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#include <torch/csrc/distributed/rpc/python_rpc_handler.h>
#include <torch/csrc/distributed/rpc/rpc_agent.h>
#include <torch/csrc/jit/python/pybind_utils.h>
#include <torch/csrc/utils/python_compat.h>
namespace torch {
namespace distributed {
namespace rpc {
namespace {
constexpr auto kInternalModule = "torch.distributed.rpc.internal";
// A macro that grabs the GIL, profiling the acquisition time. The average GIL
// acquisition time will be recorded in RpcAgent's getMetrics().
#define PROFILE_GIL_SCOPED_ACQUIRE \
std::chrono::time_point<std::chrono::high_resolution_clock> startTime; \
auto shouldProfileGIL = \
RpcAgent::getCurrentRpcAgent()->isGILProfilingEnabled(); \
if (shouldProfileGIL) { \
startTime = std::chrono::high_resolution_clock::now(); \
} \
pybind11::gil_scoped_acquire ag; \
if (shouldProfileGIL) { \
auto dur = std::chrono::duration_cast<std::chrono::microseconds>( \
std::chrono::high_resolution_clock::now() - startTime); \
RpcAgent::getCurrentRpcAgent()->addGilWaitTime(dur); \
} // NOLINT
// PythonTypeResolver that inherits from Script::Resolver to
// support resolving types together with ScriptTypeParser.
struct PythonTypeResolver : public jit::Resolver {
std::shared_ptr<jit::SugaredValue> resolveValue(
const std::string& /* unused */,
torch::jit::GraphFunction& /* unused */,
const jit::SourceRange& /* unused */) override {
TORCH_INTERNAL_ASSERT(
false, "RPC Type resolver does not need to resolve value");
}
TypePtr resolveType(
const std::string& name,
const jit::SourceRange& /* unused */) override {
if (name == "PyObject") {
return PyObjectType::get();
}
return PythonRpcHandler::getInstance().jitCompilationUnit()->get_type(name);
}
};
py::object getFunction(const py::object& module, const char* name) {
py::object fn = module.attr(name);
TORCH_CHECK(
py::isinstance<py::function>(fn),
"attribute ",
name,
" is not a function");
return fn;
}
void cleanupPyObj(py::object& obj) {
obj.dec_ref();
// explicitly setting PyObject* to nullptr to prevent py::object's dtor to
// decref on the PyObject again.
// See Note [Destructing py::object] in python_ivalue.h
obj.ptr() = nullptr;
}
} // namespace
void PythonRpcHandler::init() {
std::lock_guard<std::mutex> guard(init_lock_);
if (!initialized_) {
PROFILE_GIL_SCOPED_ACQUIRE;
py::object rpcInternal = py::module::import(kInternalModule);
py::object rpcApi = py::module::import("torch.distributed.rpc.api");
py::object rrefProxy =
py::module::import("torch.distributed.rpc.rref_proxy");
pyRunFunction_ = getFunction(rpcInternal, "_run_function");
pySerialize_ = getFunction(rpcInternal, "serialize");
pyDeserialize_ = getFunction(rpcInternal, "deserialize");
pyHandleException_ = getFunction(rpcInternal, "_handle_exception");
rrefTypeFunctions_.onOwner_ = getFunction(rpcApi, "_rref_typeof_on_owner");
rrefTypeFunctions_.onUser_ = getFunction(rpcApi, "_rref_typeof_on_user");
rrefProxyFunctions_.rpcSync_ = getFunction(rpcApi, "rpc_sync");
rrefProxyFunctions_.rpcAsync_ = getFunction(rpcApi, "rpc_async");
rrefProxyFunctions_.remote_ = getFunction(rpcApi, "remote");
rrefProxyFunctions_.rrefProxyCtor_ = getFunction(rrefProxy, "RRefProxy");
jitCompilationUnit_ = torch::jit::get_python_cu();
typeParser_ = std::make_shared<jit::ScriptTypeParser>(
std::make_shared<PythonTypeResolver>());
initialized_ = true;
}
}
PythonRpcHandler::PythonRpcHandler() : initialized_(false) {}
void PythonRpcHandler::cleanup() {
std::lock_guard<std::mutex> guard(init_lock_);
PROFILE_GIL_SCOPED_ACQUIRE;
cleanupPyObj(pyRunFunction_);
cleanupPyObj(pySerialize_);
cleanupPyObj(pyDeserialize_);
cleanupPyObj(pyHandleException_);
cleanupPyObj(rrefProxyFunctions_.rpcSync_);
cleanupPyObj(rrefProxyFunctions_.rpcAsync_);
cleanupPyObj(rrefProxyFunctions_.remote_);
cleanupPyObj(rrefProxyFunctions_.rrefProxyCtor_);
jitCompilationUnit_ = nullptr;
typeParser_ = nullptr;
initialized_ = false;
}
PythonRpcHandler& PythonRpcHandler::getInstance() {
// A thread could hold GIL when calling PythonRpcHandler::getInstance(),
// meantime another thread could have been doing static data
// initialization by calling `new PythonRpcHandler()`, inside of which GIL is
// also required. Static data initialization is thread-safe, so the thread
// holding the GIL will wait for the other thread to finish static data
// initializating before going forward. Because the initialization can't
// proceed without GIL, there is a deadlock. We ask the calling thread to
// release GIL to avoid this situation.
TORCH_INTERNAL_ASSERT(!PyGILState_Check());
// Leaky singleton to avoid module destructor race.
static PythonRpcHandler* handler = new PythonRpcHandler();
handler->init();
return *handler;
}
std::shared_ptr<torch::jit::CompilationUnit> PythonRpcHandler::
jitCompilationUnit() {
return jitCompilationUnit_;
}
py::object PythonRpcHandler::runPythonUdf(const py::object& pythonUdf) {
PROFILE_GIL_SCOPED_ACQUIRE;
// Throw a descriptive error message if pyRunFunction_ is already cleaned up.
TORCH_INTERNAL_ASSERT(
!pyRunFunction_.is_none(),
"Cannot run python UDF since pyRunFunction_ is None. Check if python RPC "
"handler is already cleaned up.");
return pyRunFunction_(pythonUdf);
}
SerializedPyObj PythonRpcHandler::serialize(const py::object& obj) {
PROFILE_GIL_SCOPED_ACQUIRE;
py::tuple t = pySerialize_(obj);
return SerializedPyObj(
t[0].cast<std::string>(), t[1].cast<std::vector<torch::Tensor>>());
}
py::object PythonRpcHandler::deserialize(const SerializedPyObj& serializedObj) {
PROFILE_GIL_SCOPED_ACQUIRE;
// NB: pyDeserialize_ can return an AttributeError if the deserialize() Python
// function fails. Functions consuming the result needs to handle such error
// properly.
return pyDeserialize_(
py::bytes(serializedObj.payload_), serializedObj.tensors_);
}
void PythonRpcHandler::handleException(const py::object& obj) {
PROFILE_GIL_SCOPED_ACQUIRE;
pyHandleException_(obj);
}
void PythonRpcHandler::handleExceptionGILHeld(const py::object& obj) {
TORCH_CHECK(PyGILState_Check(), "GIL should be held");
pyHandleException_(obj);
}
bool PythonRpcHandler::isRemoteException(const py::object& obj) {
PROFILE_GIL_SCOPED_ACQUIRE;
auto type = obj.get_type();
auto moduleName = type.attr("__module__").cast<std::string>();
auto qualName = type.attr("__qualname__").cast<std::string>();
return moduleName.compare(kInternalModule) == 0 &&
qualName.compare("RemoteException") == 0;
}
TypePtr PythonRpcHandler::parseTypeFromStr(const std::string& type_str) {
return typeParser_->parseType(type_str);
}
const PythonRpcHandler::RRefProxyFunctions& PythonRpcHandler::
getRRefProxyFunctions() const {
return rrefProxyFunctions_;
}
const PythonRpcHandler::RRefTypeFunctions& PythonRpcHandler::
getRRefTypeFunctions() const {
return rrefTypeFunctions_;
}
} // namespace rpc
} // namespace distributed
} // namespace torch
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