From 956c89a049255cf0a0ac52e813c45171329275d7 Mon Sep 17 00:00:00 2001
From: Martin Bauer <martin.bauer@fau.de>
Date: Fri, 20 Apr 2018 10:09:07 +0200
Subject: [PATCH] Bug fix for shared library cache -> switched to atomic
filesystem write
- when running multiple pystencils instances, sometimes errors happened
because one process might have partially written a cached file, which
is already read before writing was finished
-> switched to "atomic write" (only on linux yet) that uses os.rename
which is guaranteed to be atomic
---
cpu/cpujit.py | 41 +++++++++++++++++++++--------------------
utils.py | 32 ++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+), 20 deletions(-)
diff --git a/cpu/cpujit.py b/cpu/cpujit.py
index 7f32f2b5e..b793302e2 100644
--- a/cpu/cpujit.py
+++ b/cpu/cpujit.py
@@ -76,7 +76,7 @@ from collections import OrderedDict
from pystencils.transformations import symbol_name_to_variable_name
from pystencils.data_types import to_ctypes, get_base_type, StructType
from pystencils.field import FieldType
-from pystencils.utils import recursive_dict_update
+from pystencils.utils import recursive_dict_update, file_handle_for_atomic_write, atomic_file_write
def make_python_function(kernel_function_node, argument_dict={}):
@@ -263,19 +263,18 @@ def compile_object_cache_to_shared_library():
atexit.register(compile_object_cache_to_shared_library)
-def generate_code(ast, restrict_qualifier, function_prefix, target_file):
+def generate_code(ast, restrict_qualifier, function_prefix, source_file):
headers = get_headers(ast)
headers.update(['<cmath>', '<cstdint>'])
- with open(target_file, 'w') as source_file:
- code = generate_c(ast)
- includes = "\n".join(["#include %s" % (include_file,) for include_file in headers])
- print(includes, file=source_file)
- print("#define RESTRICT %s" % (restrict_qualifier,), file=source_file)
- print("#define FUNC_PREFIX %s" % (function_prefix,), file=source_file)
- print('extern "C" { ', file=source_file)
- print(code, file=source_file)
- print('}', file=source_file)
+ code = generate_c(ast)
+ includes = "\n".join(["#include %s" % (include_file,) for include_file in headers])
+ print(includes, file=source_file)
+ print("#define RESTRICT %s" % (restrict_qualifier,), file=source_file)
+ print("#define FUNC_PREFIX %s" % (function_prefix,), file=source_file)
+ print('extern "C" { ', file=source_file)
+ print(code, file=source_file)
+ print('}', file=source_file)
def run_compile_step(command):
@@ -298,16 +297,18 @@ def compile_linux(ast, code_hash_str, src_file, lib_file):
compiler_config = get_compiler_config()
object_file = os.path.join(cache_config['object_cache'], code_hash_str + '.o')
- # Compilation
if not os.path.exists(object_file):
- generate_code(ast, compiler_config['restrict_qualifier'], '', src_file)
- compile_cmd = [compiler_config['command'], '-c'] + compiler_config['flags'].split()
- compile_cmd += ['-o', object_file, src_file]
- run_compile_step(compile_cmd)
+ with file_handle_for_atomic_write(src_file) as f:
+ generate_code(ast, compiler_config['restrict_qualifier'], '', f)
+ with atomic_file_write(object_file) as file_name:
+ compile_cmd = [compiler_config['command'], '-c'] + compiler_config['flags'].split()
+ compile_cmd += ['-o', file_name, src_file]
+ run_compile_step(compile_cmd)
# Linking
- run_compile_step([compiler_config['command'], '-shared', object_file, '-o', lib_file] +
- compiler_config['flags'].split())
+ with atomic_file_write(lib_file) as file_name:
+ run_compile_step([compiler_config['command'], '-shared', object_file, '-o', file_name] +
+ compiler_config['flags'].split())
def compile_windows(ast, code_hash_str, src_file, lib_file):
@@ -317,8 +318,8 @@ def compile_windows(ast, code_hash_str, src_file, lib_file):
object_file = os.path.join(cache_config['object_cache'], code_hash_str + '.obj')
# Compilation
if not os.path.exists(object_file):
- generate_code(ast, compiler_config['restrict_qualifier'],
- '__declspec(dllexport)', src_file)
+ with file_handle_for_atomic_write(src_file) as f:
+ generate_code(ast, compiler_config['restrict_qualifier'], '__declspec(dllexport)', f)
# /c compiles only, /EHsc turns of exception handling in c code
compile_cmd = ['cl.exe', '/c', '/EHsc'] + compiler_config['flags'].split()
diff --git a/utils.py b/utils.py
index 57abda263..bc7833629 100644
--- a/utils.py
+++ b/utils.py
@@ -1,3 +1,6 @@
+import os
+from tempfile import NamedTemporaryFile
+from contextlib import contextmanager
from typing import Mapping
@@ -34,3 +37,32 @@ def recursive_dict_update(d, u):
else:
d[k] = u[k]
return d
+
+
+@contextmanager
+def file_handle_for_atomic_write(file_path):
+ """Open temporary file object that atomically moves to destination upon exiting.
+
+ Allows reading and writing to and from the same filename.
+ The file will not be moved to destination in case of an exception.
+
+ Args:
+ file_path: path to file to be opened
+ """
+ target_folder = os.path.dirname(os.path.abspath(file_path))
+ with NamedTemporaryFile(delete=False, dir=target_folder, mode='w') as f:
+ try:
+ yield f
+ finally:
+ f.flush()
+ os.fsync(f.fileno())
+ os.rename(f.name, file_path)
+
+
+@contextmanager
+def atomic_file_write(file_path):
+ target_folder = os.path.dirname(os.path.abspath(file_path))
+ with NamedTemporaryFile(delete=False, dir=target_folder) as f:
+ f.file.close()
+ yield f.name
+ os.rename(f.name, file_path)
--
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