Utility script for setting access pattern of MySQL log files to recycle buffer cache

free-buffer-cache.py

#!/usr/bin/env python

"""
Utility script for setting access pattern of MySQL log files to recycle
buffer cache
"""

import os
import sys
import glob
import ctypes
import ctypes.util

POSIX_FADV_DONTNEED = 4

libc = ctypes.CDLL(ctypes.util.find_library('c'))

def posix_fadvise(fd, offset, length, advice):
    return libc.posix_fadvise(fd,
                              ctypes.c_uint64(offset),
                              ctypes.c_uint64(length),
                              advice)

LOG_PATTERNS = (
    '/log/mysql-*/*logs/*',
    '/data/mysql-*/*logs/*',
    '/backup/mysql-*/*logs/*',
    '/backup/mysql-*/*/*ibd',
    '/backup/mysql-*/*/*MY*',
)

for pattern in LOG_PATTERNS:
    for log in glob.glob(pattern):
        try:
            fd = os.open(log, os.O_RDONLY)
        except OSError, err:
            print >> sys.stderr, err
            continue

        if posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED) != 0:
            print >> sys.stderr, 'Failed to posix_fadvise for', log