feat(simulation): add Python allocator opt-out

Add an experimental flag that unsets PYTHONMALLOC for simulation runs, allowing integrations to validate workloads without the forced malloc allocator before it becomes the default behavior.

Author: not-matthias

src/cli/exec/mod.rs

@@ -94,6 +94,10 @@ fn build_orchestrator_config(
         exclude_allocations: args.shared.exclude_allocations,
         simulation_track_subprocess: args.shared.simulation_track_subprocess,
         memory_track_physical: args.shared.experimental.experimental_memory_track_physical,
+        disable_pythonmalloc_override: args
+            .shared
+            .experimental
+            .experimental_disable_pythonmalloc_override,
     })
 }
 

src/cli/experimental.rs

@@ -27,6 +27,15 @@ pub struct ExperimentalArgs {
     )]
     pub experimental_memory_track_physical: bool,
 
+    /// Do not set PYTHONMALLOC for simulation runs.
+    #[arg(
+        long,
+        default_value_t = false,
+        help_heading = "Experimental",
+        env = "CODSPEED_EXPERIMENTAL_DISABLE_PYTHONMALLOC_OVERRIDE"
+    )]
+    pub experimental_disable_pythonmalloc_override: bool,
+
     /// Deprecated: cycle estimation is enabled by default and this flag has no effect.
     #[arg(long, hide = true, env = "CODSPEED_EXPERIMENTAL_CYCLE_ESTIMATION")]
     pub experimental_cycle_estimation: bool,
@@ -46,6 +55,9 @@ impl ExperimentalArgs {
         if self.experimental_memory_track_physical {
             flags.push("--experimental-memory-track-physical");
         }
+        if self.experimental_disable_pythonmalloc_override {
+            flags.push("--experimental-disable-pythonmalloc-override");
+        }
         flags
     }
 

src/cli/run/mod.rs

@@ -84,6 +84,7 @@ impl RunArgs {
                     experimental_cycle_estimation: false,
                     experimental_exclude_allocations: false,
                     experimental_memory_track_physical: false,
+                    experimental_disable_pythonmalloc_override: false,
                 },
             },
             instruments: vec![],
@@ -137,6 +138,10 @@ fn build_orchestrator_config(
         exclude_allocations: args.shared.exclude_allocations,
         simulation_track_subprocess: args.shared.simulation_track_subprocess,
         memory_track_physical: args.shared.experimental.experimental_memory_track_physical,
+        disable_pythonmalloc_override: args
+            .shared
+            .experimental
+            .experimental_disable_pythonmalloc_override,
     })
 }
 

src/executor/config.rs

@@ -100,6 +100,8 @@ pub struct OrchestratorConfig {
     pub simulation_track_subprocess: bool,
     /// Enable physical (resident) memory tracking in memory mode.
     pub memory_track_physical: bool,
+    /// Do not set PYTHONMALLOC for simulation runs.
+    pub disable_pythonmalloc_override: bool,
 }
 
 /// Per-execution configuration passed to executors.
@@ -145,6 +147,8 @@ pub struct ExecutorConfig {
     /// Only read by the memory executor, which is Linux-only.
     #[cfg_attr(not(target_os = "linux"), allow(dead_code))]
     pub memory_track_physical: bool,
+    /// Do not set PYTHONMALLOC for simulation runs.
+    pub disable_pythonmalloc_override: bool,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -218,6 +222,7 @@ impl OrchestratorConfig {
             exclude_allocations: self.exclude_allocations,
             simulation_track_subprocess: self.simulation_track_subprocess,
             memory_track_physical: self.memory_track_physical,
+            disable_pythonmalloc_override: self.disable_pythonmalloc_override,
         }
     }
 }
@@ -254,6 +259,7 @@ impl OrchestratorConfig {
             exclude_allocations: false,
             simulation_track_subprocess: false,
             memory_track_physical: false,
+            disable_pythonmalloc_override: false,
         }
     }
 }

src/executor/valgrind/measure.rs

@@ -140,7 +140,9 @@ pub async fn measure(
 
     // Free-threaded Python (GIL disabled) does not support PYTHONMALLOC=malloc
     // and refuses to start with it set.
-    if !is_free_threaded_python(config.working_directory.as_deref().map(Path::new)) {
+    if !config.disable_pythonmalloc_override
+        && !is_free_threaded_python(config.working_directory.as_deref().map(Path::new))
+    {
         cmd.env("PYTHONMALLOC", "malloc");
     }