Fix a regression in handling processes that fork

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.13.2
+current_version = 1.13.3
 commit = True
 message = 
 	Prepare for {new_version} release

NEWS.rst

@@ -8,6 +8,15 @@ Changelog
 
 .. towncrier release notes start
 
+memray 1.13.3 (2024-07-02)
+--------------------------
+
+Bug Fixes
+~~~~~~~~~
+
+- Fix a bug that could result in truncated reports for applications that fork without calling :c:func:`PyOS_BeforeFork`, including by using `multiprocessing` with the "spawn" start method (the default on macOS). (#644)
+
+
 memray 1.13.2 (2024-06-27)
 --------------------------
 

src/memray/_memray.pyx

@@ -76,11 +76,17 @@ from ._metadata import Metadata
 from ._stats import Stats
 from ._thread_name_interceptor import ThreadNameInterceptor
 
-os.register_at_fork(
-    before=NativeTracker.prepareFork,
-    after_in_parent=NativeTracker.parentFork,
-    after_in_child=NativeTracker.childFork,
-)
+
+cdef extern from "pthread.h" nogil:
+    int pthread_atfork(void (*prepare)(), void (*parent)(), void (*child)())
+
+# NOTE: We can't reinitialize tracking in a child process until the interpreter
+#       has reinitialized its locks, so we do it in a Python fork handler.
+#       But, Python fork handlers aren't guaranteed to run for every fork, and
+#       the child process must never inherit an active tracker, so we must use
+#       a pthread fork handler to disable tracking before forking.
+pthread_atfork(&NativeTracker.prepareFork, &NativeTracker.parentFork, NULL)
+os.register_at_fork(after_in_child=NativeTracker.childFork)
 
 
 def set_log_level(int level):

src/memray/_memray/tracking_api.pxd

@@ -37,10 +37,10 @@ cdef extern from "tracking_api.h" namespace "memray::tracking_api":
         void registerThreadNameById(uint64_t, const char*) except+
 
         @staticmethod
-        void prepareFork() noexcept
+        void prepareFork() noexcept nogil
 
         @staticmethod
-        void parentFork() noexcept
+        void parentFork() noexcept nogil
 
         @staticmethod
-        void childFork() noexcept
+        void childFork() noexcept nogil

src/memray/_version.py

@@ -1 +1 @@
-__version__ = "1.13.2"
+__version__ = "1.13.3"