Memory scheduling priority counting children #12
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… stuck with producers and 2 is when consumers are dependent on multiple objects
… calling taskblock callback twice
…wang/ray into memory-scheduling-jae
stephanie-wang
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Aug 5, 2022
We encountered SIGSEGV when running Python test `python/ray/tests/test_failure_2.py::test_list_named_actors_timeout`. The stack is: ``` #0 0x00007fffed30f393 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string const&) () from /lib64/libstdc++.so.6 #1 0x00007fffee707649 in ray::RayLog::GetLoggerName() () from /home/admin/dev/Arc/merge/ray/python/ray/_raylet.so #2 0x00007fffee70aa90 in ray::SpdLogMessage::Flush() () from /home/admin/dev/Arc/merge/ray/python/ray/_raylet.so #3 0x00007fffee70af28 in ray::RayLog::~RayLog() () from /home/admin/dev/Arc/merge/ray/python/ray/_raylet.so #4 0x00007fffee2b570d in ray::asio::testing::(anonymous namespace)::DelayManager::Init() [clone .constprop.0] () from /home/admin/dev/Arc/merge/ray/python/ray/_raylet.so #5 0x00007fffedd0d95a in _GLOBAL__sub_I_asio_chaos.cc () from /home/admin/dev/Arc/merge/ray/python/ray/_raylet.so #6 0x00007ffff7fe282a in call_init.part () from /lib64/ld-linux-x86-64.so.2 #7 0x00007ffff7fe2931 in _dl_init () from /lib64/ld-linux-x86-64.so.2 #8 0x00007ffff7fe674c in dl_open_worker () from /lib64/ld-linux-x86-64.so.2 #9 0x00007ffff7b82e79 in _dl_catch_exception () from /lib64/libc.so.6 #10 0x00007ffff7fe5ffe in _dl_open () from /lib64/ld-linux-x86-64.so.2 #11 0x00007ffff7d5f39c in dlopen_doit () from /lib64/libdl.so.2 #12 0x00007ffff7b82e79 in _dl_catch_exception () from /lib64/libc.so.6 #13 0x00007ffff7b82f13 in _dl_catch_error () from /lib64/libc.so.6 #14 0x00007ffff7d5fb09 in _dlerror_run () from /lib64/libdl.so.2 #15 0x00007ffff7d5f42a in dlopen@@GLIBC_2.2.5 () from /lib64/libdl.so.2 #16 0x00007fffef04d330 in py_dl_open (self=<optimized out>, args=<optimized out>) at /tmp/python-build.20220507135524.257789/Python-3.7.11/Modules/_ctypes/callproc.c:1369 ``` The root cause is that when loading `_raylet.so`, `static DelayManager _delay_manager` is initialized and `RAY_LOG(ERROR) << "RAY_testing_asio_delay_us is set to " << delay_env;` is executed. However, the static variables declared in `logging.cc` are not initialized yet (in this case, `std::string RayLog::logger_name_ = "ray_log_sink"`). It's better not to rely on the initialization order of static variables in different compilation units because it's not guaranteed. I propose to change all `RAY_LOG`s to `std::cerr` in `DelayManager::Init()`. The crash happens in Ant's internal codebase. Not sure why this test case passes in the community version though. BTW, I've tried different approaches: 1. Using a static local variable in `get_delay_us` and remove the global variable. This doesn't work because `init()` needs to access the variable as well. 2. Defining the global variable as type `std::unique_ptr<DelayManager>` and initialize it in `get_delay_us`. This works but it requires a lock to be thread-safe.
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Why are these changes needed?
There are two major changes.
two phase priority assignment.
When a priority is first assigned to a task, assign its id from childless_id (monotonically increase from 10000)
If a consumer task is submitted, the depending producer task is assigned a new id from id (start from 0)
This way we prioritize producers with consumers submitted and start DFS from those tasks.
1.1 Added pop_back() after extend() as extend() in priority modifies the priority.
Pointer in task priority managing from core_worker/reference_counter to have the priority change to take effect and remove copying overhead. Since the priority change after first consumer is submitted, we should point to the same priority instead of copying values
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