From 63a4aa65ff8eb0498b7a75a820d766e282763d21 Mon Sep 17 00:00:00 2001
From: Jarek Radosz <jradosz@gmail.com>
Date: Mon, 27 Jan 2020 02:59:54 +0100
Subject: [PATCH] DEV: Ignore `ls` errors when clearing FileStore cache (#8780)
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A race condition issue is possible when multiple thread/processes are calling this method.
`ls` prints out to stderr "cannot access '...': No such file or directory" if any of the files it's currently trying to list are being removed by the `xargs rm -rf` in an another process. That doesn't affect the result, but it did raise an error before this change.
Tested on a production instance where the original issue was observed.
Co-Authored-By: Régis Hanol <regis@hanol.fr>
---
lib/file_store/base_store.rb | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/lib/file_store/base_store.rb b/lib/file_store/base_store.rb
index 47c61b60ebe..563970d0880 100644
--- a/lib/file_store/base_store.rb
+++ b/lib/file_store/base_store.rb
@@ -150,14 +150,23 @@ module FileStore
dir = File.dirname(path)
FileUtils.mkdir_p(dir) unless Dir.exist?(dir)
FileUtils.cp(file.path, path)
- # keep latest 500 files
+
+ # Keep latest 500 files
processes = Open3.pipeline(
- "ls -t #{CACHE_DIR}",
+ ["ls -t #{CACHE_DIR}", err: "/dev/null"],
"tail -n +#{CACHE_MAXIMUM_SIZE + 1}",
"awk '$0=\"#{CACHE_DIR}\"$0'",
"xargs rm -f"
)
- raise "Error clearing old cache" if !processes.all?(&:success?)
+
+ ls = processes.shift
+
+ # Exit status `1` in `ls` occurs when e.g. "listing a directory
+ # in which entries are actively being removed or renamed".
+ # It's safe to ignore it here.
+ if ![0, 1].include?(ls.exitstatus) || !processes.all?(&:success?)
+ raise "Error clearing old cache"
+ end
end
private