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Represents a (possibly partial) specification for a TensorFlow device.
Inherits From: DeviceSpec
tf.compat.v1.DeviceSpec(
job=None, replica=None, task=None, device_type=None, device_index=None
)
DeviceSpecs are used throughout TensorFlow to describe where state is stored
and computations occur. Using DeviceSpec allows you to parse device spec
strings to verify their validity, merge them or compose them programmatically.
Example:
# Place the operations on device "GPU:0" in the "ps" job.
device_spec = DeviceSpec(job="ps", device_type="GPU", device_index=0)
with tf.device(device_spec.to_string()):
# Both my_var and squared_var will be placed on /job:ps/device:GPU:0.
my_var = tf.Variable(..., name="my_variable")
squared_var = tf.square(my_var)
With eager execution disabled (by default in TensorFlow 1.x and by calling disable_eager_execution() in TensorFlow 2.x), the following syntax can be used:
tf.compat.v1.disable_eager_execution()
# Same as previous
device_spec = DeviceSpec(job="ps", device_type="GPU", device_index=0)
# No need of .to_string() method.
with tf.device(device_spec):
my_var = tf.Variable(..., name="my_variable")
squared_var = tf.square(my_var)
```
If a `DeviceSpec` is partially specified, it will be merged with other
`DeviceSpec`s according to the scope in which it is defined. `DeviceSpec`
components defined in inner scopes take precedence over those defined in
outer scopes.
```python
gpu0_spec = DeviceSpec(job="ps", device_type="GPU", device_index=0)
with tf.device(DeviceSpec(job="train").to_string()):
with tf.device(gpu0_spec.to_string()):
# Nodes created here will be assigned to /job:ps/device:GPU:0.
with tf.device(DeviceSpec(device_type="GPU", device_index=1).to_string()):
# Nodes created here will be assigned to /job:train/device:GPU:1.
A DeviceSpec consists of 5 components -- each of
which is optionally specified:
- Job: The job name.
- Replica: The replica index.
- Task: The task index.
- Device type: The device type string (e.g. "CPU" or "GPU").
- Device index: The device index.
Args | |
|---|---|
job
|
string. Optional job name. |
replica
|
int. Optional replica index. |
task
|
int. Optional task index. |
device_type
|
Optional device type string (e.g. "CPU" or "GPU") |
device_index
|
int. Optional device index. If left unspecified, device represents 'any' device_index. |
Attributes | |
|---|---|
device_index
|
|
device_type
|
|
job
|
|
replica
|
|
task
|
|
Methods
from_string
@classmethodfrom_string( spec )
Construct a DeviceSpec from a string.
| Args | |
|---|---|
spec
|
a string of the form
/job: |
| Returns | |
|---|---|
| A DeviceSpec. |
make_merged_spec
make_merged_spec(
dev
)
Returns a new DeviceSpec which incorporates dev.
When combining specs, dev will take precedence over the current spec.
So for instance:
first_spec = tf.DeviceSpec(job=0, device_type="CPU")
second_spec = tf.DeviceSpec(device_type="GPU")
combined_spec = first_spec.make_merged_spec(second_spec)
is equivalent to:
combined_spec = tf.DeviceSpec(job=0, device_type="GPU")
| Args | |
|---|---|
dev
|
a DeviceSpec
|
| Returns | |
|---|---|
A new DeviceSpec which combines self and dev
|
merge_from
merge_from(
dev
)
Merge the properties of "dev" into this DeviceSpec.
| Args | |
|---|---|
dev
|
a DeviceSpec.
|
parse_from_string
parse_from_string(
spec
)
Parse a DeviceSpec name into its components.
2.x behavior change: In TensorFlow 1.x, this function mutates its own state and returns itself. In 2.x, DeviceSpecs are immutable, and this function will return a DeviceSpec which contains the spec.
Recommended:
```
# my_spec and my_updated_spec are unrelated.
my_spec = tf.DeviceSpec.from_string("/CPU:0")
my_updated_spec = tf.DeviceSpec.from_string("/GPU:0")
with tf.device(my_updated_spec):
...
```
Will work in 1.x and 2.x (though deprecated in 2.x):
```
my_spec = tf.DeviceSpec.from_string("/CPU:0")
my_updated_spec = my_spec.parse_from_string("/GPU:0")
with tf.device(my_updated_spec):
...
```
Will NOT work in 2.x:
```
my_spec = tf.DeviceSpec.from_string("/CPU:0")
my_spec.parse_from_string("/GPU:0") # <== Will not update my_spec
with tf.device(my_spec):
...
```
In general, DeviceSpec.from_string should completely replace
DeviceSpec.parse_from_string, and DeviceSpec.replace should
completely replace setting attributes directly.
| Args | |
|---|---|
spec
|
an optional string of the form
/job: |
| Returns | |
|---|---|
The DeviceSpec.
|
| Raises | |
|---|---|
ValueError
|
if the spec was not valid. |
replace
replace(
**kwargs
)
Convenience method for making a new DeviceSpec by overriding fields.
For instance:
my_spec = DeviceSpec=(job="my_job", device="CPU")
my_updated_spec = my_spec.replace(device="GPU")
my_other_spec = my_spec.replace(device=None)
| Args | |
|---|---|
**kwargs
|
This method takes the same args as the DeviceSpec constructor |
| Returns | |
|---|---|
| A DeviceSpec with the fields specified in kwargs overridden. |
to_string
to_string()
Return a string representation of this DeviceSpec.
| Returns | |
|---|---|
|
a string of the form
/job: |
__eq__
__eq__(
other
)
Checks if the other DeviceSpec is same as the current instance, eg have
same value for all the internal fields.
| Args | |
|---|---|
other
|
Another DeviceSpec |
| Returns | |
|---|---|
Return True if other is also a DeviceSpec instance and has same value
as the current instance.
Return False otherwise.
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