From: "Ludovic Courtès" <ludo@gnu.org>
To: Christopher Baines <mail@cbaines.net>
Cc: 47283@debbugs.gnu.org
Subject: bug#47283: Performance regression in narinfo fetching
Date: Sun, 21 Mar 2021 22:22:10 +0100 [thread overview]
Message-ID: <87czvs19tp.fsf@gnu.org> (raw)
In-Reply-To: <874kh5d0rg.fsf@cbaines.net> (Christopher Baines's message of "Sat, 20 Mar 2021 20:32:35 +0000")
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Christopher Baines <mail@cbaines.net> skribis:
> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Indeed, there’s one place on the hot path where we install exception
>> handlers: in ‘http-multiple-get’ (from commit
>> 205833b72c5517915a47a50dbe28e7024dc74e57). I don’t think it’s needed,
>> is it? (But if it is, let’s find another approach, this one is
>> prohibitively expensive.)
>
> I think the exception handling has moved around, but I guess the
> exceptions that could be caught in http-multiple-get could happen,
> right? I am really just guessing here, as Guile doesn't help tell you
> about possible exceptions, and I haven't spent enough time to read all
> the possible code involved to find out if these are definitely possible.
Yeah.
Commit 205833b72c5517915a47a50dbe28e7024dc74e57 added a ‘catch’ block
that catches the same things as ‘with-cached-connection’ did (it would
be better to not duplicate it IMO). That includes EPIPE, gnutls-error,
bad-response & co.
Earlier, commit be5a75ebb5988b87b2392e2113f6590f353dd6cd (“substitute:
Reuse connections for '--query'.”) did not add such a ‘catch’ block in
‘http-multiple-get’. Instead, it wrapped its call in ‘do-fetch’ in
‘fetch-narinfos’:
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(define (do-fetch uri)
(case (and=> uri uri-scheme)
((http https)
- (let ((requests (map (cut narinfo-request url <>) paths)))
- (match (open-connection-for-uri/maybe uri)
- (#f
- '())
- (port
- (update-progress!)
;; Note: Do not check HTTPS server certificates to avoid depending
;; on the X.509 PKI. We can do it because we authenticate
;; narinfos, which provides a much stronger guarantee.
- (let ((result (http-multiple-get uri
+ (let* ((requests (map (cut narinfo-request url <>) paths))
+ (result (call-with-cached-connection uri
+ (lambda (port)
+ (if port
+ (begin
+ (update-progress!)
+ (http-multiple-get uri
handle-narinfo-response '()
requests
+ #:open-connection
+ open-connection-for-uri/cached
#:verify-certificate? #f
- #:port port)))
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This bit is still there in current ‘master’, so I think it’s not
necessary to catch these exceptions in ‘http-multiple-get’ itself, and I
would just remove the ‘catch’ wrap altogether.
WDYT?
Thanks,
Ludo’.
next prev parent reply other threads:[~2021-03-21 21:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-20 17:38 bug#47283: Performance regression in narinfo fetching Ludovic Courtès
2021-03-20 20:32 ` Christopher Baines
2021-03-21 0:48 ` Christopher Baines
2021-03-21 21:10 ` Ludovic Courtès
2021-03-21 21:22 ` Ludovic Courtès [this message]
2021-03-23 20:47 ` Christopher Baines
2021-03-24 14:51 ` Ludovic Courtès
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