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+#! /usr/bin/env python
+
+"""
+combinerefs path
+
+A helper for analyzing PYTHONDUMPREFS output.
+
+When the PYTHONDUMPREFS envar is set in a debug build, at Python shutdown
+time Py_Finalize() prints the list of all live objects twice: first it
+prints the repr() of each object while the interpreter is still fully intact.
+After cleaning up everything it can, it prints all remaining live objects
+again, but the second time just prints their addresses, refcounts, and type
+names (because the interpreter has been torn down, calling repr methods at
+this point can get into infinite loops or blow up).
+
+Save all this output into a file, then run this script passing the path to
+that file. The script finds both output chunks, combines them, then prints
+a line of output for each object still alive at the end:
+
+ address refcnt typename repr
+
+address is the address of the object, in whatever format the platform C
+produces for a %p format code.
+
+refcnt is of the form
+
+ "[" ref "]"
+
+when the object's refcount is the same in both PYTHONDUMPREFS output blocks,
+or
+
+ "[" ref_before "->" ref_after "]"
+
+if the refcount changed.
+
+typename is object->ob_type->tp_name, extracted from the second PYTHONDUMPREFS
+output block.
+
+repr is repr(object), extracted from the first PYTHONDUMPREFS output block.
+CAUTION: If object is a container type, it may not actually contain all the
+objects shown in the repr: the repr was captured from the first output block,
+and some of the containees may have been released since then. For example,
+it's common for the line showing the dict of interned strings to display
+strings that no longer exist at the end of Py_Finalize; this can be recognized
+(albeit painfully) because such containees don't have a line of their own.
+
+The objects are listed in allocation order, with most-recently allocated
+printed first, and the first object allocated printed last.
+
+
+Simple examples:
+
+ 00857060 [14] str '__len__'
+
+The str object '__len__' is alive at shutdown time, and both PYTHONDUMPREFS
+output blocks said there were 14 references to it. This is probably due to
+C modules that intern the string "__len__" and keep a reference to it in a
+file static.
+
+ 00857038 [46->5] tuple ()
+
+46-5 = 41 references to the empty tuple were removed by the cleanup actions
+between the times PYTHONDUMPREFS produced output.
+
+ 00858028 [1025->1456] str '<dummy key>'
+
+The string '<dummy key>', which is used in dictobject.c to overwrite a real
+key that gets deleted, grew several hundred references during cleanup. It
+suggests that stuff did get removed from dicts by cleanup, but that the dicts
+themselves are staying alive for some reason. """
+
+import re
+import sys
+
+# Generate lines from fileiter. If whilematch is true, continue reading
+# while the regexp object pat matches line. If whilematch is false, lines
+# are read so long as pat doesn't match them. In any case, the first line
+# that doesn't match pat (when whilematch is true), or that does match pat
+# (when whilematch is false), is lost, and fileiter will resume at the line
+# following it.
+def read(fileiter, pat, whilematch):
+ for line in fileiter:
+ if bool(pat.match(line)) == whilematch:
+ yield line
+ else:
+ break
+
+def combine(fname):
+ f = file(fname)
+ fi = iter(f)
+
+ for line in read(fi, re.compile(r'^Remaining objects:$'), False):
+ pass
+
+ crack = re.compile(r'([a-zA-Z\d]+) \[(\d+)\] (.*)')
+ addr2rc = {}
+ addr2guts = {}
+ before = 0
+ for line in read(fi, re.compile(r'^Remaining object addresses:$'), False):
+ m = crack.match(line)
+ if m:
+ addr, addr2rc[addr], addr2guts[addr] = m.groups()
+ before += 1
+ else:
+ print '??? skipped:', line
+
+ after = 0
+ for line in read(fi, crack, True):
+ after += 1
+ m = crack.match(line)
+ assert m
+ addr, rc, guts = m.groups() # guts is type name here
+ if addr not in addr2rc:
+ print '??? new object created while tearing down:', line.rstrip()
+ continue
+ print addr,
+ if rc == addr2rc[addr]:
+ print '[%s]' % rc,
+ else:
+ print '[%s->%s]' % (addr2rc[addr], rc),
+ print guts, addr2guts[addr]
+
+ f.close()
+ print "%d objects before, %d after" % (before, after)
+
+if __name__ == '__main__':
+ combine(sys.argv[1])