Hello, Andy Wingo <[EMAIL PROTECTED]> writes:
> ERROR: srfi-18.test: thread-start!: > thread activates only after start > - arguments: ((syntax-error "memoization" > "In file ~S, line ~S: ~A ~S in expression ~S." > ("/home/lilydev/vc/guile/srfi/srfi-18.scm" 135 > "Bad binding" ct > (let (ct (current-thread)) > [EMAIL PROTECTED] (or (hashq-ref > thread-exception-handlers ct) > (hashq-set! thread-exception-handlers ct > (list initial-handler))))) #f)) I'm seeing this as well, but it's a [EMAIL PROTECTED]' here (single-binding `let's are memoized as [EMAIL PROTECTED]'): ((syntax-error "memoization" "In file ~S, line ~S: ~A ~S in expression ~S." ("/home/ludo/src/guile/srfi/srfi-18.scm" 138 "Bad binding" ct ([EMAIL PROTECTED] (ct (#<variable b7d28110 value: #<primitive-procedure current-thread>>)) ([EMAIL PROTECTED] (#<variable b7d2ad88 value: #<primitive-procedure hashq-ref>> #<variable 839df08 value: #<weak-key-hash-table 1/31>> [EMAIL PROTECTED]) (#<variable b7d2adc0 value: #<primitive-procedure hashq-set!>> #<variable 839df08 value: #<weak-key-hash-table 1/31>> [EMAIL PROTECTED] (#<variable b7d2c498 value: #<primitive-procedure list>> #<variable 839d130 value: #<procedure initial-handler (obj)>>)) ))) #f)) It can be reproduced, but very infrequently, with this program: (use-modules (ice-9 threads)) (define (foo x y) (let ((z (+ x y))) (let ((a (+ z 1))) (let ((b (- a 2))) (let ((c (* b 3))) c))))) (define (entry) (foo 1 2)) (for-each (lambda (i) (make-thread entry)) (iota 123)) My explanation is that the `let*' memoizer, aka. `scm_m_letstar ()', is not thread-safe; it's clearly not atomic, and it's of course not protected by a mutex or so. I can't think of any simple fix. `scm_m_letstar ()' could be made atomic by having it duplicate the input list instead of modifying it directly; it could then atomically update the input. However, allocating cells during memoization wouldn't be a good idea performance-wise. Thanks, Ludo'.