On Nov 17, 10:34 am, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > Hi folks - wondering if anyone has any pointers on troubleshooting > garbage collection. My colleagues and I are running into an > interesting problem: > > Intermittently, we get into a situation where the garbage collection > code is running in an infinite loop. The data structures within the > garbage collector have been corrupted, but it is unclear how or why. > The problem is extremely difficult to reproduce consistently as it is > unpredictable. > > The infinite loop itself occurs in gcmodule.c, update_refs. After > hitting this in the debugger a couple of times, it appears that that > one of the nodes in the second or third generation list contains a > pointer to the first generation head node. The first generation was > cleared shortly before the call into this function, so it contains a > prev and next which point to itself. Once this loop hits that node, > it spins infinitely. > > Chances are another module we're depending on has done something > hinkey with GC. The challenge is tracking that down. If anyone has > seen something like this before and has either pointers to specific GC > usage issues that can create this behavior or some additional thoughts > on tricks to track it down to the offending module, they would be most > appreciated. > > You can assume we've done some of the "usual" things - hacking up > gcmodule to spit information when the condition occurs, various > headstands and gymnastics in an attempt to identify reliable steps to > reproduce - the challenge is the layers of indirection that we think > are likely present between the manifestation of the problem and the > module that produced it.
Does "usual things" also include compiling with --with-pydebug? You could also try the various memory debuggers. A refcounting error is the first thing that comes to mind, although I can't see off hand how this specific problem would come about. Are you using threading at all? Do you see any pattern to the types that have the bogus pointers? -- Adam Olsen, aka Rhamphoryncus -- http://mail.python.org/mailman/listinfo/python-list
