Use the faulthandler module's infrastructure to write a GIL-less
memory watchdog for timely stats collection.
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 62ad606..cce04aa 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -23,6 +23,7 @@
import sysconfig
import fnmatch
import logging.handlers
+import struct
try:
import _thread, threading
@@ -34,6 +35,10 @@
except ImportError:
multiprocessing = None
+try:
+ import faulthandler
+except ImportError:
+ faulthandler = None
try:
import zlib
@@ -1133,41 +1138,66 @@
raise ValueError('Memory limit %r too low to be useful' % (limit,))
max_memuse = memlimit
-def _memory_watchdog(start_evt, finish_evt, period=10.0):
- """A function which periodically watches the process' memory consumption
+class _MemoryWatchdog:
+ """An object which periodically watches the process' memory consumption
and prints it out.
"""
- # XXX: because of the GIL, and because the very long operations tested
- # in most bigmem tests are uninterruptible, the loop below gets woken up
- # much less often than expected.
- # The polling code should be rewritten in raw C, without holding the GIL,
- # and push results onto an anonymous pipe.
- try:
- page_size = os.sysconf('SC_PAGESIZE')
- except (ValueError, AttributeError):
+
+ def __init__(self):
+ self.procfile = '/proc/{pid}/statm'.format(pid=os.getpid())
+ self.started = False
+ self.thread = None
try:
- page_size = os.sysconf('SC_PAGE_SIZE')
+ self.page_size = os.sysconf('SC_PAGESIZE')
except (ValueError, AttributeError):
- page_size = 4096
- procfile = '/proc/{pid}/statm'.format(pid=os.getpid())
- try:
- f = open(procfile, 'rb')
- except IOError as e:
- warnings.warn('/proc not available for stats: {}'.format(e),
- RuntimeWarning)
- sys.stderr.flush()
- return
- with f:
- start_evt.set()
- old_data = -1
- while not finish_evt.wait(period):
- f.seek(0)
- statm = f.read().decode('ascii')
- data = int(statm.split()[5])
- if data != old_data:
- old_data = data
+ try:
+ self.page_size = os.sysconf('SC_PAGE_SIZE')
+ except (ValueError, AttributeError):
+ self.page_size = 4096
+
+ def consumer(self, fd):
+ HEADER = "l"
+ header_size = struct.calcsize(HEADER)
+ try:
+ while True:
+ header = os.read(fd, header_size)
+ if len(header) < header_size:
+ # Pipe closed on other end
+ break
+ data_len, = struct.unpack(HEADER, header)
+ data = os.read(fd, data_len)
+ statm = data.decode('ascii')
+ data = int(statm.split()[5])
print(" ... process data size: {data:.1f}G"
- .format(data=data * page_size / (1024 ** 3)))
+ .format(data=data * self.page_size / (1024 ** 3)))
+ finally:
+ os.close(fd)
+
+ def start(self):
+ if not faulthandler or not hasattr(faulthandler, '_file_watchdog'):
+ return
+ try:
+ rfd = os.open(self.procfile, os.O_RDONLY)
+ except OSError as e:
+ warnings.warn('/proc not available for stats: {}'.format(e),
+ RuntimeWarning)
+ sys.stderr.flush()
+ return
+ pipe_fd, wfd = os.pipe()
+ # _file_watchdog() doesn't take the GIL in its child thread, and
+ # therefore collects statistics timely
+ faulthandler._file_watchdog(rfd, wfd, 3.0)
+ self.started = True
+ self.thread = threading.Thread(target=self.consumer, args=(pipe_fd,))
+ self.thread.daemon = True
+ self.thread.start()
+
+ def stop(self):
+ if not self.started:
+ return
+ faulthandler._cancel_file_watchdog()
+ self.thread.join()
+
def bigmemtest(size, memuse, dry_run=True):
"""Decorator for bigmem tests.
@@ -1194,27 +1224,20 @@
"not enough memory: %.1fG minimum needed"
% (size * memuse / (1024 ** 3)))
- if real_max_memuse and verbose and threading:
+ if real_max_memuse and verbose and faulthandler and threading:
print()
print(" ... expected peak memory use: {peak:.1f}G"
.format(peak=size * memuse / (1024 ** 3)))
- sys.stdout.flush()
- start_evt = threading.Event()
- finish_evt = threading.Event()
- t = threading.Thread(target=_memory_watchdog,
- args=(start_evt, finish_evt, 0.5))
- t.daemon = True
- t.start()
- start_evt.set()
+ watchdog = _MemoryWatchdog()
+ watchdog.start()
else:
- t = None
+ watchdog = None
try:
return f(self, maxsize)
finally:
- if t:
- finish_evt.set()
- t.join()
+ if watchdog:
+ watchdog.stop()
wrapper.size = size
wrapper.memuse = memuse