From: "fche at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: elfutils-devel@sourceware.org
Subject: [Bug debuginfod/28339] New: groom/scan race condition
Date: Tue, 14 Sep 2021 12:15:16 +0000 [thread overview]
Message-ID: <bug-28339-10460@http.sourceware.org/bugzilla/> (raw)
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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next reply other threads:[~2021-09-14 12:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 12:15 fche at redhat dot com [this message]
2021-09-15 17:33 ` [Bug debuginfod/28339] " fche at redhat dot com
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