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41 lines
1,016 B
Scheme
41 lines
1,016 B
Scheme
;;;; Example of using multiple threads to sum a variable without synchronization.
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;;;; Returns inconsistent and wrong results due to a lack of thread coordination.
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(import (scheme base)
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(scheme read)
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(scheme write)
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(srfi 18))
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(define *sum* 0)
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(define (sum-loop n)
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(set! *sum* (+ *sum* 1))
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(if (zero? n)
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'done
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(sum-loop (- n 1))))
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(define (sum-entry-pt)
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(sum-loop (* 100 100 100)))
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;; Thread - Do something, then let main thread know when we are done
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(define t1 (make-thread sum-entry-pt))
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(define t2 (make-thread sum-entry-pt))
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(define t3 (make-thread sum-entry-pt))
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(define t4 (make-thread sum-entry-pt))
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(define t5 (make-thread sum-entry-pt))
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(define t6 (make-thread sum-entry-pt))
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(thread-start! t1)
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(thread-start! t2)
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(thread-start! t3)
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(thread-start! t4)
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(thread-start! t5)
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(thread-start! t6)
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(thread-join! t1)
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(thread-join! t2)
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(thread-join! t3)
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(thread-join! t4)
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(thread-join! t5)
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(thread-join! t6)
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(display "main thread done, sum = ")
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(display *sum*)
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(newline)
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