow/codes/checkpoints',
scaffold=None, hooks=[saver_hook,summary_hook], chief_only_hooks=None, save_checkpoint_secs=None, save_summaries_steps=True, config=None) as sess:
while not sess.should_stop():
sess.run(tf.global_variables_initializer())
while not sess.should_stop():
result = sess.run(y)
print(result)
I get the following RuntimeError which I am unable to resolve:-
Traceback (most recent call last):
File "add_1.py", line 39, in <module>
sess.run(tf.global_variables_initializer())
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/variables.py", line 1187, in global_variables_initializer
return variables_initializer(global_variables())
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/variables.py", line 1169, in variables_initializer
return control_flow_ops.group(*[v.initializer for v in var_list], name=name)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/control_flow_ops.py", line 2773, in group
deps.append(_GroupControlDeps(dev, ops_on_device[dev]))
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/control_flow_ops.py", line 2721, in _GroupControlDeps
return no_op(name=name)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/gen_control_flow_ops.py", line 186, in no_op
result = _op_def_lib.apply_op("NoOp", name=name)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/framework/op_def_library.py", line 759, in apply_op
op_def=op_def)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/framework/ops.py", line 2199, in create_op
self._check_not_finalized()
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/framework/ops.py", line 1925, in _check_not_finalized
raise RuntimeError("Graph is finalized and cannot be modified.")
RuntimeError: Graph is finalized and cannot be modified.
The root cause for your error seems to be that MonitoredTrainingSession has finalized (frozen) the graph and your tf.global_variable_initializer()
is no longer able to modify it.
Having said that, there are multiple things that require attention:
1) Why do you try to repeatedly initialize all variables here?
while not sess.should_stop():
sess.run(tf.global_variables_initializer())
2) It seems some of your code is already included in MonitoredTrainingSession
, e.g. ChiefSessionCreator
. Can you please take another look at the code (https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/training/monitored_session.py#L243) or search for its sample usage and see how MonitoredTrainingSession
is supposed to be used?
This may not be recommended for your use case, but it is possible to unfinalize a Graph:
sess.graph._unsafe_unfinalize()
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