pytorch/torch/csrc/distributed/rpc/utils.cpp
Hongyi Jia 3411ec6e32 [TensorPipe/RPC] Serialize and deserialize message (#36197)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36197

Create APIs to convert between rpc::message and tensorpipe::message
1. tensorpipeSerialize() - converts rpc::message to tensorpipe::message without memory copy (tensors).
2. tensorpipeAllocateMessage - allocates rpc::message based on received tensorpipe descriptor to prepare memory-copy-free receiving.

Test Plan: buck test caffe2/test/cpp/rpc:test_tensorpipe_serialization

Reviewed By: lw

Differential Revision: D20084125

fbshipit-source-id: ffbc310f93443e50261aed752be0fe176610dd2a
2020-05-05 05:45:57 -07:00

465 lines
15 KiB
C++

#include <torch/csrc/distributed/rpc/utils.h>
#include <torch/csrc/distributed/autograd/rpc_messages/cleanup_autograd_context_req.h>
#include <torch/csrc/distributed/autograd/rpc_messages/cleanup_autograd_context_resp.h>
#include <torch/csrc/distributed/autograd/rpc_messages/propagate_gradients_req.h>
#include <torch/csrc/distributed/autograd/rpc_messages/propagate_gradients_resp.h>
#include <torch/csrc/distributed/autograd/rpc_messages/rpc_with_autograd.h>
#include <torch/csrc/distributed/autograd/utils.h>
#include <torch/csrc/distributed/rpc/python_call.h>
#include <torch/csrc/distributed/rpc/python_remote_call.h>
#include <torch/csrc/distributed/rpc/python_resp.h>
#include <torch/csrc/distributed/rpc/rref_proto.h>
#include <torch/csrc/distributed/rpc/script_call.h>
#include <torch/csrc/distributed/rpc/script_remote_call.h>
#include <torch/csrc/distributed/rpc/script_resp.h>
#include <torch/csrc/jit/serialization/pickler.h>
#include <torch/csrc/jit/serialization/unpickler.h>
namespace torch {
namespace distributed {
namespace rpc {
std::unique_ptr<RpcCommandBase> deserializeRequest(const Message& request) {
switch (request.type()) {
case MessageType::SCRIPT_CALL: {
return ScriptCall::fromMessage(request);
}
case MessageType::PYTHON_CALL: {
return PythonCall::fromMessage(request);
}
case MessageType::SCRIPT_REMOTE_CALL: {
return ScriptRemoteCall::fromMessage(request);
}
case MessageType::PYTHON_REMOTE_CALL: {
return PythonRemoteCall::fromMessage(request);
}
case MessageType::SCRIPT_RREF_FETCH_CALL: {
return ScriptRRefFetchCall::fromMessage(request);
}
case MessageType::PYTHON_RREF_FETCH_CALL: {
return PythonRRefFetchCall::fromMessage(request);
}
case MessageType::RREF_USER_DELETE: {
return RRefUserDelete::fromMessage(request);
}
case MessageType::RREF_CHILD_ACCEPT: {
return RRefChildAccept::fromMessage(request);
}
case MessageType::RREF_FORK_REQUEST: {
return RRefForkRequest::fromMessage(request);
}
case MessageType::FORWARD_AUTOGRAD_REQ: {
return autograd::RpcWithAutograd::fromMessage(request);
}
case MessageType::BACKWARD_AUTOGRAD_REQ: {
return autograd::PropagateGradientsReq::fromMessage(request);
}
case MessageType::CLEANUP_AUTOGRAD_CONTEXT_REQ: {
return autograd::CleanupAutogradContextReq::fromMessage(request);
}
default: {
TORCH_INTERNAL_ASSERT(
false, "Request type ", request.type(), " not supported.");
}
}
}
std::unique_ptr<RpcCommandBase> deserializeResponse(
const Message& response,
MessageType& wrappedMsgType) {
switch (response.type()) {
case MessageType::SCRIPT_RET: {
return ScriptResp::fromMessage(response);
}
case MessageType::PYTHON_RET: {
return PythonResp::fromMessage(response);
}
case MessageType::REMOTE_RET: {
return RemoteRet::fromMessage(response);
}
case MessageType::SCRIPT_RREF_FETCH_RET: {
return ScriptRRefFetchRet::fromMessage(response);
}
case MessageType::PYTHON_RREF_FETCH_RET: {
return PythonRRefFetchRet::fromMessage(response);
}
case MessageType::RREF_ACK: {
return RRefAck::fromMessage(response);
}
case MessageType::FORWARD_AUTOGRAD_RESP: {
std::unique_ptr<RpcCommandBase> rpcPtr =
autograd::RpcWithAutograd::fromMessage(response);
RpcCommandBase& rpc = *rpcPtr;
auto& rpcWithAutograd = static_cast<autograd::RpcWithAutograd&>(rpc);
// Attach 'recv' autograd function.
addRecvRpcBackward(
rpcWithAutograd.autogradMetadata(),
rpcWithAutograd.tensors(),
rpcWithAutograd.fromWorkerId());
wrappedMsgType = rpcWithAutograd.wrappedMessageType();
return std::move(rpcWithAutograd).moveWrappedRpc();
}
case MessageType::BACKWARD_AUTOGRAD_RESP: {
return autograd::PropagateGradientsResp::fromMessage(response);
}
case MessageType::CLEANUP_AUTOGRAD_CONTEXT_RESP: {
return autograd::CleanupAutogradContextResp::fromMessage(response);
}
default: {
TORCH_INTERNAL_ASSERT(
false, "Response type ", response.type(), " not supported.");
}
}
}
IValue deserializeResptoIValueInternal(
RpcCommandBase& rpc,
MessageType messageType) {
switch (messageType) {
case MessageType::SCRIPT_RET: {
auto& ret = static_cast<ScriptResp&>(rpc);
return ret.value();
}
default: {
TORCH_INTERNAL_ASSERT(
false,
"Response type ",
messageType,
" is not supported to be deserialized to IValue.");
}
}
}
IValue deserializeRespToIValue(const Message& message) {
MessageType msgType = message.type();
auto response = deserializeResponse(message, msgType);
return deserializeResptoIValueInternal(*response, msgType);
}
namespace {
// Helper for wireDeserialize() below.
//
// The format we use below looks like:
// section_name_1 size_1\n
// section_name_2 size_2\n
// ..
// \n
// [sections in order]
//
// Sections themselves include:
// - "payload" - the payload bits
// - "meta" - metadata for the unpickler
// - "0" ... - tensor sections for the unpickler
//
// Note that per the header comments, the format is subject to change,
// and is best used for rpcs, rather than persistent disk storage.
std::unordered_map<std::string, std::pair<const char*, size_t>>
parseWireSections(const void* data, size_t data_size) {
const char* ptr = static_cast<const char*>(data);
const char* endp = ptr + data_size;
std::vector<std::pair<std::string, size_t>> headerEnts;
bool ok = false;
while (ptr != endp) {
if (*ptr == '\n') {
ok = true; // The only "correct" exit point.
++ptr;
break;
}
// Parse name
const char* namePtr = ptr;
while (ptr != endp && *ptr != ' ') {
ptr++;
}
if (ptr == endp) {
break;
}
std::string name(namePtr, ptr - namePtr);
if (++ptr == endp) {
break; // past the ' '
}
// Parse size
const char* sizePtr = ptr;
while (ptr != endp && *ptr != '\n') {
ptr++;
}
if (ptr == endp) {
break;
}
size_t sz = c10::stoll(std::string(sizePtr, ptr - sizePtr));
headerEnts.emplace_back(std::make_pair(name, sz));
++ptr; // past the '\n'
}
if (!ok) {
throw std::runtime_error("failed parse");
}
std::unordered_map<std::string, std::pair<const char*, size_t>> out;
for (const auto& headerEnt : headerEnts) {
out[headerEnt.first] = {ptr, headerEnt.second};
ptr += headerEnt.second;
}
if (ptr != endp) {
throw std::runtime_error("failed bounds");
}
return out;
}
static const char* kMeta = "meta";
static const char* kPayload = "payload";
}; // namespace
c10::List<at::Tensor> cloneSparseTensors(
const std::vector<at::Tensor>& tensors) {
// Sanity-check: If the majority of bits don't need to go over the wire,
// force a clone(). Some Tensors are effectively small views, only using
// ~1% of the underlying Storage.
auto worthRecopying = [](const at::Tensor& t) -> bool {
if (!t.has_storage()) {
return false; // avoid throwing below.
}
auto storageSize = t.storage().elementSize() * t.storage().numel();
auto usefulSize = t.element_size() * t.numel();
constexpr size_t kMinMultiple = 2;
constexpr size_t kMinRecopyBytes = 8 * 1024;
return storageSize >= kMinRecopyBytes &&
storageSize >= usefulSize * kMinMultiple;
};
c10::List<at::Tensor> pTensors;
pTensors.reserve(tensors.size());
for (const auto& t : tensors) {
pTensors.push_back(worthRecopying(t) ? t.clone() : t);
}
return pTensors;
}
std::string wireSerialize(
const std::vector<char>& payload,
const std::vector<at::Tensor>& tensors) {
for (const auto& tensor : tensors) {
TORCH_CHECK(
tensor.device().is_cpu(),
"ProcessGroup RPC backend only supports",
" CPU tensors, please move your tensors to CPU before sending ",
"them over RPC. Found tensor on device: ",
tensor.device());
}
struct Ent {
std::string name;
const char* data;
size_t size;
};
std::vector<Ent> entries;
std::string metaEntry;
std::vector<jit::WriteableTensorData> tensorData;
if (!payload.empty()) {
entries.push_back({kPayload, payload.data(), payload.size()});
}
if (!tensors.empty()) {
torch::jit::Pickler pickler([&](const void* buf, size_t sz) -> size_t {
metaEntry.append(static_cast<const char*>(buf), sz);
return sz;
});
pickler.protocol();
pickler.pushIValue(cloneSparseTensors(tensors));
pickler.stop();
// tensorData is in function scope so that the data() pointers stay valid.
tensorData = pickler.tensorData();
entries.push_back({kMeta, metaEntry.data(), metaEntry.size()});
for (size_t i = 0; i < tensorData.size(); i++) {
entries.push_back({c10::to_string(i),
tensorData[i].data(),
tensorData[i].sizeInBytes()});
}
}
std::string header;
size_t tot = 0;
for (const auto& e : entries) {
tot += e.size;
header.append(e.name)
.append(" ")
.append(c10::to_string(e.size))
.append("\n");
}
header.push_back('\n');
std::string out;
out.reserve(header.size() + tot);
out.append(header);
for (const auto& e : entries) {
out.append(e.data, e.size);
}
return out;
}
std::pair<std::vector<char>, std::vector<at::Tensor>> wireDeserialize(
const void* data,
size_t data_size) {
auto sections = parseWireSections(data, data_size);
std::vector<char> payload;
auto payloadIt = sections.find(kPayload);
if (payloadIt != sections.end() && payloadIt->second.second != 0) {
payload.assign(
payloadIt->second.first,
payloadIt->second.first + payloadIt->second.second);
}
std::vector<at::Tensor> tensors;
auto metaIt = sections.find(kMeta);
if (metaIt != sections.end()) {
const auto& metaData = metaIt->second;
size_t metaDataPos = 0;
auto metaDataReadFunc = [&](char* buf, size_t n) -> size_t {
if (metaDataPos >= metaData.second || n == 0) {
return 0;
}
size_t toCopy = std::min(metaDataPos + n, metaData.second) - metaDataPos;
memcpy(buf, metaData.first + metaDataPos, toCopy);
metaDataPos += toCopy;
return toCopy;
};
auto sectionReadFunc = [&](const std::string& ename) -> at::DataPtr {
auto it = sections.find(ename);
if (it == sections.end()) {
throw std::runtime_error("Couldn't find entity " + ename);
}
const auto& idat = it->second;
auto dptr = at::getCPUAllocator()->allocate(idat.second);
if (idat.second != 0) {
memcpy(dptr.get(), idat.first, idat.second);
}
return dptr;
};
// No need to pass typeResolver here, as it always processes string and
// tensors only
torch::jit::Unpickler unpickler(
metaDataReadFunc, nullptr, nullptr, sectionReadFunc, {});
auto ival = unpickler.parse_ivalue();
for (auto&& t : ival.toTensorList()) {
tensors.emplace_back(std::move(t));
}
}
return {std::move(payload), std::move(tensors)};
}
TensorPipeEntry tensorpipeSerialize(const Message& rpcMessage) {
tensorpipe::Message tpMessage;
std::vector<torch::Tensor> reservedTensors;
std::vector<std::vector<uint8_t>> copiedTensors;
const std::vector<char>& payload = rpcMessage.payload();
c10::List<at::Tensor> tensors = cloneSparseTensors(rpcMessage.tensors());
// Payload
tpMessage.data = (uint8_t*)(payload.data());
tpMessage.length = payload.size();
// Metadata - encode rpc message type and message id into
// 8 bytes respectively
tpMessage.metadata.resize(2 * sizeof(int64_t));
int64_t mType = static_cast<int>(rpcMessage.type());
int64_t mId = rpcMessage.id();
memcpy((void*)tpMessage.metadata.data(), &mType, sizeof(int64_t));
memcpy(
(void*)(tpMessage.metadata.data() + sizeof(int64_t)),
&mId,
sizeof(int64_t));
// Tensors
tpMessage.tensors.reserve(tensors.size());
for (at::Tensor tensor : tensors) {
// Keep original user tensors and cloned sparse tensors
reservedTensors.push_back(tensor);
tensorpipe::Message::Tensor tpTensor;
torch::jit::Pickler pickler([&](const void* buf, size_t sz) -> size_t {
tpTensor.metadata.append(static_cast<const char*>(buf), sz);
return sz;
});
pickler.protocol();
pickler.pushIValue(tensor);
pickler.stop();
const auto& tensorDataVec = pickler.tensorData();
TORCH_INTERNAL_ASSERT(
tensorDataVec.size() == 1, "There should be single pickled tensor");
const auto& tensorData = tensorDataVec.front();
// Enforce memory copy if tensor is created from torch::from_blob, means
// that the tensor doesn't own the memory.
if (!tensorData.storageHasDeleter()) {
std::vector<uint8_t> storageData(tensorData.sizeInBytes());
memcpy(storageData.data(), tensorData.data(), storageData.size());
tpTensor.data = storageData.data();
copiedTensors.push_back(std::move(storageData));
} else {
tpTensor.data = (uint8_t*)(tensorData.data());
}
tpTensor.length = tensorData.sizeInBytes();
tpMessage.tensors.push_back(std::move(tpTensor));
}
return TensorPipeEntry{std::move(tpMessage),
std::move(reservedTensors),
std::move(copiedTensors)};
}
Message tensorpipeAllocateMessage(const tensorpipe::Message& tpMessage) {
// Payload, message type and message id
std::vector<char> payload(tpMessage.length);
TORCH_INTERNAL_ASSERT(
tpMessage.metadata.size() == 2 * sizeof(int64_t),
"message metadata must be ",
2 * sizeof(int64_t),
" bytes, whereas it is ",
tpMessage.metadata.size(),
" bytes");
int64_t mtypei, mId;
memcpy(&mtypei, tpMessage.metadata.data(), sizeof(int64_t));
memcpy(&mId, tpMessage.metadata.data() + sizeof(int64_t), sizeof(int64_t));
MessageType mType = static_cast<MessageType>(mtypei);
// Tensors
std::vector<torch::Tensor> tensors;
tensors.reserve(tpMessage.tensors.size());
for (const tensorpipe::Message::Tensor& tpTensor : tpMessage.tensors) {
const std::string& metadata = tpTensor.metadata;
size_t metadataPos = 0;
auto metaDataReadFunc = [&](char* buf, size_t n) -> size_t {
if (metadataPos >= metadata.size() || n == 0) {
return 0;
}
size_t toCopy = std::min(n, metadata.size() - metadataPos);
memcpy(buf, metadata.data() + metadataPos, toCopy);
metadataPos += toCopy;
return toCopy;
};
auto sectionReadFunc = [&](const std::string& ename) -> at::DataPtr {
TORCH_INTERNAL_ASSERT(ename == "0", "single tensor ename must be \"0\"");
// TODO: CUDA memory allocation
return at::getCPUAllocator()->allocate(tpTensor.length);
};
torch::jit::Unpickler unpickler(
metaDataReadFunc, nullptr, nullptr, sectionReadFunc, {});
auto ival = unpickler.parse_ivalue();
auto&& t = ival.toTensor();
tensors.emplace_back(std::move(t));
}
return Message(std::move(payload), std::move(tensors), mType, mId);
}
} // namespace rpc
} // namespace distributed
} // namespace torch