bpo-36142: PYTHONMALLOC overrides PYTHONDEV (pythonGH-12191)

bpo-34247, bpo-36142: The PYTHONMALLOC environment variable has the priority over PYTHONDEV env var and "-X dev" command line option. For example, PYTHONMALLOC=malloc PYTHONDEVMODE=1 sets the memory allocators to "malloc" (and not to "debug"). Add an unit test.

Author: vstinner

Lib/test/test_embed.py

@@ -524,7 +524,7 @@ def test_init_from_config(self):
  'install_signal_handlers': 0,
  'use_hash_seed': 1,
  'hash_seed': 123,
- 'allocator': 'malloc_debug',
+ 'allocator': 'malloc',
  'tracemalloc': 2,
  'import_time': 1,
  'show_ref_count': 1,
@@ -564,7 +564,7 @@ def test_init_from_config(self):
  INIT_ENV_CONFIG = {
  'use_hash_seed': 1,
  'hash_seed': 42,
- 'allocator': 'malloc_debug',
+ 'allocator': 'malloc',
  'tracemalloc': 2,
  'import_time': 1,
  'malloc_stats': 1,
@@ -592,6 +592,12 @@ def test_init_env_dev_mode(self):
  dev_mode=1)
  self.check_config("init_env_dev_mode", config)
 
+ def test_init_env_dev_mode(self):
+ config = dict(self.INIT_ENV_CONFIG,
+ allocator='malloc',
+ dev_mode=1)
+ self.check_config("init_env_dev_mode_alloc", config)
+
  def test_init_dev_mode(self):
  config = {
  'dev_mode': 1,

Programs/_testembed.c

@@ -442,8 +442,8 @@ static int test_init_from_config(void)
  config.use_hash_seed = 1;
  config.hash_seed = 123;
 
- putenv("PYTHONMALLOC=malloc");
- config.preconfig.allocator = "malloc_debug";
+ putenv("PYTHONMALLOC=malloc_debug");
+ config.preconfig.allocator = "malloc";
 
  /* dev_mode=1 is tested in test_init_dev_mode() */
 
@@ -570,7 +570,7 @@ static int test_init_from_config(void)
 static void test_init_env_putenvs(void)
 {
  putenv("PYTHONHASHSEED=42");
- putenv("PYTHONMALLOC=malloc_debug");
+ putenv("PYTHONMALLOC=malloc");
  putenv("PYTHONTRACEMALLOC=2");
  putenv("PYTHONPROFILEIMPORTTIME=1");
  putenv("PYTHONMALLOCSTATS=1");
@@ -594,32 +594,45 @@ static void test_init_env_putenvs(void)
 }
 
 
+static int test_init_env(void)
+{
+ /* Test initialization from environment variables */
+ Py_IgnoreEnvironmentFlag = 0;
+ test_init_env_putenvs();
+ _testembed_Py_Initialize();
+ dump_config();
+ Py_Finalize();
+ return 0;
+}
+
+
 static void test_init_env_dev_mode_putenvs(void)
 {
  test_init_env_putenvs();
- putenv("PYTHONMALLOC=malloc");
+ putenv("PYTHONMALLOC=");
  putenv("PYTHONFAULTHANDLER=");
  putenv("PYTHONDEVMODE=1");
 }
 
 
-static int test_init_env(void)
+static int test_init_env_dev_mode(void)
 {
  /* Test initialization from environment variables */
  Py_IgnoreEnvironmentFlag = 0;
- test_init_env_putenvs();
+ test_init_env_dev_mode_putenvs();
  _testembed_Py_Initialize();
  dump_config();
  Py_Finalize();
  return 0;
 }
 
 
-static int test_init_env_dev_mode(void)
+static int test_init_env_dev_mode_alloc(void)
 {
  /* Test initialization from environment variables */
  Py_IgnoreEnvironmentFlag = 0;
  test_init_env_dev_mode_putenvs();
+ putenv("PYTHONMALLOC=malloc");
  _testembed_Py_Initialize();
  dump_config();
  Py_Finalize();
@@ -700,6 +713,7 @@ static struct TestCase TestCases[] = {
  { "init_from_config", test_init_from_config },
  { "init_env", test_init_env },
  { "init_env_dev_mode", test_init_env_dev_mode },
+ { "init_env_dev_mode_alloc", test_init_env_dev_mode_alloc },
  { "init_dev_mode", test_init_dev_mode },
  { "init_isolated", test_init_isolated },
  { NULL, NULL }

Python/preconfig.c

@@ -445,14 +445,11 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
  }
 
  /* allocator */
- if (config->dev_mode && config->allocator == NULL) {
- config->allocator = _PyMem_RawStrdup("debug");
- if (config->allocator == NULL) {
- return _Py_INIT_NO_MEMORY();
- }
- }
-
  if (config->allocator == NULL) {
+ /* bpo-34247. The PYTHONMALLOC environment variable has the priority
+ over PYTHONDEV env var and "-X dev" command line option.
+ For example, PYTHONMALLOC=malloc PYTHONDEVMODE=1 sets the memory
+ allocators to "malloc" (and not to "debug"). */
  const char *allocator = _PyPreConfig_GetEnv(config, "PYTHONMALLOC");
  if (allocator) {
  config->allocator = _PyMem_RawStrdup(allocator);
@@ -462,6 +459,13 @@ preconfig_read(_PyPreConfig *config, const _PyPreCmdline *cmdline)
  }
  }
 
+ if (config->dev_mode && config->allocator == NULL) {
+ config->allocator = _PyMem_RawStrdup("debug");
+ if (config->allocator == NULL) {
+ return _Py_INIT_NO_MEMORY();
+ }
+ }
+
  assert(config->coerce_c_locale >= 0);
  assert(config->utf8_mode >= 0);
  assert(config->isolated >= 0);