3f23ceb8e7
The 8 threads whose [rbx] did not resolve to a vtable were never in XObject::Wait. The backtrace grep matched WaitMultiple as a substring, and there %rbx is the XObject** array (mov %rsi,%rbx) with the count in %ebp, so [rbx] is objects[0] -- an object pointer, needing a second deref -- not a vtable. The unwind restored rbx correctly for all 18. freeze_waitobj.sh now takes the function and frame index from the backtrace and applies the matching read, and captures twice in one run (healthy and after the ~270s black-screen) so the comparison is within-run. waitobj_report.py tabulates both and diffs them, discarding any value info symbol cannot resolve.
75 lines
2.9 KiB
Python
Executable File
75 lines
2.9 KiB
Python
Executable File
#!/usr/bin/env python3
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"""Turn the gdb wait-object dumps into a table, discarding what does not check out.
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The two waiting functions do not put the same thing in %rbx (see
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freeze_waitobj.sh), so they are parsed separately:
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Wait rbx = this -> [rbx] is the vtable
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WaitMultiple rbx = XObject** -> [[rbx+8i]] is object i's vtable
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ebp = count -> entries past the count are garbage
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Every reading is validated the same way: gdb's `info symbol` must resolve it to
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a `vtable for ...` symbol. A polymorphic object's first word always is one, so
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anything else is a misread and is COUNTED but not interpreted. That check is
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what the reading is worth -- without it a stale register looks like a result.
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"""
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import re, sys, collections
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VT = re.compile(r'vtable for ([\w:]+) \+ (\d+)')
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HDR = re.compile(r'=== (\w+) T(\d+) (Wait|WaitMultiple) f(\d+) ===')
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def parse(tag):
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"""-> list of (thread, kind, count, [vtable-or-None per slot])"""
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try:
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txt = open('/tmp/fz-obj-%s.txt' % tag, errors='replace').read()
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except FileNotFoundError:
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return []
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out, cur = [], None
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for line in txt.splitlines():
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line = line.replace('(gdb) ', '')
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h = HDR.search(line)
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if h:
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if cur: out.append(cur)
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cur = dict(th=h.group(2), kind=h.group(3), count=None, slots=[], bad=0)
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continue
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if not cur: continue
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m = re.search(r'rbp\s+0x[0-9a-f]+\s+(\d+)', line)
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if m: cur['count'] = int(m.group(1)) & 0xffffffff
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if 'info symbol' in line or line.startswith('$'): continue
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v = VT.search(line)
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if v:
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cur['slots'].append(v.group(1))
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elif 'No symbol matches' in line:
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cur['slots'].append(None); cur['bad'] += 1
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if cur: out.append(cur)
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return out
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def report(tag):
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recs = parse(tag)
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print('=== %s: %d wait frames ===' % (tag, len(recs)))
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if not recs: return collections.Counter()
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tally = collections.Counter()
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for r in recs:
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n = r['count'] if r['kind'] == 'WaitMultiple' and r['count'] else len(r['slots'])
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n = min(n, len(r['slots']))
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live = r['slots'][:n]
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for s in live:
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tally[s if s else '<unresolved>'] += 1
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print(' T%-4s %-13s count=%-4s %s' % (
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r['th'], r['kind'], r['count'] if r['count'] is not None else '-',
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', '.join(s or '?' for s in live) or '(nothing readable)'))
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print(' --- objects waited on:')
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for k, c in tally.most_common():
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print(' %-45s %d' % (k, c))
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return tally
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if __name__ == '__main__':
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tallies = {t: report(t) for t in (sys.argv[1:] or ['healthy'])}
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if len(tallies) > 1:
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a, b = list(tallies)
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print('=== %s -> %s ===' % (a, b))
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keys = set(tallies[a]) | set(tallies[b])
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for k in sorted(keys):
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x, y = tallies[a][k], tallies[b][k]
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print(' %-45s %3d -> %-3d %s' % (k, x, y, '' if x == y else ' CHANGED'))
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