Clean Up nogil Warning From Parsers (#30369)

Author: WillAyd

pandas/_libs/parsers.pyx

@@ -171,12 +171,9 @@ cdef extern from "parser/tokenizer.h":
  int64_t skip_first_N_rows
  int64_t skipfooter
  # pick one, depending on whether the converter requires GIL
- float64_t (*double_converter_nogil)(const char *, char **,
- char, char, char,
- int, int *, int *) nogil
- float64_t (*double_converter_withgil)(const char *, char **,
- char, char, char,
- int, int *, int *)
+ float64_t (*double_converter)(const char *, char **,
+ char, char, char,
+ int, int *, int *) nogil
 
  # error handling
  char *warn_msg
@@ -469,16 +466,11 @@ cdef class TextReader:
 
  if float_precision == "round_trip":
  # see gh-15140
- #
- # Our current roundtrip implementation requires the GIL.
- self.parser.double_converter_nogil = NULL
- self.parser.double_converter_withgil = round_trip
+ self.parser.double_converter = round_trip
  elif float_precision == "high":
- self.parser.double_converter_withgil = NULL
- self.parser.double_converter_nogil = precise_xstrtod
+ self.parser.double_converter = precise_xstrtod
  else:
- self.parser.double_converter_withgil = NULL
- self.parser.double_converter_nogil = xstrtod
+ self.parser.double_converter = xstrtod
 
  if isinstance(dtype, dict):
  dtype = {k: pandas_dtype(dtype[k])
@@ -1663,22 +1655,12 @@ cdef _try_double(parser_t *parser, int64_t col,
  result = np.empty(lines, dtype=np.float64)
  data = <float64_t *>result.data
  na_fset = kset_float64_from_list(na_flist)
- if parser.double_converter_nogil != NULL: # if it can run without the GIL
- with nogil:
- error = _try_double_nogil(parser, parser.double_converter_nogil,
- col, line_start, line_end,
- na_filter, na_hashset, use_na_flist,
- na_fset, NA, data, &na_count)
- else:
- assert parser.double_converter_withgil != NULL
- error = _try_double_nogil(parser,
- <float64_t (*)(const char *, char **,
- char, char, char,
- int, int *, int *)
- nogil>parser.double_converter_withgil,
+ with nogil:
+ error = _try_double_nogil(parser, parser.double_converter,
  col, line_start, line_end,
  na_filter, na_hashset, use_na_flist,
  na_fset, NA, data, &na_count)
+
  kh_destroy_float64(na_fset)
  if error != 0:
  return None, None

pandas/_libs/src/parser/tokenizer.c

@@ -1774,11 +1774,18 @@ double precise_xstrtod(const char *str, char **endptr, char decimal,
 
 double round_trip(const char *p, char **q, char decimal, char sci, char tsep,
  int skip_trailing, int *error, int *maybe_int) {
+ // This is called from a nogil block in parsers.pyx
+ // so need to explicitly get GIL before Python calls
+ PyGILState_STATE gstate;
+ gstate = PyGILState_Ensure();
+
  double r = PyOS_string_to_double(p, q, 0);
  if (maybe_int != NULL) *maybe_int = 0;
  if (PyErr_Occurred() != NULL) *error = -1;
  else if (r == Py_HUGE_VAL) *error = (int)Py_HUGE_VAL;
  PyErr_Clear();
+
+ PyGILState_Release(gstate);
  return r;
 }
 

pandas/_libs/src/parser/tokenizer.h

@@ -155,11 +155,8 @@ typedef struct parser_t {
  PyObject *skipfunc;
  int64_t skip_first_N_rows;
  int64_t skip_footer;
- // pick one, depending on whether the converter requires GIL
- double (*double_converter_nogil)(const char *, char **,
- char, char, char, int, int *, int *);
- double (*double_converter_withgil)(const char *, char **,
- char, char, char, int, int *, int *);
+ double (*double_converter)(const char *, char **,
+ char, char, char, int, int *, int *);
 
  // error handling
  char *warn_msg;
@@ -226,6 +223,8 @@ double xstrtod(const char *p, char **q, char decimal, char sci, char tsep,
 double precise_xstrtod(const char *p, char **q, char decimal,
  char sci, char tsep, int skip_trailing,
  int *error, int *maybe_int);
+
+// GH-15140 - round_trip requires and acquires the GIL on its own
 double round_trip(const char *p, char **q, char decimal, char sci, char tsep,
  int skip_trailing, int *error, int *maybe_int);
 int to_boolean(const char *item, uint8_t *val);