Close popen pipe after used (#47053)

python/paddle/fluid/core.py

@@ -73,7 +73,9 @@ def avx_supported():
     has_avx = False
     if sysstr == 'linux':
         try:
-            has_avx = os.popen('cat /proc/cpuinfo | grep -i avx').read() != ''
+            pipe = os.popen('cat /proc/cpuinfo | grep -i avx')
+            has_avx = pipe.read() != ''
+            pipe.close()
         except Exception as e:
             sys.stderr.write(
                 'Can not get the AVX flag from /proc/cpuinfo.\n'
@@ -82,10 +84,9 @@ def avx_supported():
         return has_avx
     elif sysstr == 'darwin':
         try:
-            has_avx = (
-                os.popen('sysctl machdep.cpu.features | grep -i avx').read()
-                != ''
-            )
+            pipe = os.popen('sysctl machdep.cpu.features | grep -i avx')
+            has_avx = pipe.read() != ''
+            pipe.close()
         except Exception as e:
             sys.stderr.write(
                 'Can not get the AVX flag from machdep.cpu.features.\n'