* [Bug debuginfod/28249] New: httpd-buildid-after-you gadget locks on wrong url
@ 2021-08-19 16:02 fche at redhat dot com
2021-08-19 17:14 ` [Bug debuginfod/28249] " fche at redhat dot com
0 siblings, 1 reply; 2+ messages in thread
From: fche at redhat dot com @ 2021-08-19 16:02 UTC (permalink / raw)
To: elfutils-devel
https://sourceware.org/bugzilla/show_bug.cgi?id=28249
Bug ID: 28249
Summary: httpd-buildid-after-you gadget locks on wrong url
Product: elfutils
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: debuginfod
Assignee: unassigned at sourceware dot org
Reporter: fche at redhat dot com
CC: elfutils-devel at sourceware dot org
Target Milestone: ---
bug #27673 added a "after-you" waiting system into debuginfod, which is
intended to prevent the server from trying to service multiple concurrent
requests for the exact same debuginfo artifact. This saves wear & tear & time,
as the non-first queries can use the fdcache to fish out the result, rather
than decompressing etc. again.
Unfortunately, the code has a one-liner bug. It uses the string "/buildid" as
the unique key, not the whole URL, so it in effect limits debuginfod to
servicing exactly one buildid request at a time, which was not intentional.
02144 unique_set_reserver<string> after_you(busy_urls, url1);
url1 is the wrong key. :-(
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* [Bug debuginfod/28249] httpd-buildid-after-you gadget locks on wrong url
2021-08-19 16:02 [Bug debuginfod/28249] New: httpd-buildid-after-you gadget locks on wrong url fche at redhat dot com
@ 2021-08-19 17:14 ` fche at redhat dot com
0 siblings, 0 replies; 2+ messages in thread
From: fche at redhat dot com @ 2021-08-19 17:14 UTC (permalink / raw)
To: elfutils-devel
https://sourceware.org/bugzilla/show_bug.cgi?id=28249
Frank Ch. Eigler <fche at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> ---
merging obvious patch:
commit 89b1a4e8793e0379e386da313c1bd90080390877 (HEAD -> master)
Author: Frank Ch. Eigler <fche@redhat.com>
Date: Thu Aug 19 13:11:11 2021 -0400
PR28249: correct debuginfod after-you locking
The initial code for bug #27673 accidentally nuked all buildid service
concurrency, not just identical concurrent requests. Correct this
with one-liner patch. Observing the effect in the automated testsuite
is difficult, so hand-tested against large requests and short ones,
run in an interleaved way.
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
index 4ddd92558533..fca07f61954f 100644
--- a/debuginfod/debuginfod.cxx
+++ b/debuginfod/debuginfod.cxx
@@ -2141,7 +2141,7 @@ handler_cb (void * /*cls*/,
struct timespec tsay_start, tsay_end;
clock_gettime (CLOCK_MONOTONIC, &tsay_start);
static unique_set<string> busy_urls;
- unique_set_reserver<string> after_you(busy_urls, url1);
+ unique_set_reserver<string> after_you(busy_urls, url_copy);
clock_gettime (CLOCK_MONOTONIC, &tsay_end);
afteryou = (tsay_end.tv_sec - tsay_start.tv_sec) + (tsay_end.tv_nsec
- tsay_start.tv_nsec)/1.e9;
add_metric ("thread_busy", "role", "http-buildid-after-you", -1);
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