* [Bug debuginfod/28339] New: groom/scan race condition
@ 2021-09-14 12:15 fche at redhat dot com
2021-09-15 17:33 ` [Bug debuginfod/28339] " fche at redhat dot com
0 siblings, 1 reply; 2+ messages in thread
From: fche at redhat dot com @ 2021-09-14 12:15 UTC (permalink / raw)
To: elfutils-devel
https://sourceware.org/bugzilla/show_bug.cgi?id=28339
Bug ID: 28339
Summary: groom/scan race condition
Product: elfutils
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: debuginfod
Assignee: fche at redhat dot com
Reporter: fche at redhat dot com
CC: elfutils-devel at sourceware dot org
Target Milestone: ---
debuginfod's scan and groom operations (thread_main_scanner,
thread_main_fts_source_paths) are intended to be mutually exclusive,
as a substitute for more complicated sql transaction batching. (This
is because scanning / grooming involves inserting or deleting data
from multiple related tables.)
The workq class that governs this in debuginfod.cxx has a problem: if
the workq just becomes empty, its sole entry pulled by a scanner thread
in response to a wait_front(), an 'idler' groomer thread is ALSO permitted
to run, because there is no indication as to when the scanner thread
operation finishes, only when it starts.
Extending the workq with a counter ("fronters") to track any active
scanning activity (even if the workq is empty) lets us block idlers
groomers a little longer.
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* [Bug debuginfod/28339] groom/scan race condition
2021-09-14 12:15 [Bug debuginfod/28339] New: groom/scan race condition fche at redhat dot com
@ 2021-09-15 17:33 ` fche at redhat dot com
0 siblings, 0 replies; 2+ messages in thread
From: fche at redhat dot com @ 2021-09-15 17:33 UTC (permalink / raw)
To: elfutils-devel
https://sourceware.org/bugzilla/show_bug.cgi?id=28339
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> ---
commit 2ff803956d6aaefeed3bc3f186da6fe666c7b1b6
Author: Frank Ch. Eigler <fche@redhat.com>
Date: Tue Sep 14 08:15:23 2021 -0400
PR28339: debuginfod: fix groom/scan race condition on just-emptied queue
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