Opened 10 years ago

Last modified 10 years ago

#905 closed defect

Unreliable behavior of hash tables with symbols as keys (regression wrt 4.7.4) — at Version 2

Reported by: Ivan Raikov Owned by:
Priority: critical Milestone: 4.9.0
Component: core libraries Version: 4.8.x
Keywords: Cc:
Estimated difficulty:

Description (last modified by Ivan Raikov)

The nemo program relies heavily on performing transformations over hash tables with symbols as keys. It works fine with Chicken 4.7.4, but unfortunately there seems to have been a regression in 4.8.0rc1, which results in hash-table-exists? and hash-table-ref failing to find any of the existing keys in the table after a number of transformations have been performed.
The following code reproduces the issue:

(use srfi-1 srfi-69)

(define t (make-hash-table hash: symbol-hash))

(hash-table-set! t 'k1 1)
(hash-table-ref t 'k1)

  (lambda (k v)
    (printf "hash-table-set! ~A ~A~%" k v)
    (hash-table-set! t k v))
  (list-tabulate 10 (lambda (i) (gensym 'k)))
  (list-tabulate 10 (lambda (i) i))

(print (hash-table->alist t))
(print (hash-table-ref t 'k15))

Perhaps the hash tables stop working after some garbage collections have been performed. This issue is not entirely new; nemo previously used the environments egg, which was also exhibiting similar unreliable behavior, so I had resorted to using strings instead of symbols as keys. Any advice on how to debug this would be appreciated.

Change History (2)

comment:1 Changed 10 years ago by Ivan Raikov

Description: modified (diff)

comment:2 Changed 10 years ago by Ivan Raikov

Description: modified (diff)
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