I'm wondering what writing the backtrace to a /tmp/file and doing a cat -nA on it would show. (to get the traceback bits presented by independent alternate formatting machinery from what produced what you've seen so far).
On +2025-02-11 19:06:46 +0000, Christopher Baines wrote: > Christopher Baines <m...@cbaines.net> writes: > > > Christopher Baines <m...@cbaines.net> writes: > > > >> I've been seeing some strange occasional errors for a while now. > > > > ... > > > >> I'm not sure what the 84 means? If I'm picking out the characters that > >> have failed to be encoded, I'm not sure why some of these would fail > >> (like space or w)? > >> > >> Unfortunately I'm not sure how to reproduce this. Suspendable ports > >> might be a factor here as that is probably in use. > > > > Still seeing these errors, including today. I've managed to stumble on a > > reliable and somewhat minimal way of reproducing them: > > Here's a slightly simplified version with some comments: > > (use-modules (ice-9 binary-ports) > (rnrs bytevectors) > (ice-9 exceptions) > (ice-9 threads) > (system repl debug)) > > (setvbuf (current-output-port) 'line) > (setvbuf (current-error-port) 'line) > > (simple-format (current-error-port) > "current-output-port: ~A (encoding: ~A)\n\n" > (current-output-port) > (port-encoding (current-output-port))) > > (for-each > (lambda (i) > (call-with-new-thread > (lambda () > (with-exception-handler > (lambda (exn) > (let ((stack (make-stack #t))) > (print-frames (stack->vector stack) > (current-error-port) > #:count (stack-length stack)) > (print-exception > (current-error-port) > (stack-ref stack 3) > '%exception > (list exn))) > (force-output (current-error-port)) > > (primitive-exit 1)) > (lambda () > (while #t > (with-exception-handler > (lambda (exn) > ;; The put-char error seems to happen around here > (simple-format (current-output-port) > "exception: ~A\n" > exn) > #f) > (lambda () > (with-throw-handler #t > (lambda () > ;; Cause some error, I think any error will do > (+ 'a 1)) > (lambda (key . args) > (let* ((stack (make-stack #t 3)) > (backtrace > (call-with-output-string > (lambda (port) > (display-backtrace stack port) > (newline port))))) > (display > ;; Printing the backtrace seems significant, > ;; other strings don't seem to reproduce the > ;; behaviour > backtrace > (current-output-port)) > #f)))) > #:unwind? #t))))))) > (iota 2)) > > (sleep 60)
