[pypy-dev] pypy callback function pointer become invalid

[Yicong Huang]

Hi,

We embeded Pypy in C++ code, and used the callback function pointer to
execute Python function.
And we noticed that, the callback function pointers might become invalid as
the memory usage grows.
Here is the piece of test code:

    for(int i = 0; i < LOOP; i++){
       //read python code from file
       char* pyBuffer = readPyFile("test_Lower.py");
       pypy_execute_source_ptr(pyBuffer, &ptr);
       callers[i] = ptr.pyPtrs[0];
    }
    //check 1st function pointer and call python function
    caller = callers[0];
    ret = (*((char *(*)(char *))caller))("A");
    printf("%s\n", ret);

In the experiment, if the LOOP >150, caller becomes invalid, the callback
to python function could not succed, and "Segmentation fault" error was
reported.
For more complex Python function, the valid LOOP might be smaller.

I am wondering whether the error was caused by GC in Pypy that recycled the
function pointers.
In python fill_api() code, I have used a gloabl list to append function
pointer, but it did not help.

#global list
no_gc = []
def fill_api(ptr):
   api = ffi.cast("struct pypyAPI*", ptr)
   api.pyPtrs[0] = test_Lower
   no_gc.append(api)
   no_gc.append(test_Lower)
   return api

And are there any methods to prevent such errors?
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