From: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>
To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>,
Stefan Reiter <s.reiter@proxmox.com>
Subject: Re: [pbs-devel] [PATCH proxmox-backup 08/11] datastore: add manifest locking
Date: Thu, 15 Oct 2020 09:04:00 +0200 [thread overview]
Message-ID: <1602745233.otfvtzghj8.astroid@nora.none> (raw)
In-Reply-To: <2034541851.106.1602739515152@webmail.proxmox.com>
On October 15, 2020 7:25 am, Dietmar Maurer wrote:
> AFAIR flock with atomically replaced files has problems/races.
>
> Unfortunately, I do not remember why. Somebody remember why? Or is it really safe?
you can obtain the flock a second time after replacing the original
(still locked) file. using a separate lock file that is not touched
other than for flocking solves this problem.
$ flock --verbose testfile -c 'sleep 60'
flock: getting lock took 0.000003 seconds
flock: executing /bin/zsh
while that is running and holding the lock:
$ flock --verbose --wait 5 testfile -c 'sleep 60'
flock: timeout while waiting to get lock
$ mv testfile2 testfile
$ flock --verbose --wait 5 testfile -c 'sleep 60'
flock: getting lock took 0.000003 seconds
flock: executing /bin/zsh
next prev parent reply other threads:[~2020-10-15 7:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 12:16 [pbs-devel] [PATCH 00/11] Locking and rustdoc improvements Stefan Reiter
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 01/11] prune: respect snapshot flock Stefan Reiter
2020-10-15 5:11 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 02/11] prune: never fail, just warn about failed removals Stefan Reiter
2020-10-15 5:12 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 03/11] backup: use shared flock for base snapshot Stefan Reiter
2020-10-15 5:12 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 04/11] reader: acquire shared flock on open snapshot Stefan Reiter
2020-10-15 5:13 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 05/11] verify: acquire shared snapshot flock and skip on error Stefan Reiter
2020-10-15 5:13 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 06/11] gc: avoid race between phase1 and forget/prune Stefan Reiter
2020-10-15 5:17 ` Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 07/11] datastore: remove load_manifest_json Stefan Reiter
2020-10-15 5:28 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 08/11] datastore: add manifest locking Stefan Reiter
2020-10-15 5:25 ` Dietmar Maurer
2020-10-15 7:04 ` Fabian Grünbichler [this message]
2020-10-15 5:39 ` Dietmar Maurer
2020-10-15 7:53 ` Stefan Reiter
2020-10-15 5:43 ` Dietmar Maurer
2020-10-15 7:53 ` Stefan Reiter
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 09/11] datastore: remove individual snapshots before group Stefan Reiter
2020-10-15 5:51 ` [pbs-devel] applied: " Dietmar Maurer
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 10/11] rustdoc: add crate level doc Stefan Reiter
2020-10-14 12:16 ` [pbs-devel] [PATCH proxmox-backup 11/11] rustdoc: overhaul backup rustdoc and add locking table Stefan Reiter
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