Re: [Chicken-janitors] #1173: Symbols held in GC-roots are sometimes collected in "symbol-gc" mode

[Chicken Trac]

#1173: Symbols held in GC-roots are sometimes collected in "symbol-gc" mode
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  Reporter:  felix           |      Owner:
      Type:  defect          |     Status:  new
  Priority:  major           |  Milestone:  5.0
 Component:  core libraries  |    Version:  4.9.x
Resolution:                  |   Keywords:
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Comment (by LemonBoy):

 After some brief experimentation I think that the root cause is the fact
 that the symbol-gc greedily wipes '''all''' the symbols from the table,
 including the static ones that hold the names for the exported symbols.
 Back to this specific case, {{{##sys#load-extension}}} is failing because
 an eq? comparison doesn't hold anymore (I think it was one of the memq,
 sadly I didn't write any note) and end up printing the error above.

 As a possible fix I could devise two possible scenarios:
 * Make the static symbols have a ∞ reference count (so that now the
 counter has 4 possible states: 0, 1, 1+, ∞)
 * Avoid static symbols when evicting the symbols, you can recognize that a
 symbol's static if the slot-1 string resides outside the chicken heap.

 I did implement the latter since it was easier and fixed this particular
 crash, I didn't test it much though.

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Ticket URL: <http://bugs.call-cc.org/ticket/1173#comment:4>
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