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Re: [PATCH for-4.17 v3 13/15] tools/ocaml/xenstored: set uncaught exception handler


  • To: Edwin Torok <edvin.torok@xxxxxxxxxx>
  • From: Christian Lindig <christian.lindig@xxxxxxxxxx>
  • Date: Wed, 9 Nov 2022 14:07:45 +0000
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  • Thread-topic: [PATCH for-4.17 v3 13/15] tools/ocaml/xenstored: set uncaught exception handler


> On 8 Nov 2022, at 15:34, Edwin Török <edvin.torok@xxxxxxxxxx> wrote:
> 
> Helps debug fatal errors during live update
> 
> Previously this would've just gone to /dev/null, because:
> * daemonize reopens stderr as /dev/null
> * systemd redirects stderr to /dev/null too
> 
> Previously the only way to debug this was to manually run oxenstored with
> --no-fork, but when you have a fatal error and oxenstored just
> disappears you'd want to know why.
> There has been at least one observed instance of a bug where oxenstored
> just disappeared inexplicably (it was believed due to an OOM exception).
> 
> Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
> ---
> Reason for inclusion in 4.17:
> - avoids losing crucial information during a fatal error (e.g. during
>  live update)

Acked-by: Christian Lindig <christian.lindig@xxxxxxxxxx>

> +let print_flush msg =
> +  prerr_endline msg;
> +  flush stderr

The flush is not required because prerr_endline does it implicitly.



 


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