Created
October 13, 2016 23:20
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Better initialize_all_variables which respects variable dependencies and doesn't rerun initializers
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# testing variable order init | |
import tensorflow as tf | |
def initialize_all_variables(sess=None): | |
"""Initializes all uninitialized variables in correct order. Initializers | |
are only run for uninitialized variables, so it's safe to run this multiple | |
times. | |
Args: | |
sess: session to use. Use default session if None. | |
""" | |
from tensorflow.contrib import graph_editor as ge | |
def make_initializer(var): | |
def f(): | |
return tf.assign(var, var.initial_value).op | |
return f | |
def make_noop(): return tf.no_op() | |
def make_safe_initializer(var): | |
"""Returns initializer op that only runs for uninitialized ops.""" | |
return tf.cond(tf.is_variable_initialized(var), make_noop, | |
make_initializer(var), name="safe_init_"+var.op.name).op | |
if not sess: | |
sess = tf.get_default_session() | |
g = tf.get_default_graph() | |
safe_initializers = {} | |
for v in tf.all_variables(): | |
safe_initializers[v.op.name] = make_safe_initializer(v) | |
# initializers access variable vaue through read-only value cached in | |
# <varname>/read, so add control dependency to trigger safe_initializer | |
# on read access | |
for v in tf.all_variables(): | |
var_name = v.op.name | |
var_cache = g.get_operation_by_name(var_name+"/read") | |
ge.reroute.add_control_inputs(var_cache, [safe_initializers[var_name]]) | |
sess.run(tf.group(*safe_initializers.values())) | |
# remove initializer dependencies to avoid slowing down future variable reads | |
for v in tf.all_variables(): | |
var_name = v.op.name | |
var_cache = g.get_operation_by_name(var_name+"/read") | |
ge.reroute.remove_control_inputs(var_cache, [safe_initializers[var_name]]) | |
################################################################################ | |
# Tests | |
################################################################################ | |
def simple_test(): | |
tf.reset_default_graph() | |
a = tf.Variable(1) | |
b = tf.Variable(a*2) | |
sess = tf.InteractiveSession() | |
initialize_all_variables() | |
assert sess.run(tf.size(tf.report_uninitialized_variables()))==0 | |
def random_test(): | |
"""Make sure variables don't get reinitialized.""" | |
tf.reset_default_graph() | |
a = tf.get_variable("A", shape=()) | |
b = tf.Variable(a, name="B") | |
sess = tf.InteractiveSession() | |
initialize_all_variables() | |
c = tf.Variable(a, name="C") | |
initialize_all_variables() | |
assert sess.run(tf.equal(a, b)) | |
assert sess.run(tf.equal(a, c)) | |
assert sess.run(tf.equal(b, c)) | |
def complex_test(): | |
tf.reset_default_graph() | |
e = tf.Variable(1., name="e") | |
f = tf.Variable(e, name="f") | |
d = tf.Variable(f, name="d") | |
b = tf.Variable(f, name="b") | |
c = tf.Variable(d+e, name="c") | |
a = tf.Variable(b+c, name="a") | |
sess = tf.InteractiveSession() | |
initialize_all_variables(sess) | |
assert sess.run(a) == 3. | |
if __name__=='__main__': | |
simple_test() | |
random_test() | |
complex_test() | |
print("Tests passed") |
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very useful! thanks