feat: Add new histogram metric type (#374)

README.md

@@ -1656,12 +1656,12 @@ import triton_python_backend_utils as pb_utils
 class TritonPythonModel:
     def initialize(self, args):
       # Create a MetricFamily object to report the latency of the model
-      # execution. The 'kind' parameter must be either 'COUNTER' or
-      # 'GAUGE'.
+      # execution. The 'kind' parameter must be either 'COUNTER',
+      # 'GAUGE' or 'HISTOGRAM'.
       self.metric_family = pb_utils.MetricFamily(
           name="preprocess_latency_ns",
           description="Cumulative time spent pre-processing requests",
-          kind=pb_utils.MetricFamily.COUNTER # or pb_utils.MetricFamily.GAUGE
+          kind=pb_utils.MetricFamily.COUNTER
       )
 
       # Create a Metric object under the MetricFamily object. The 'labels'

src/ipc_message.h

@@ -1,4 +1,4 @@
-// Copyright 2021-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// Copyright 2021-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -63,6 +63,7 @@ typedef enum PYTHONSTUB_commandtype_enum {
   PYTHONSTUB_MetricRequestValue,
   PYTHONSTUB_MetricRequestIncrement,
   PYTHONSTUB_MetricRequestSet,
+  PYTHONSTUB_MetricRequestObserve,
   PYTHONSTUB_LoadModelRequest,
   PYTHONSTUB_UnloadModelRequest,
   PYTHONSTUB_ModelReadinessRequest,

src/metric.cc

@@ -1,4 +1,4 @@
-// Copyright 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// Copyright 2023-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -32,9 +32,12 @@
 
 namespace triton { namespace backend { namespace python {
 
-Metric::Metric(const std::string& labels, void* metric_family_address)
-    : labels_(labels), operation_value_(0), metric_address_(nullptr),
-      metric_family_address_(metric_family_address), is_cleared_(false)
+Metric::Metric(
+    const std::string& labels, std::optional<const std::vector<double>> buckets,
+    void* metric_family_address)
+    : labels_(labels), buckets_(buckets), operation_value_(0),
+      metric_address_(nullptr), metric_family_address_(metric_family_address),
+      is_cleared_(false)
 {
 #ifdef TRITON_PB_STUB
   SendCreateMetricRequest();
@@ -62,6 +65,20 @@ Metric::SaveToSharedMemory(std::unique_ptr<SharedMemoryManager>& shm_pool)
   custom_metric_shm_ptr_->metric_family_address = metric_family_address_;
   custom_metric_shm_ptr_->metric_address = metric_address_;
 
+  // Histogram specific case
+  if (buckets_.has_value()) {
+    auto buckets_size = buckets_.value().size() * sizeof(double);
+    std::unique_ptr<PbMemory> buckets_shm = PbMemory::Create(
+        shm_pool, TRITONSERVER_MemoryType::TRITONSERVER_MEMORY_CPU, 0,
+        buckets_size, reinterpret_cast<char*>(buckets_.value().data()),
+        false /* copy_gpu */);
+    custom_metric_shm_ptr_->buckets_shm_handle = buckets_shm->ShmHandle();
+    buckets_shm_ = std::move(buckets_shm);
+  } else {
+    custom_metric_shm_ptr_->buckets_shm_handle = 0;
+    buckets_shm_ = nullptr;
+  }
+
   // Save the references to shared memory.
   custom_metric_shm_ = std::move(custom_metric_shm);
   labels_shm_ = std::move(labels_shm);
@@ -80,17 +97,40 @@ Metric::LoadFromSharedMemory(
   std::unique_ptr<PbString> labels_shm = PbString::LoadFromSharedMemory(
       shm_pool, custom_metric_shm_ptr->labels_shm_handle);
 
-  return std::unique_ptr<Metric>(new Metric(custom_metric_shm, labels_shm));
+  std::unique_ptr<PbMemory> buckets_shm = nullptr;
+  if (custom_metric_shm_ptr->buckets_shm_handle != 0) {
+    buckets_shm = PbMemory::LoadFromSharedMemory(
+        shm_pool, custom_metric_shm_ptr->buckets_shm_handle,
+        false /* open_cuda_handle */);
+  }
+
+  return std::unique_ptr<Metric>(
+      new Metric(custom_metric_shm, labels_shm, buckets_shm));
 }
 
 Metric::Metric(
     AllocatedSharedMemory<MetricShm>& custom_metric_shm,
-    std::unique_ptr<PbString>& labels_shm)
+    std::unique_ptr<PbString>& labels_shm,
+    std::unique_ptr<PbMemory>& buckets_shm)
     : custom_metric_shm_(std::move(custom_metric_shm)),
-      labels_shm_(std::move(labels_shm))
+      labels_shm_(std::move(labels_shm)), buckets_shm_(std::move(buckets_shm))
 {
   custom_metric_shm_ptr_ = custom_metric_shm_.data_.get();
+
+  // FIXME: This constructor is called during each
+  // set/increment/observe/get_value call. It only needs the pointers.
   labels_ = labels_shm_->String();
+  if (buckets_shm_ != nullptr) {  // Histogram
+    size_t bucket_size = buckets_shm_->ByteSize() / sizeof(double);
+    std::vector<double> buckets;
+    buckets.reserve(bucket_size);
+    for (size_t i = 0; i < bucket_size; ++i) {
+      buckets.emplace_back(
+          reinterpret_cast<double*>(buckets_shm_->DataPtr())[i]);
+    }
+    buckets_ = std::move(buckets);
+  }
+
   operation_value_ = custom_metric_shm_ptr_->operation_value;
   metric_family_address_ = custom_metric_shm_ptr_->metric_family_address;
   metric_address_ = custom_metric_shm_ptr_->metric_address;
@@ -161,6 +201,24 @@ Metric::SendSetValueRequest(const double& value)
   }
 }
 
+void
+Metric::SendObserveRequest(const double& value)
+{
+  try {
+    CheckIfCleared();
+    std::unique_ptr<Stub>& stub = Stub::GetOrCreateInstance();
+    operation_value_ = value;
+    SaveToSharedMemory(stub->ShmPool());
+    AllocatedSharedMemory<CustomMetricsMessage> custom_metrics_shm;
+    stub->SendMessage<CustomMetricsMessage>(
+        custom_metrics_shm, PYTHONSTUB_MetricRequestObserve, shm_handle_);
+  }
+  catch (const PythonBackendException& pb_exception) {
+    throw PythonBackendException(
+        "Failed to observe metric value: " + std::string(pb_exception.what()));
+  }
+}
+
 double
 Metric::SendGetValueRequest()
 {
@@ -222,14 +280,35 @@ Metric::InitializeTritonMetric()
 {
   std::vector<const TRITONSERVER_Parameter*> labels_params;
   ParseLabels(labels_params, labels_);
+  TRITONSERVER_MetricKind kind;
+  THROW_IF_TRITON_ERROR(TRITONSERVER_GetMetricFamilyKind(
+      reinterpret_cast<TRITONSERVER_MetricFamily*>(metric_family_address_),
+      &kind));
+  TRITONSERVER_MetricArgs* args = nullptr;
+  switch (kind) {
+    case TRITONSERVER_METRIC_KIND_COUNTER:
+    case TRITONSERVER_METRIC_KIND_GAUGE:
+      break;
+    case TRITONSERVER_METRIC_KIND_HISTOGRAM: {
+      const std::vector<double>& buckets = buckets_.value();
+      THROW_IF_TRITON_ERROR(TRITONSERVER_MetricArgsNew(&args));
+      THROW_IF_TRITON_ERROR(TRITONSERVER_MetricArgsSetHistogram(
+          args, buckets.data(), buckets.size()));
+      break;
+    }
+    default:
+      break;
+  }
+
   TRITONSERVER_Metric* triton_metric = nullptr;
-  THROW_IF_TRITON_ERROR(TRITONSERVER_MetricNew(
+  THROW_IF_TRITON_ERROR(TRITONSERVER_MetricNewWithArgs(
       &triton_metric,
       reinterpret_cast<TRITONSERVER_MetricFamily*>(metric_family_address_),
-      labels_params.data(), labels_params.size()));
+      labels_params.data(), labels_params.size(), args));
   for (const auto label : labels_params) {
     TRITONSERVER_ParameterDelete(const_cast<TRITONSERVER_Parameter*>(label));
   }
+  THROW_IF_TRITON_ERROR(TRITONSERVER_MetricArgsDelete(args));
   return reinterpret_cast<void*>(triton_metric);
 }
 
@@ -262,6 +341,8 @@ Metric::HandleMetricOperation(
     Increment(operation_value_);
   } else if (command_type == PYTHONSTUB_MetricRequestSet) {
     SetValue(operation_value_);
+  } else if (command_type == PYTHONSTUB_MetricRequestObserve) {
+    Observe(operation_value_);
   } else {
     throw PythonBackendException("Unknown metric operation");
   }
@@ -281,6 +362,13 @@ Metric::SetValue(const double& value)
   THROW_IF_TRITON_ERROR(TRITONSERVER_MetricSet(triton_metric, value));
 }
 
+void
+Metric::Observe(const double& value)
+{
+  auto triton_metric = reinterpret_cast<TRITONSERVER_Metric*>(metric_address_);
+  THROW_IF_TRITON_ERROR(TRITONSERVER_MetricObserve(triton_metric, value));
+}
+
 double
 Metric::GetValue()
 {

src/metric.h

@@ -1,4 +1,4 @@
-// Copyright 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// Copyright 2023-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -26,9 +26,11 @@
 
 #pragma once
 
+#include <optional>
 #include <string>
 
 #include "ipc_message.h"
+#include "pb_memory.h"
 #include "pb_string.h"
 #include "pb_utils.h"
 
@@ -47,6 +49,8 @@ namespace triton { namespace backend { namespace python {
 struct MetricShm {
   // The shared memory handle of the labels in PbString format.
   bi::managed_external_buffer::handle_t labels_shm_handle;
+  // The shared memory handle of the buckets in PbMemory format.
+  bi::managed_external_buffer::handle_t buckets_shm_handle;
   // The value used for incrementing or setting the metric.
   double operation_value;
   // The address of the TRITONSERVER_Metric object.
@@ -58,7 +62,10 @@ struct MetricShm {
 
 class Metric {
  public:
-  Metric(const std::string& labels, void* metric_family_address);
+  Metric(
+      const std::string& labels,
+      std::optional<const std::vector<double>> buckets,
+      void* metric_family_address);
 
   ~Metric();
 
@@ -97,6 +104,10 @@ class Metric {
   /// \param value The value to set the metric to.
   void SendSetValueRequest(const double& value);
 
+  /// Send the request to the parent process to observe the value to the metric.
+  /// \param value The value to set the metric to.
+  void SendObserveRequest(const double& value);
+
   /// Send the request to the parent process to get the value of the metric.
   /// \return Returns the value of the metric.
   double SendGetValueRequest();
@@ -132,6 +143,10 @@ class Metric {
   /// \param value The value to set the metric to.
   void SetValue(const double& value);
 
+  /// Use Triton C API to sample the observation to the metric.
+  /// \param value The value to sample observation to the metric.
+  void Observe(const double& value);
+
   /// Use Triton C API to get the value of the metric.
   double GetValue();
 
@@ -146,10 +161,14 @@ class Metric {
   // The private constructor for creating a Metric object from shared memory.
   Metric(
       AllocatedSharedMemory<MetricShm>& custom_metric_shm,
-      std::unique_ptr<PbString>& labels_shm);
+      std::unique_ptr<PbString>& labels_shm,
+      std::unique_ptr<PbMemory>& buckets);
 
   // The labels of the metric, which is the identifier of the metric.
   std::string labels_;
+  // Monotonically increasing values representing bucket boundaries for creating
+  // histogram metric.
+  std::optional<std::vector<double>> buckets_;
   // The value used for incrementing or setting the metric.
   double operation_value_;
   // The address of the TRITONSERVER_Metric object.
@@ -168,6 +187,7 @@ class Metric {
   MetricShm* custom_metric_shm_ptr_;
   bi::managed_external_buffer::handle_t shm_handle_;
   std::unique_ptr<PbString> labels_shm_;
+  std::unique_ptr<PbMemory> buckets_shm_;
 };
 
 }}};  // namespace triton::backend::python

src/metric_family.cc

@@ -1,4 +1,4 @@
-// Copyright 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// Copyright 2023-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -166,19 +166,39 @@ MetricFamily::SendCreateMetricFamilyRequest()
 }
 
 std::shared_ptr<Metric>
-MetricFamily::CreateMetric(const py::object& labels)
+MetricFamily::CreateMetric(const py::object& labels, const py::object& buckets)
 {
   if (!labels.is_none()) {
     if (!py::isinstance<py::dict>(labels)) {
       throw PythonBackendException(
-          "Failed to create metric. Labels must be a "
-          "dictionary.");
+          "Failed to create metric. Labels must be a dictionary.");
     }
   }
 
   py::module json = py::module_::import("json");
   std::string labels_str = std::string(py::str(json.attr("dumps")(labels)));
-  auto metric = std::make_shared<Metric>(labels_str, metric_family_address_);
+
+  std::optional<std::vector<double>> buckets_vec;
+  if (!buckets.is_none()) {
+    if (!py::isinstance<py::list>(buckets)) {
+      throw PythonBackendException(
+          "Failed to create metric. Buckets must be a list.");
+    }
+    if (kind_ == kCounter || kind_ == kGauge) {
+      throw PythonBackendException(
+          "Failed to create metric. Unexpected buckets found.");
+    }
+    buckets_vec = buckets.cast<std::vector<double>>();
+  } else {
+    if (kind_ == kHistogram) {
+      throw PythonBackendException(
+          "Failed to create metric. Missing required buckets.");
+    }
+    buckets_vec = std::nullopt;
+  }
+
+  auto metric =
+      std::make_shared<Metric>(labels_str, buckets_vec, metric_family_address_);
   {
     std::lock_guard<std::mutex> lock(metric_map_mu_);
     metric_map_.insert({metric->MetricAddress(), metric});
@@ -205,6 +225,8 @@ MetricFamily::ToTritonServerMetricKind(const MetricKind& kind)
       return TRITONSERVER_METRIC_KIND_COUNTER;
     case kGauge:
       return TRITONSERVER_METRIC_KIND_GAUGE;
+    case kHistogram:
+      return TRITONSERVER_METRIC_KIND_HISTOGRAM;
     default:
       throw PythonBackendException("Unknown metric kind");
   }

src/metric_family.h

@@ -1,4 +1,4 @@
-// Copyright 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// Copyright 2023-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
@@ -97,8 +97,11 @@ class MetricFamily {
 
   /// Create a metric from the metric family and store it in the metric map.
   /// \param labels The labels of the metric.
+  /// \param buckets Monotonically increasing values representing bucket
+  /// boundaries for creating histogram metric.
   /// \return Returns the shared pointer to the created metric.
-  std::shared_ptr<Metric> CreateMetric(const py::object& labels);
+  std::shared_ptr<Metric> CreateMetric(
+      const py::object& labels, const py::object& buckets);
 #else
   /// Initialize the TRITONSERVER_MetricFamily object.
   /// \return Returns the address of the TRITONSERVER_MetricFamily object.
@@ -128,8 +131,8 @@ class MetricFamily {
   std::string name_;
   // The description of the metric family.
   std::string description_;
-  // The metric kind of the metric family. Currently only supports GAUGE and
-  // COUNTER.
+  // The metric kind of the metric family. Currently only supports GAUGE,
+  // COUNTER and HISTOGRAM.
   MetricKind kind_;
   // The address of the TRITONSERVER_MetricFamily object.
   void* metric_family_address_;