Read-sequence is slow?

Raymond Toy <[email protected]> Wed, 8 Apr 2026 09:21:37 -0700
Newsgroups gmane.lisp.gcl.devel
Message-ID <[email protected]> 
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I have this routine:

|(defun slurp-bytes (filename) "Return the entire contents of FILENAME 
as a (unsigned-byte 8) vector. Results are cached in *bytes-cache* so 
each file is read only once." (or (gethash filename *bytes-cache*) (setf 
(gethash filename *bytes-cache*) (with-open-file (s filename :direction 
:input :element-type '(unsigned-byte 8)) (let* ((len (file-length s)) 
(buf (make-array len :element-type '(unsigned-byte 8)))) (read-sequence 
buf s) buf))))) |

When reading maxima.info-1 (1030671 bytes), it takes a very long time 
(several seconds). Is there anyway to speed this up? I would have 
expected reading a bunch of bytes from a file via read-sequence would be 
very fast.

&#8203;
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    <div class=3D"markdown-here-wrapper">
      <p style=3D"margin-bottom: 19.2px; margin-top: 0px;">I have this
        routine:</p>
      <pre
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 padding-right: 11.2px; padding-top: 8px;">
(defun slurp-bytes (filename)
  "Return the entire contents of FILENAME as a (unsigned-byte 8) vector.
   Results are cached in *bytes-cache* so each file is read only once."
  (or (gethash filename *bytes-cache*)
      (setf (gethash filename *bytes-cache*)
            (with-open-file (s filename :direction :input
                                        :element-type '(unsigned-byte 8))=

              (let* ((len (file-length s))
                     (buf (make-array len :element-type '(unsigned-byte 8=
))))
                (read-sequence buf s)
                buf)))))
</code></pre>
      <p style=3D"margin-bottom: 19.2px; margin-top: 0px;">When reading
        maxima.info-1 (1030671 bytes), it takes a very long time
        (several seconds). Is there anyway to speed this up? I would
        have expected reading a bunch of bytes from a file via
        read-sequence would be very fast.</p>
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