# 报错RuntimeError:Exceed function call depth limit 1000

**1. 报错描述**

1.1 系统环境

```
Hardware Environment(Ascend/GPU/CPU): Ascend
Software Environment:
-- MindSpore version (source or binary): 1.6.0
-- Python version (e.g., Python 3.7.5): 3.7.6
-- OS platform and distribution (e.g., Linux Ubuntu 16.04): Ubuntu 4.15.0-74-generic
-- GCC/Compiler version (if compiled from source):
```

1.2 基本信息

1.2.1 脚本

训练脚本是通过构建Concat单算子网络，在特定的轴连接张量的例子。脚本如下：

```
 1 context.set_context(mode=context.GRAPH_MODE, device_target=&quot;Ascend&quot;)
 2 class Net(nn.Cell):
 3   def __init__(self):
 4     super(Net, self).__init__()
 5     self.concat = ops.Concat()
 6
 7   def construct(self, x):
 8     n = 1000
 9     input_x = ()
 10     for i in range(n):
 11       input_x += (x,)
 12     output = self.concat(input_x)
 13     return output
 14
 15 net = Net()
 16 input_x1 = Tensor(np.random.rand(1, 4, 16, 16), mindspore.float32)
 17 output = net(input_x1)
 18 print(f"输出结果：{output.shape}")
```

报错

这里报错信息如下：

```
Traceback (most recent call last):
 File &quot;demo.py&quot;, line 17, in &lt;module&gt;
  output = net(input_x1)
 File &quot; /lib/python3.7/site-packages/mindspore/nn/cell.py&quot;, line 542, in __call__
  out = self.compile_and_run(*args)
 File &quot; lib/python3.7/site-packages/mindspore/nn/cell.py&quot;, line 872, in compile_and_run
  self.compile(*inputs)
 File &quot;/lib/python3.7/site-packages/mindspore/nn/cell.py&quot;, line 857, in compile
  _cell_graph_executor.compile(self, *inputs, phase=self.phase, auto_parallel_mode=self._auto_parallel_mode)
 File &quot;/lib/python3.7/site-packages/mindspore/common/api.py&quot;, line 712, in compile
  result = self._graph_executor.compile(obj, args_list, phase, self._use_vm_mode())
RuntimeError: mindspore/ccsrc/pipeline/jit/static_analysis/evaluator.cc:100 EnterStackFrame] Exceed function call depth limit 1000, (function call depth: 1001, simulate call depth: 999).
It's always happened with complex construction of code or infinite recursion or loop.
Please check the code if it's has the infinite recursion or call 'context.set_context(max_call_depth=value)' to adjust this value.
If max_call_depth is set larger, the system max stack depth should be set larger too to avoid stack overflow.
For more details, please refer to the FAQ at https://www.mindspore.cn.
The function call stack (See file 'demo/rank_0/om/analyze_fail.dat' for more details):
\# 0 In file demo.py(10)
​    for i in range(n):
\# 1 In file /lib/python3.7/site-packages/mindspore/_extends/parse/standard_method.py(1441)
  return it.__ms_hasnext__()
​      
\# 2 In file /lib/python3.7/site-packages/mindspore/_extends/parse/standard_method.py(1860)
  return len(xs) &gt; 0
```

原因分析

我们看报错信息，在RuntimeError中，写到Exceed function call depth limit 1000, \(function call depth: 1001, simulate call depth: 999\)，意思是超过函数调用深度限制1000，\(函数调用深度:1001，模拟调用深度:999\)，这是由于函数默认调用最大限度设置为1000，继续看报错信息，写到Please check the code if it's has the infinite recursion or call 'context.set\_context\(max\_call\_depth=value\)' to adjust this value，即检查代码是否存在无限递归计算，或者调用\*\*context.set\_context\(max\_call\_depth=value\)\*\*，调整函数深度限制的默认设置。

**2. 解决方法**

基于上面已知的原因，很容易做出如下修改：

```
 1 context.set_context(mode=context.GRAPH_MODE, max_call_depth=20000,device_target=&quot;Ascend&quot;)
 2 class Net(nn.Cell):
 3   def __init__(self):
 4     super(Net, self).__init__()
 5     self.concat = ops.Concat()
 6
 7   def construct(self, x):
 8     n = 1000
 9     input_x = ()
 10     for i in range(n):
 11       input_x += (x,)
 12     output = self.concat(input_x)
 13     return output
 14
 15 net = Net()
 16 input_x1 = Tensor(np.random.rand(1, 196, 80, 38), mindspore.float32)
 17 output = net(input_x1)
 18 print(f"输出结果：{output.shape}")
```

此时执行成功，输出如下：

输出结果：\(1000, 196, 80, 38\)

**3. 总结**

定位报错问题的步骤：

1、 找到报错的用户代码行：output = net\(input\_x1\);

2、 根据日志报错信息中的关键字，缩小分析问题的范围: Exceed function call depth limit 1000, \(function call depth: 1001, simulate call depth: 999\);

3、 根据报错提示信息进行修改默认设置，call 'context.set\_context\(max\_call\_depth=value\)' to adjust this value；

4、 需要重点关注变量定义、初始化的正确性。

**4. 参考文档**

4.1  [Concat算子API接口](https://www.mindspore.cn/docs/api/zh-CN/r1.6/api_python/ops/mindspore.ops.Concat.html?highlight=concat)

