| 1 | #! /usr/bin/env python
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| 2 |
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| 3 | """
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| 4 | combinerefs path
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| 5 |
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| 6 | A helper for analyzing PYTHONDUMPREFS output.
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| 7 |
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| 8 | When the PYTHONDUMPREFS envar is set in a debug build, at Python shutdown
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| 9 | time Py_Finalize() prints the list of all live objects twice: first it
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| 10 | prints the repr() of each object while the interpreter is still fully intact.
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| 11 | After cleaning up everything it can, it prints all remaining live objects
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| 12 | again, but the second time just prints their addresses, refcounts, and type
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| 13 | names (because the interpreter has been torn down, calling repr methods at
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| 14 | this point can get into infinite loops or blow up).
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| 15 |
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| 16 | Save all this output into a file, then run this script passing the path to
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| 17 | that file. The script finds both output chunks, combines them, then prints
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| 18 | a line of output for each object still alive at the end:
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| 19 |
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| 20 | address refcnt typename repr
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| 21 |
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| 22 | address is the address of the object, in whatever format the platform C
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| 23 | produces for a %p format code.
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| 24 |
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| 25 | refcnt is of the form
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| 26 |
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| 27 | "[" ref "]"
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| 28 |
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| 29 | when the object's refcount is the same in both PYTHONDUMPREFS output blocks,
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| 30 | or
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| 31 |
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| 32 | "[" ref_before "->" ref_after "]"
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| 33 |
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| 34 | if the refcount changed.
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| 35 |
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| 36 | typename is object->ob_type->tp_name, extracted from the second PYTHONDUMPREFS
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| 37 | output block.
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| 38 |
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| 39 | repr is repr(object), extracted from the first PYTHONDUMPREFS output block.
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| 40 | CAUTION: If object is a container type, it may not actually contain all the
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| 41 | objects shown in the repr: the repr was captured from the first output block,
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| 42 | and some of the containees may have been released since then. For example,
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| 43 | it's common for the line showing the dict of interned strings to display
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| 44 | strings that no longer exist at the end of Py_Finalize; this can be recognized
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| 45 | (albeit painfully) because such containees don't have a line of their own.
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| 46 |
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| 47 | The objects are listed in allocation order, with most-recently allocated
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| 48 | printed first, and the first object allocated printed last.
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| 49 |
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| 50 |
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| 51 | Simple examples:
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| 52 |
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| 53 | 00857060 [14] str '__len__'
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| 54 |
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| 55 | The str object '__len__' is alive at shutdown time, and both PYTHONDUMPREFS
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| 56 | output blocks said there were 14 references to it. This is probably due to
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| 57 | C modules that intern the string "__len__" and keep a reference to it in a
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| 58 | file static.
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| 59 |
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| 60 | 00857038 [46->5] tuple ()
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| 61 |
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| 62 | 46-5 = 41 references to the empty tuple were removed by the cleanup actions
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| 63 | between the times PYTHONDUMPREFS produced output.
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| 64 |
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| 65 | 00858028 [1025->1456] str '<dummy key>'
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| 66 |
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| 67 | The string '<dummy key>', which is used in dictobject.c to overwrite a real
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| 68 | key that gets deleted, grew several hundred references during cleanup. It
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| 69 | suggests that stuff did get removed from dicts by cleanup, but that the dicts
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| 70 | themselves are staying alive for some reason. """
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| 71 |
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| 72 | import re
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| 73 | import sys
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| 74 |
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| 75 | # Generate lines from fileiter. If whilematch is true, continue reading
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| 76 | # while the regexp object pat matches line. If whilematch is false, lines
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| 77 | # are read so long as pat doesn't match them. In any case, the first line
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| 78 | # that doesn't match pat (when whilematch is true), or that does match pat
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| 79 | # (when whilematch is false), is lost, and fileiter will resume at the line
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| 80 | # following it.
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| 81 | def read(fileiter, pat, whilematch):
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| 82 | for line in fileiter:
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| 83 | if bool(pat.match(line)) == whilematch:
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| 84 | yield line
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| 85 | else:
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| 86 | break
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| 87 |
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| 88 | def combine(fname):
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| 89 | f = file(fname)
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| 90 | fi = iter(f)
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| 91 |
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| 92 | for line in read(fi, re.compile(r'^Remaining objects:$'), False):
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| 93 | pass
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| 94 |
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| 95 | crack = re.compile(r'([a-zA-Z\d]+) \[(\d+)\] (.*)')
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| 96 | addr2rc = {}
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| 97 | addr2guts = {}
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| 98 | before = 0
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| 99 | for line in read(fi, re.compile(r'^Remaining object addresses:$'), False):
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| 100 | m = crack.match(line)
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| 101 | if m:
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| 102 | addr, addr2rc[addr], addr2guts[addr] = m.groups()
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| 103 | before += 1
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| 104 | else:
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| 105 | print '??? skipped:', line
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| 106 |
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| 107 | after = 0
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| 108 | for line in read(fi, crack, True):
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| 109 | after += 1
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| 110 | m = crack.match(line)
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| 111 | assert m
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| 112 | addr, rc, guts = m.groups() # guts is type name here
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| 113 | if addr not in addr2rc:
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| 114 | print '??? new object created while tearing down:', line.rstrip()
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| 115 | continue
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| 116 | print addr,
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| 117 | if rc == addr2rc[addr]:
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| 118 | print '[%s]' % rc,
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| 119 | else:
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| 120 | print '[%s->%s]' % (addr2rc[addr], rc),
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| 121 | print guts, addr2guts[addr]
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| 122 |
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| 123 | f.close()
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| 124 | print "%d objects before, %d after" % (before, after)
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| 125 |
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| 126 | if __name__ == '__main__':
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| 127 | combine(sys.argv[1])
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