Re-apply "Merge pull request #4401 from DataDog/ivoanjo/prof-11394-heap-profiler-preview"

This reverts commit 32ded2e, thus
re-applying the changes from #4401.

Author: ivoanjo

lib/datadog/core/configuration/settings.rb

@@ -313,7 +313,7 @@ def initialize(*_)
 
             # Can be used to enable/disable the collection of heap profiles.
             #
-            # This feature is alpha and disabled by default
+            # This feature is in preview and disabled by default. Requires Ruby 3.1+.
             #
             # @warn To enable heap profiling you are required to also enable allocation profiling.
             #
@@ -326,12 +326,12 @@ def initialize(*_)
 
             # Can be used to enable/disable the collection of heap size profiles.
             #
-            # This feature is alpha and enabled by default when heap profiling is enabled.
+            # This feature is in preview and by default is enabled whenever heap profiling is enabled.
             #
-            # @warn To enable heap size profiling you are required to also enable allocation and heap profiling.
+            # @warn Heap size profiling depends on allocation and heap profiling, so they must be enabled as well.
             #
-            # @default `DD_PROFILING_EXPERIMENTAL_HEAP_SIZE_ENABLED` environment variable as a boolean, otherwise
-            # whatever the value of DD_PROFILING_EXPERIMENTAL_HEAP_ENABLED is.
+            # @default `DD_PROFILING_EXPERIMENTAL_HEAP_SIZE_ENABLED` environment variable as a boolean, otherwise it
+            # follows the value of `experimental_heap_enabled`.
             option :experimental_heap_size_enabled do |o|
               o.type :bool
               o.env 'DD_PROFILING_EXPERIMENTAL_HEAP_SIZE_ENABLED'

lib/datadog/profiling/component.rb

@@ -221,13 +221,14 @@ def self.build_profiler_component(settings:, agent_settings:, optional_tracer:,
         end
 
         unless allocation_profiling_enabled
-          raise ArgumentError, "Heap profiling requires allocation profiling to be enabled"
+          logger.warn(
+            "Heap profiling was requested but allocation profiling is not enabled. " \
+            "Heap profiling has been disabled."
+          )
+          return false
         end
 
-        logger.warn(
-          "Enabled experimental heap profiling: heap_sample_rate=#{heap_sample_rate}. This is experimental, not " \
-          "recommended, and will increase overhead!"
-        )
+        logger.debug("Enabled heap profiling: heap_sample_rate=#{heap_sample_rate}")
 
         true
       end
@@ -237,10 +238,6 @@ def self.build_profiler_component(settings:, agent_settings:, optional_tracer:,
 
         return false unless heap_profiling_enabled && heap_size_profiling_enabled
 
-        logger.warn(
-          "Enabled experimental heap size profiling. This is experimental, not recommended, and will increase overhead!"
-        )
-
         true
       end
 

spec/datadog/profiling/component_spec.rb

@@ -331,8 +331,14 @@
               settings.profiling.allocation_enabled = false
             end
 
-            it "raises an ArgumentError during component initialization" do
-              expect { build_profiler_component }.to raise_error(ArgumentError, /requires allocation profiling/)
+            it "initializes StackRecorder without heap sampling support and warns" do
+              expect(Datadog::Profiling::StackRecorder).to receive(:new)
+                .with(hash_including(heap_samples_enabled: false, heap_size_enabled: false))
+                .and_call_original
+
+              expect(logger).to receive(:warn).with(/allocation profiling is not enabled/)
+
+              build_profiler_component
             end
           end
 
@@ -350,8 +356,7 @@
 
               expect(logger).to receive(:info).with(/Ractors.+stopping/)
               expect(logger).to receive(:debug).with(/Enabled allocation profiling/)
-              expect(logger).to receive(:warn).with(/experimental heap profiling/)
-              expect(logger).to receive(:warn).with(/experimental heap size profiling/)
+              expect(logger).to receive(:debug).with(/Enabled heap profiling/)
 
               build_profiler_component
             end
@@ -368,8 +373,7 @@
 
                 expect(logger).to receive(:info).with(/Ractors.+stopping/)
                 expect(logger).to receive(:debug).with(/Enabled allocation profiling/)
-                expect(logger).to receive(:warn).with(/experimental heap profiling/)
-                expect(logger).not_to receive(:warn).with(/experimental heap size profiling/)
+                expect(logger).to receive(:debug).with(/Enabled heap profiling/)
 
                 build_profiler_component
               end