导入Ray后出现内存泄漏求助：原因排查与报错消除方法

在使用Ray进行并行计算时遇到内存泄漏问题，将Python脚本简化为仅包含import ray和print("just a blank script")，仍出现内存泄漏报错（以下为部分日志，其余报错均与最后一条_PyEval_EvalFrameDefault相关）：

==8279== 54 bytes in 1 blocks are definitely lost in loss record 1,697 of 10,519
==8279==    at 0x4C30EDB: malloc (vg_replace_malloc.c:309)
==8279==    by 0x4F23592: PyObject_Malloc (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F5EAE9: PyUnicode_New (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F675F0: _PyUnicodeWriter_PrepareInternal (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F3806E: PyUnicode_DecodeUTF8Stateful (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F7A9F7: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F7AFFC: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F876AD: _Py_BuildValue_SizeT (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x40BA46D: PyInit_setproctitle (setproctitle.c:174)
==8279==    by 0x5053281: _PyImport_LoadDynamicModuleWithSpec (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x5053584: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FAF706: PyCFunction_Call (in /usr/lib64/libpython3.6m.so.1.0)
==8279== 
==8279== 56 bytes in 1 blocks are definitely lost in loss record 3,102 of 10,519
==8279==    at 0x4C30EDB: malloc (vg_replace_malloc.c:309)
==8279==    by 0x4F23592: PyObject_Malloc (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F3BB5C: _PyObject_GC_Malloc (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F4242D: _PyObject_GC_NewVar (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F5645E: PyTuple_New (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD85E8: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD8B18: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD872E: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD8B18: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD872E: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FD965C: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FDCAA0: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279== 
==8279== 64 bytes in 1 blocks are definitely lost in loss record 3,891 of 10,519
==8279==    at 0x4C30EDB: malloc (vg_replace_malloc.c:309)
==8279==    by 0x40141AD: dl_open_worker (in /usr/lib64/ld-2.28.so)
==8279==    by 0x5E79AB6: _dl_catch_exception (in /usr/lib64/libc-2.28.so)
==8279==    by 0x401365D: _dl_open (in /usr/lib64/ld-2.28.so)
==8279==    by 0x55B81B9: dlopen_doit (in /usr/lib64/libdl-2.28.so)
==8279==    by 0x5E79AB6: _dl_catch_exception (in /usr/lib64/libc-2.28.so)
==8279==    by 0x5E79B52: _dl_catch_error (in /usr/lib64/libc-2.28.so)
==8279==    by 0x55B8938: _dlerror_run (in /usr/lib64/libdl-2.28.so)
==8279==    by 0x55B8259: dlopen@@GLIBC_2.2.5 (in /usr/lib64/libdl-2.28.so)
==8279==    by 0x502DE19: _PyImport_FindSharedFuncptr (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x5053239: _PyImport_LoadDynamicModuleWithSpec (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x5053584: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279== 
==8279== 144 bytes in 1 blocks are definitely lost in loss record 7,610 of 10,519
==8279==    at 0x4C30EDB: malloc (vg_replace_malloc.c:309)
==8279==    by 0x4F23592: PyObject_Malloc (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FCF8B2: PyCode_New (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x89FE769: __pyx_pymod_exec__raylet(_object*) (in /root/.local/lib/python3.6/site-packages/ray/_raylet.so)
==8279==    by 0x502C2F2: PyModule_ExecDef (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x502C381: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FAF706: PyCFunction_Call (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FF3C41: _PyEval_EvalFrameDefault (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F3FBE7: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4F795DF: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FBDA31: ??? (in /usr/lib64/libpython3.6m.so.1.0)
==8279==    by 0x4FEDA69: _PyEval_EvalFrameDefault (in /usr/lib64/libpython3.6m.so.1.0)

使用以下命令进行内存测试：

PYTHONMALLOC=malloc valgrind --leak-check=full -v --track-origins=yes \
    --log-file=$SCRIPT_DIR"/algrind_pytest.log" \
    --show-possibly-lost=no \
    python test.py

环境信息：

• Python 3.6.8
• Valgrind 3.15.0
• Ray 1.12.1 / 2.3.1

通过heapy检测内存使用情况：

• 未导入Ray：4721167字节
• 导入Ray后：41986865字节
• 导入Ray后执行del ray和gc.collect()：仍为41984385字节

可见导入Ray后内存占用大幅增加，且删除模块无法释放内存。

诉求：

1. 了解该内存泄漏的原因
2. 若并非实际问题，如何消除Valgrind的报错信息

内容的提问来源于stack exchange，提问作者faked human mao