[3.14] gh-131038: Use text=True in subprocesses in test_perf_profiler (GH-137117) (#137124)

Author: miss-islington

Lib/test/test_perf_profiler.py

@@ -318,6 +318,7 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         env=env,
+        text=True,
     )
     if proc.returncode:
         print(proc.stderr, file=sys.stderr)
@@ -327,10 +328,10 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         jit_output_file = cwd + "/jit_output.dump"
         command = ("perf", "inject", "-j", "-i", output_file, "-o", jit_output_file)
         proc = subprocess.run(
-            command, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=env
+            command, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=env, text=True
         )
         if proc.returncode:
-            print(proc.stderr)
+            print(proc.stderr, file=sys.stderr)
             raise ValueError(f"Perf failed with return code {proc.returncode}")
         # Copy the jit_output_file to the output_file
         os.rename(jit_output_file, output_file)
@@ -342,10 +343,9 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         stderr=subprocess.PIPE,
         env=env,
         check=True,
+        text=True,
     )
-    return proc.stdout.decode("utf-8", "replace"), proc.stderr.decode(
-        "utf-8", "replace"
-    )
+    return proc.stdout, proc.stderr
 
 
 class TestPerfProfilerMixin: