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[JIT][tracer] Sanity checks for tracing#10841

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[JIT][tracer] Sanity checks for tracing#10841
jamesr66a wants to merge 10 commits intopytorch:masterfrom
jamesr66a:trace_check

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@jamesr66a jamesr66a commented Aug 24, 2018

TODO: integrate into torch.onnx.export -- separate PR

Problem: We have a facility to trace PyTorch operations on Python code, but there are several failure modes where the trace is not representative of the actual underlying computation:

  • The tracer encountered dynamic control flow
  • Some computation escaped the tracer, and appeared as a Constant tensor node in the graph
  • Some stateful function was traced, e.g. someone did an optimization in Python by memoizing function outputs

Objective: In an ideal world, this whole process would be automated and the user can trust that the system will magically capture the intended semantics from the program. Realistically speaking, we will likely have to settle with a human-in-the-loop error reporting system, allowing for the user to identify problems and modify the source code to allow for tracing.

Stage 1 (this PR): Output-level checking & graph diff. torch.jit.trace gains a kwarg 'check_inputs', which is a list of tuples of input arguments. We will iterate through the list and trace the function again for each set of check inputs. We'll also interpret the original trace with these inputs and compare output values and graphs, printing a diff of the graph if there is a difference.

Examples:

@torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(4, 5),)])
def foo(x):
    y = torch.arange(0, x.shape[0]).float()
    return x + y.unsqueeze(1)
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		-   %1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
		?                                                              ^
		+   %1 : Dynamic = prim::Constant[value= 0  1  2  3 [ CPULongType{4} ]]()
		?                                                +++              ^
		    %2 : int = prim::Constant[value=0]()
		    %3 : Dynamic = aten::_cast_Float(%1, %2)
		    %4 : int = prim::Constant[value=1]()
		    %5 : Dynamic = aten::unsqueeze(%3, %4)
		    %6 : int = prim::Constant[value=1]()
		    %7 : Dynamic = aten::add(%0, %5, %6)
		    return (%7);
		  }
	Node diff:
		- %1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
		?                                                            ^
		+ %1 : Dynamic = prim::Constant[value= 0  1  2  3 [ CPULongType{4} ]]()
		?                                              +++              ^
	Trace source location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Check source location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(281): check_trace
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(408): wrapper
		dank.py(3): <module>
ERROR: Tensor-valued Constant nodes differed in value across invocations. This often indicates that the tracer has encountered untraceable code.
	Node:
		%1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
	Source Location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Comparison exception:
		Not equal to tolerance rtol=1e-07, atol=0

		(shapes (3,), (4,) mismatch)
		 x: array([0, 1, 2])
		 y: array([0, 1, 2, 3])

==

@torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])
def foo(x):
    y = x.data
    return x + y
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Tensor-valued Constant nodes differed in value across invocations. This often indicates that the tracer has encountered untraceable code.
	Node:
		%1 : Dynamic = prim::Constant[value=<Tensor>]()
	Source Location:
		dank.py(6): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Comparison exception:
		Not equal to tolerance rtol=1e-07, atol=0

		(mismatch 100.0%)
		 x: array([0.397137, 0.956105, 0.169478, 0.560292, 0.392568, 0.108441,
		       0.97645 , 0.34412 , 0.951246, 0.793061, 0.557595, 0.770245],
		      dtype=float32)
		 y: array([0.243178, 0.315964, 0.972041, 0.0215  , 0.927751, 0.457512,
		       0.951092, 0.97883 , 0.048688, 0.118066, 0.779345, 0.271272],
		      dtype=float32)

==

import torch

@torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(4, 4),)])
def foo(x):
    for _ in range(x.size(0)):
        x = torch.neg(x)
    return x
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		    %1 : Dynamic = aten::neg(%0)
		    %2 : Dynamic = aten::neg(%1)
		    %3 : Dynamic = aten::neg(%2)
		+   %4 : Dynamic = aten::neg(%3)
		-   return (%3);
		?            ^
		+   return (%4);
		?            ^
		  }

==

import torch

def foo(x):
    if not hasattr(foo, 'cache'):
        foo.cache = torch.neg(x)
    return x + foo.cache

traced = torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])(foo)
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		-   %1 : Dynamic = aten::neg(%0)
		+   %1 : Dynamic = prim::Constant[value=<Tensor>]()
		    %2 : int = prim::Constant[value=1]()
		    %3 : Dynamic = aten::add(%0, %1, %2)
		    return (%3);
		  }
	Node diff:
		- %1 : Dynamic = aten::neg(%0)
		+ %1 : Dynamic = prim::Constant[value=<Tensor>]()
	Trace source location:
		test.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		test.py(8): <module>
	Check source location:
		test.py(6): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(281): check_trace
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(408): wrapper
		test.py(8): <module>

The following two examples show instances where program semantics are lost in the Python -> trace transformation, and repeated invocation does not give us useful debug information. Further design in underway for catching these scenarios.

import torch

@torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])
def foo(x):
    for i in range(3):
        x[i, :] = torch.zeros(4)
    return x
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
Exception:
Not equal to tolerance rtol=1e-07, atol=0

(mismatch 100.0%)
 x: array([0.830221, 0.915481, 0.940281, 0.555241], dtype=float32)
 y: array([0., 0., 0., 0.], dtype=float32)

==

import torch

@torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(5, 6),)])
def foo(x):
    x.view(-1).add_(-x.view(-1))
    return x
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
Exception:
Not equal to tolerance rtol=1e-07, atol=0

(mismatch 100.0%)
 x: array([0.734441, 0.445327, 0.640592, 0.30076 , 0.891674, 0.124771],
      dtype=float32)
 y: array([0., 0., 0., 0., 0., 0.], dtype=float32)

@jamesr66a jamesr66a force-pushed the trace_check branch 4 times, most recently from 0f4a2cb to 538be05 Compare August 24, 2018 17:00
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@jamesr66a jamesr66a changed the title [WIP] Sanity checks for tracing [JIT][tracer] Sanity checks for tracing Aug 27, 2018
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%3 : Double(3, 5) = aten::mm(%0, %1), scope: TracedModule
%4 : Double(3, 7) = aten::mm(%3, %2), scope: TracedModule/TracedModule[TracedModule1][mod]
%5 : Long() = prim::Constant[value={1}](), scope: TracedModule
%5 : Double() = prim::Constant[value={1}](), scope: TracedModule

This comment was marked as off-topic.

@torch.jit.trace(torch.rand(3, 4))
def traced_fn(x):
return pm(x) + 1
return pm(x) + 1.0

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This comment was marked as off-topic.

test/test_jit.py Outdated
def foo(x):
return torch.dropout(x, p=0.5, train=False)

np.testing.assert_allclose(foo(input), input)

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if (kind() == aten::dropout && is_constant(attr::train) && !get<bool>(attr::train).value()) {
return false;
}
// batch_norm with training = False is deterministic

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} // namespace

bool Node::isNondeterministic() const {
if (nondeterminstic_aten_ops().count(kind()) == 0) {

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try:
mod_tensor_val = n_mod.t('value')
check_tensor_val = n_check.t('value')
except RuntimeError:

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tensor_compare_errors = None
# Check Tensor-valued constant nodes
for n_mod, n_check in zip(mod_canonicalized.nodes(), check_canonicalized.nodes()):
if n_mod.kind() == n_check.kind() and n_mod.kind() == 'prim::Constant':

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try:
traced_outs = wrap_non_iterable(module(*_clone_inputs(inputs)))
# TODO: multi-level nested compare of results.
traced_outs = [out for out in traced_outs if isinstance(out, torch.Tensor)]

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iter(x)
except TypeError:
x = [x]
return x

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check_inputs = kwargs.pop('check_inputs', None)
disable_checks = kwargs.pop('disable_checks', False)
check_tolerance = kwargs.pop('check_tolerance', 1e-7)

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I don't have additional things beside what Adam said except for nit.

We should consider setting the tolerance low enough that we don't cause anyone false positive. It would be a pretty bad experience to realize the only reason tracing failed was due to numeric nondeterminism.

void DecayTypes(const std::shared_ptr<Graph>& graph) {
for (Value * input : graph->inputs()) {
if (input->type()->cast<TensorType>()) {
input->setType(DynamicType::get());

This comment was marked as off-topic.

ss << n;
return ss.str();
})
.def("sourceLocation", [](Node & n) {

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std::stringstream ss;
if (auto sl = n.getSourceLocation())
sl->highlight(ss);
return ss.str();

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# Check the traced module against a set of user-provided validation inputs
def check_trace(check_inputs, func, executor_options, module, check_tolerance):

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def check_trace(check_inputs, func, executor_options, module, check_tolerance):
for inputs in check_inputs:
check_mod = TopLevelTracedModule(func, **executor_options)
check_mod._create_method_from_trace('forward', func, _clone_inputs(inputs))

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try:
mod_tensor_val = n_mod.t('value')
check_tensor_val = n_check.t('value')
except RuntimeError:

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check_inputs = kwargs.pop('check_inputs', None)
disable_checks = kwargs.pop('disable_checks', False)
check_tolerance = kwargs.pop('check_tolerance', 1e-7)

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@jamesr66a jamesr66a force-pushed the trace_check branch 3 times, most recently from addf644 to 4300eaf Compare August 27, 2018 23:52
@zou3519 zou3519 added oncall: jit Add this issue/PR to JIT oncall triage queue 0.3 labels Aug 28, 2018
@jamesr66a jamesr66a removed the 0.3 label Aug 28, 2018
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prim::NoneGenerator,
[](Node* node) {
return [](Stack& stack) {
stack.push_back(at::Tensor());

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except Exception as e:
msg = 'Encountered an exception while running checking trace with check inputs.\nException:\n' \
+ indent(str(e))
raise TracingCheckError(*graph_diagnostic_info(), extra_msg=msg)

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"aten::normal(Tensor mean, float std, *, Tensor generator) -> Tensor",
"aten::poisson(Tensor self, Tensor generator) -> Tensor",
"aten::rrelu(Tensor self, Scalar lower, Scalar upper, int training, Tensor generator) -> Tensor",
"aten::rrelu_with_noise(Tensor self, Tensor noise, Scalar lower, Scalar upper, int training, Tensor generator) -> Tensor"

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Probably should add aten::rand to the non-deterministic things. I am approving anyway so that it won't block landing.

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@pytorchbot retest this please

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PenghuiCheng pushed a commit to PenghuiCheng/pytorch that referenced this pull request Sep 11, 2018
Summary:
TODO: integrate into torch.onnx.export -- separate PR

*Problem:* We have a facility to trace PyTorch operations on Python code, but there are several failure modes where the trace is not representative of the actual underlying computation:

* The tracer encountered dynamic control flow
* Some computation escaped the tracer, and appeared as a Constant tensor node in the graph
* Some stateful function was traced, e.g. someone did an optimization in Python by memoizing function outputs

*Objective*: In an ideal world, this whole process would be automated and the user can trust that the system will magically capture the intended semantics from the program. Realistically speaking, we will likely have to settle with a human-in-the-loop error reporting system, allowing for the user to identify problems and modify the source code to allow for tracing.

*Stage 1* (this PR): Output-level checking & graph diff. torch.jit.trace gains a kwarg 'check_inputs', which is a list of tuples of input arguments. We will iterate through the list and trace the function again for each set of check inputs. We'll also interpret the original trace with these inputs and compare output values and graphs, printing a diff of the graph if there is a difference.

Examples:

```
torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(4, 5),)])
def foo(x):
    y = torch.arange(0, x.shape[0]).float()
    return x + y.unsqueeze(1)
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		-   %1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
		?                                                              ^
		+   %1 : Dynamic = prim::Constant[value= 0  1  2  3 [ CPULongType{4} ]]()
		?                                                +++              ^
		    %2 : int = prim::Constant[value=0]()
		    %3 : Dynamic = aten::_cast_Float(%1, %2)
		    %4 : int = prim::Constant[value=1]()
		    %5 : Dynamic = aten::unsqueeze(%3, %4)
		    %6 : int = prim::Constant[value=1]()
		    %7 : Dynamic = aten::add(%0, %5, %6)
		    return (%7);
		  }
	Node diff:
		- %1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
		?                                                            ^
		+ %1 : Dynamic = prim::Constant[value= 0  1  2  3 [ CPULongType{4} ]]()
		?                                              +++              ^
	Trace source location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Check source location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(281): check_trace
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(408): wrapper
		dank.py(3): <module>
ERROR: Tensor-valued Constant nodes differed in value across invocations. This often indicates that the tracer has encountered untraceable code.
	Node:
		%1 : Dynamic = prim::Constant[value= 0  1  2 [ CPULongType{3} ]]()
	Source Location:
		dank.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Comparison exception:
		Not equal to tolerance rtol=1e-07, atol=0

		(shapes (3,), (4,) mismatch)
		 x: array([0, 1, 2])
		 y: array([0, 1, 2, 3])

```
==

```
torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])
def foo(x):
    y = x.data
    return x + y
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Tensor-valued Constant nodes differed in value across invocations. This often indicates that the tracer has encountered untraceable code.
	Node:
		%1 : Dynamic = prim::Constant[value=<Tensor>]()
	Source Location:
		dank.py(6): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		dank.py(3): <module>
	Comparison exception:
		Not equal to tolerance rtol=1e-07, atol=0

		(mismatch 100.0%)
		 x: array([0.397137, 0.956105, 0.169478, 0.560292, 0.392568, 0.108441,
		       0.97645 , 0.34412 , 0.951246, 0.793061, 0.557595, 0.770245],
		      dtype=float32)
		 y: array([0.243178, 0.315964, 0.972041, 0.0215  , 0.927751, 0.457512,
		       0.951092, 0.97883 , 0.048688, 0.118066, 0.779345, 0.271272],
		      dtype=float32)
```

==

```
import torch

torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(4, 4),)])
def foo(x):
    for _ in range(x.size(0)):
        x = torch.neg(x)
    return x
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		    %1 : Dynamic = aten::neg(%0)
		    %2 : Dynamic = aten::neg(%1)
		    %3 : Dynamic = aten::neg(%2)
		+   %4 : Dynamic = aten::neg(%3)
		-   return (%3);
		?            ^
		+   return (%4);
		?            ^
		  }
```

==

```
import torch

def foo(x):
    if not hasattr(foo, 'cache'):
        foo.cache = torch.neg(x)
    return x + foo.cache

traced = torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])(foo)
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
ERROR: Graphs differed across invocations!
	Graph diff:
		  graph(%0 : Dynamic) {
		-   %1 : Dynamic = aten::neg(%0)
		+   %1 : Dynamic = prim::Constant[value=<Tensor>]()
		    %2 : int = prim::Constant[value=1]()
		    %3 : Dynamic = aten::add(%0, %1, %2)
		    return (%3);
		  }
	Node diff:
		- %1 : Dynamic = aten::neg(%0)
		+ %1 : Dynamic = prim::Constant[value=<Tensor>]()
	Trace source location:
		test.py(5): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(402): wrapper
		test.py(8): <module>
	Check source location:
		test.py(6): foo
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(281): check_trace
		/Users/jamesreed/onnx-fairseq/pytorch/torch/jit/__init__.py(408): wrapper
		test.py(8): <module>
```

The following two examples show instances where program semantics are lost in the Python -> trace transformation, and repeated invocation does not give us useful debug information. Further design in underway for catching these scenarios.

```
import torch

torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(3, 4),)])
def foo(x):
    for i in range(3):
        x[i, :] = torch.zeros(4)
    return x
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
Exception:
Not equal to tolerance rtol=1e-07, atol=0

(mismatch 100.0%)
 x: array([0.830221, 0.915481, 0.940281, 0.555241], dtype=float32)
 y: array([0., 0., 0., 0.], dtype=float32)
```

==

```
import torch

torch.jit.trace(torch.rand(3, 4), check_inputs=[(torch.rand(5, 6),)])
def foo(x):
    x.view(-1).add_(-x.view(-1))
    return x
```

```
torch.jit.TracingCheckError: Tracing failed sanity checks!
ERROR: Traced function outputs do not match the Python function outputs.
Exception:
Not equal to tolerance rtol=1e-07, atol=0

(mismatch 100.0%)
 x: array([0.734441, 0.445327, 0.640592, 0.30076 , 0.891674, 0.124771],
      dtype=float32)
 y: array([0., 0., 0., 0., 0., 0.], dtype=float32)
```
Pull Request resolved: pytorch#10841

Differential Revision: D9499945

Pulled By: jamesr66a

fbshipit-source-id: 1f842a32d0b0645259cc43b29700b86d99c59a45
@ezyang ezyang added the merged label Jun 26, 2019
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