Add RSS memory status collecting routine

Added RSS memory status collecting routine which parses file:

  /sys/fs/cgroup/memory/memory.stat

for RSS value. For this routine use added test-run new option:

  --collect-statistics

which should be used to use this routine.

Part of tarantool/tarantool-qa#98

Author: avtikhon

lib/options.py

@@ -271,6 +271,14 @@ def __init__(self):
                 default=os.environ.get("MEMTX_ALLOCATOR", "small"),
                 help="""Memtx allocator type for tests""")
 
+        parser.add_argument(
+                "--collect-statistics",
+                dest="collect_statistics",
+                action="store_true",
+                default=False,
+                help="""Collect memory/disk host statistics usage.
+                Default: false.""")
+
         # XXX: We can use parser.parse_intermixed_args() on
         # Python 3.7 to understand commands like
         # ./test-run.py foo --exclude bar baz

lib/utils.py

@@ -1,4 +1,5 @@
 import os
+import re
 import sys
 import collections
 import signal
@@ -233,6 +234,19 @@ def format_process(pid):
     return 'process %d [%s; %s]' % (pid, status, cmdline)
 
 
+def get_mem_stat_rss():
+    rss = 'unknown'
+    pat = re.compile(r"^total_rss .*")
+    try:
+        with open('/sys/fs/cgroup/memory/memory.stat', 'r') as f:
+            for line in f:
+                if pat.match(line) is not None:
+                    rss = line.split(' ')[1]
+    except (OSError, IOError):
+        pass
+    return rss
+
+
 def set_fd_cloexec(socket):
     flags = fcntl.fcntl(socket, fcntl.F_GETFD)
     fcntl.fcntl(socket, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC)