python - 在 Python cProfile 中，调用计数和原始调用计数有什么区别？

Question

当我使用 pstats 显示分析数据时，第一列是每个函数的调用次数。

但是，当我对数据进行排序时，我可以在 calls、ncalls 和 pcalls 键之间进行选择。文档说 calls 和 ncalls 是调用计数，而 pcalls 是原始调用计数。按 calls 或 ncalls 排序是一样的吗？ pcalls 有什么不同？

Answer 1

http://docs.python.org/2/library/profile.html#module-cProfile

We define primitive to mean that the call was not induced via recursion.

...when the function does not recurse, these two values are the same

按calls 或ncalls 排序是一样的。

---

When there are two numbers in the first column (for example, 43/3), then the latter is the number of primitive calls, and the former is the actual number of calls. Note that when the function does not recurse, these two values are the same, and only the single figure is printed:

In [43]: def a(i):
   ....:     if i == 0:
   ....:         return
   ....:     a(i-1)
   ....:


In [54]: %prun a(0)
  ncalls  tottime  percall  cumtime  percall filename:lineno(function)
       1    0.000    0.000    0.000    0.000 <ipython-input-43-25b7f3d268b8>:1(a)


In [55]: %prun a(1)
  ncalls  tottime  percall  cumtime  percall filename:lineno(function)
     2/1    0.000    0.000    0.000    0.000 <ipython-input-43-25b7f3d268b8>:1(a)


In [56]: %prun a(3)
  ncalls  tottime  percall  cumtime  percall filename:lineno(function)
     4/1    0.000    0.000    0.000    0.000 <ipython-input-43-25b7f3d268b8>:1(a)