From 31d6b1fe74ab89138b4d256742997b730dc5cba8 Mon Sep 17 00:00:00 2001 From: "Frank Ch. Eigler" Date: Mon, 15 Aug 2022 06:20:10 -0400 Subject: [PATCH] PR29474: debuginfod MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previous code sometimes confused debuginfod with concurrent queries targeting the same RPM. One thread fetching & prefetching, the other thread misinterpreted the sudden presence of its target file in the fdcache as a mere unnecessary prefetch duplicate. But if it was the other thread's target file, previous code would -skip- it completely, resulting in a 404 error. New code allows the other thread to also decompress the target file and return it, and still continue to its own prefetching process for other files. There's a performance trade-off here. Another option would be for the other thread to check the fdcache regularly and abort its own prefetch/fetch/prefetch loop early in case of a sudden target file hit. That'd save CPU probably but it'd stop prefetching of later segments of the input archive, which could save future time. Automated testing is too time/load sensitive to attempt. Confirmed working with Martin's stress tester. Reported-By: Martin Liška Signed-Off-By: Frank Ch. Eigler --- debuginfod/ChangeLog | 6 ++++++ debuginfod/debuginfod.cxx | 3 ++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx index a089d0bd..9245be53 100644 --- a/debuginfod/debuginfod.cxx +++ b/debuginfod/debuginfod.cxx @@ -1742,7 +1742,8 @@ handle_buildid_r_match (bool internal_req_p, if ((r == 0) && (fn != b_source1)) // stage 1 continue; - if (fdcache.probe (b_source0, fn)) // skip if already interned + if (fdcache.probe (b_source0, fn) && // skip if already interned + fn != b_source1) // but only if we'd just be prefetching, PR29474 continue; // extract this file to a temporary file -- 2.37.1