报错信息处理

本节内容将介绍使用动态图转静态图(下文简称:动转静)功能发生异常时,ProgramTranslator的动转静报错模块对报错信息做的处理,以帮助您更好地理解动转静报错信息。使用动转静功能运行动态图代码时,内部可以分为2个步骤:动态图代码转换成静态图代码,运行静态图代码。接下来将分别介绍这2个步骤中的异常报错情况。

动转静过程中的异常

在动态图代码转换成静态图代码的过程中,如果 ProgramTranslator 无法转换一个函数时,将会显示警告信息,并尝试直接运行该函数。 如下代码中,函数 inner_func 在调用前被转换成静态图代码,当 x = inner_func(data) 调用该函数时,不能重复转换,会给出警告信息:

import paddle
import numpy as np

@paddle.jit.to_static
def func():
    def inner_func(x):
        x_tensor = paddle.to_tensor(x)
        return x_tensor
    data = np.ones([3]).astype("int32")
    x = inner_func(data)
    return x
func()

ProgramTranslator打印的警告信息如下:

2020-01-01 00:00:00,104-WARNING: <function inner_func at 0x125b3a550> doesn't have to be transformed to static function because it has been transformed before, it will be run as-is.

运行转换后的代码报错

如果在动转静后的静态图代码中发生异常,ProgramTranslator 会捕获该异常,增强异常报错信息,将静态图代码报错行映射到转换前的动态图代码,并重新抛出该异常。 重新抛出的异常具有以下特点:

  • 隐藏了部分对用户无用的动转静过程调用栈;

  • 转换前的代码会给出提示:"In User Code:";

  • 报错信息中包含了转换前的原始动态图代码;

例如,运行以下代码,在静态图构建时,即编译期会抛出异常:

import paddle
import numpy as np

@paddle.jit.to_static
def func(x):
    x = paddle.to_tensor(x)
    x = paddle.reshape(x, shape=[-1, -1])
    return x

func(np.ones([3, 2]))

运行结果:

Traceback (most recent call last):
  <ipython-input-13-f9c3ea702e3a> in <module>()
     func(np.ones([3, 2]))
  File "paddle/fluid/dygraph/dygraph_to_static/program_translator.py", line 332, in __call__
    raise new_exception
AssertionError: In user code:

    File "<ipython-input-13-f9c3ea702e3a>", line 7, in func
        x = fluid.layers.reshape(x, shape=[-1, -1])
    File "paddle/fluid/layers/nn.py", line 6193, in reshape
        attrs["shape"] = get_attr_shape(shape)
    File "paddle/fluid/layers/nn.py", line 6169, in get_attr_shape
        "be -1. But received shape[%d] is also -1." % dim_idx)
    AssertionError: Only one dimension value of 'shape' in reshape can be -1. But received shape[1] is also -1.

上述报错信息可以分为3点:

  1. 报错栈中,涉及代码转换过程的信息栈默认会被隐藏,不进行展示,以减少干扰信息。

  2. ProgramTranslator 处理后的报错信息中,会包含提示 "In user code:",表示之后的报错栈中,包含动转静前的动态图代码,即用户写的代码:

    AssertionError: In user code:
    
        File "<ipython-input-13-f9c3ea702e3a>", line 7, in func
           x = fluid.layers.reshape(x, shape=[-1, -1])
        File "paddle/fluid/layers/nn.py", line 6193, in reshape
            attrs["shape"] = get_attr_shape(shape)
        File "paddle/fluid/layers/nn.py", line 6169, in get_attr_shape
            "be -1. But received shape[%d] is also -1." % dim_idx)
    

    其中,File "<ipython-input-13-f9c3ea702e3a>", line 7, in func 是转换前的代码位置信息,x = fluid.layers.reshape(x, shape=[-1, -1]) 是转换前的代码。

  3. 新的异常中,包含原始报错中的的报错信息,如下:

    AssertionError: Only one dimension value of 'shape' in reshape can be -1. But received shape[1] is also -1.
    

注解:

如果您想查看 Paddle 原生报错信息栈,即未被动转静模块处理过的报错信息栈,可以设置环境变量 TRANSLATOR_DISABLE_NEW_ERROR=1 关闭动转静报错模块。该环境变量默认值为0,表示默认开启动转静报错模块。

运行以下代码,在静态图运行期会抛出异常:

@paddle.jit.to_static
def func(x):
    x = paddle.to_tensor(x)
    two = paddle.fill_constant(shape=[1], value=2, dtype="int32")
    x = paddle.reshape(x, shape=[1, two])
    return x

func(np.ones([3]).astype("int32"))

运行结果:

Traceback (most recent call last):
  File "<ipython-input-57-c63d6a351262>", line 10, in <module>()
     func(np.ones([3]).astype("int32"))
  File "paddle/fluid/dygraph/dygraph_to_static/program_translator.py", line 332, in __call__
    raise new_exception

EnforceNotMet: In user code:

    File "<ipython-input-57-c63d6a351262>", line 7, in func
      x = paddle.reshape(x, shape=[1, two])
    File "paddle/tensor/manipulation.py", line 1347, in reshape
      return paddle.fluid.layers.reshape(x=x, shape=shape, name=name)
    File "paddle/fluid/layers/nn.py", line 6209, in reshape
      "XShape": x_shape})
    File "paddle/fluid/layer_helper.py", line 43, in append_op
      return self.main_program.current_block().append_op(*args, **kwargs)
    File "paddle/fluid/framework.py", line 2880, in append_op
      attrs=kwargs.get("attrs", None))
    File "paddle/fluid/framework.py", line 1977, in __init__
      for frame in traceback.extract_stack():

--------------------------------------
C++ Traceback (most recent call last):
--------------------------------------
0   paddle::imperative::Tracer::TraceOp(std::string const&, paddle::imperative::NameVarBaseMap const&, paddle::imperative::NameVarBaseMap const&, paddle::framework::AttributeMap, paddle::platform::Place const&, bool)
1   paddle::imperative::OpBase::Run(paddle::framework::OperatorBase const&, paddle::imperative::NameVarBaseMap const&, paddle::imperative::NameVarBaseMap const&, paddle::framework::AttributeMap const&, paddle::platform::Place const&)
2   paddle::imperative::PreparedOp::Run(paddle::imperative::NameVarBaseMap const&, paddle::imperative::NameVarBaseMap const&, paddle::framework::AttributeMap const&)
3   std::_Function_handler<void (paddle::framework::ExecutionContext const&), paddle::framework::OpKernelRegistrarFunctor<paddle::platform::CPUPlace, false, 0ul, paddle::operators::RunProgramOpKernel<paddle::platform::CPUDeviceContext, float> >::operator()(char const*, char const*, int) const::{lambda(paddle::framework::ExecutionContext const&)#1}>::_M_invoke(std::_Any_data const&, paddle::framework::ExecutionContext const&)
4   paddle::operators::RunProgramOpKernel<paddle::platform::CPUDeviceContext, float>::Compute(paddle::framework::ExecutionContext const&) const
5   paddle::framework::Executor::RunPartialPreparedContext(paddle::framework::ExecutorPrepareContext*, paddle::framework::Scope*, long, long, bool, bool, bool)
6   paddle::framework::OperatorBase::Run(paddle::framework::Scope const&, paddle::platform::Place const&)
7   paddle::framework::OperatorWithKernel::RunImpl(paddle::framework::Scope const&, paddle::platform::Place const&) const
8   paddle::framework::OperatorWithKernel::RunImpl(paddle::framework::Scope const&, paddle::platform::Place const&, paddle::framework::RuntimeContext*) const
9   paddle::operators::ReshapeKernel::operator()(paddle::framework::ExecutionContext const&) const
10  paddle::operators::ReshapeOp::ValidateShape(std::vector<int, std::allocator<int> >, paddle::framework::DDim const&)
11  paddle::platform::EnforceNotMet::EnforceNotMet(std::string const&, char const*, int)
12  paddle::platform::GetCurrentTraceBackString()

----------------------
Error Message Summary:
----------------------
InvalidArgumentError: The 'shape' in ReshapeOp is invalid. The input tensor X'size must be equal to the capacity of 'shape'. But received X's shape = [3], X's size = 3, 'shape' is [1, 2], the capacity of 'shape' is 2.
  [Hint: Expected capacity == in_size, but received capacity:2 != in_size:3.] (at /paddle/paddle/fluid/operators/reshape_op.cc:206)
  [operator < reshape2 > error]  [operator < run_program > error]

上述异常中,除了隐藏部分报错栈、报错定位到转换前的动态图代码外,报错信息中包含了C++报错栈 C++ TracebackError Message Summary,这是 Paddle 的 C++ 端异常信息,经处理后在 Python 的异常信息中显示。

注解:

如果您想查看被隐藏的信息栈,可以设置环境变量 TRANSLATOR_SIMPLIFY_NEW_ERROR=0。该环境变量默认值为1,表示隐藏冗余的报错信息栈。