# This tool lists processes that lock memory pages from swapping to disk.
 
 import re
 
 import psutil
 
 

 LCK_SUMMARY_REGEX = re.compile(
     "^VmLck:\s+(?P<locked>[\d]+)\s+kB", re.MULTILINE)

 
 
 def main():
     try:

         print(_get_report())

     except Exception as e:

         print("Failure listing processes locking memory: %s" % str(e))
         raise

 
 
 def _get_report():
     mlock_users = []
     for proc in psutil.process_iter():
         # sadly psutil does not expose locked pages info, that's why we

         # iterate over the /proc/%pid/status files manually

         try:

             s = open("%s/%d/status" % (psutil.PROCFS_PATH, proc.pid), 'r')
         except EnvironmentError:
             continue
         with s:
             for line in s:
                 result = LCK_SUMMARY_REGEX.search(line)
                 if result:
                     locked = int(result.group('locked'))
                     if locked:
                         mlock_users.append({'name': proc.name(),
                                             'pid': proc.pid,
                                             'locked': locked})

 
     # produce a single line log message with per process mlock stats
     if mlock_users:
         return "; ".join(
             "[%(name)s (pid:%(pid)s)]=%(locked)dKB" % args
             # log heavy users first
             for args in sorted(mlock_users, key=lambda d: d['locked'])
         )
     else:
         return "no locked memory"
 
 
 if __name__ == "__main__":
     main()