[lxc-devel] [PATCH] fix multithreaded create()
S.Çağlar Onur
caglar at 10ur.org
Tue Nov 12 19:35:58 UTC 2013
On Tue, Nov 12, 2013 at 2:04 PM, Dwight Engen <dwight.engen at oracle.com> wrote:
> We were calling save_config() twice within the create() flow, each
> from a different process. Depending on order of scheduling, sometimes
> the data from the first save_config() (which was just the stuff from
> LXC_DEFAULT_CONFIG) would overwrite the config we wanted (the full
> config), causing a truncated config file which would then cause lxc
> to segfault once it read it back in because no rootfs.path was set.
>
> This fixes it by only calling save_config() once in the create()
> flow. A rejected alternative was to call fsync(fileno(fout)) before
> the fclose in save_config.
>
> Signed-off-by: Dwight Engen <dwight.engen at oracle.com>
Great news; This solved the concurrent create problems for me
Bad news; I started to observe destroy() failures (see below)
[caglar at qp:~/go/src/github.com/caglar10ur/lxc/examples] sudo
./concurrent_stress -iteration=100 -count=10
lxc_container: Error destroying rootfs for 5
2013/11/12 14:31:43 [ERROR] ERROR: destroying the
container "5" failed
2013/11/12 14:31:43 [ERROR] ERROR: container "5"
already defined
lxc_container: Error destroying rootfs for 1
2013/11/12 14:32:10 [ERROR] ERROR: destroying the
container "1" failed
2013/11/12 14:32:10 [ERROR] ERROR: container "1"
already defined
lxc_container: Error destroying rootfs for 1
2013/11/12 14:32:25 [ERROR] ERROR: destroying the
container "1" failed
2013/11/12 14:32:25 [ERROR] ERROR: container "1"
already defined
lxc_container: Error destroying rootfs for 7
2013/11/12 14:32:30 [ERROR] ERROR: destroying the
container "7" failed
2013/11/12 14:32:30 [ERROR] ERROR: container "7"
already defined
lxc_container: Error destroying rootfs for 4
2013/11/12 14:33:25 [ERROR] ERROR: destroying the
container "4" failed
2013/11/12 14:33:25 [ERROR] ERROR: container "4"
already defined
lxc_container: Error destroying rootfs for 0
2013/11/12 14:33:40 [ERROR] ERROR: destroying the
container "0" failed
2013/11/12 14:33:40 [ERROR] ERROR: container "0"
already defined
lxc_container: Error destroying rootfs for 0
2013/11/12 14:33:45 [ERROR] ERROR: destroying the
container "0" failed
2013/11/12 14:33:45 [ERROR] ERROR: container "0"
already defined
lxc_container: Error destroying rootfs for 8
2013/11/12 14:33:55 [ERROR] ERROR: destroying the
container "8" failed
2013/11/12 14:33:55 [ERROR] ERROR: container "8"
already defined
lxc_container: Error destroying rootfs for 2
2013/11/12 14:34:40 [ERROR] ERROR: destroying the
container "2" failed
2013/11/12 14:34:40 [ERROR] ERROR: container "2"
already defined
lxc_container: Error destroying rootfs for 1
2013/11/12 14:34:45 [ERROR] ERROR: destroying the
container "1" failed
2013/11/12 14:34:45 [ERROR] ERROR: container "1"
already defined
lxc_container: Error destroying rootfs for 9
2013/11/12 14:35:00 [ERROR] ERROR: destroying the
container "9" failed
2013/11/12 14:35:01 [ERROR] ERROR: container "9"
already defined
[caglar at qp:~/go/src/github.com/caglar10ur/lxc/examples]
but since the original problem is gone now
Acked-by: S.Çağlar Onur <caglar at 10ur.org>
> ---
> src/lxc/lxccontainer.c | 20 ++++++++++++--------
> 1 file changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index c7b2f5e..05ca643 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -1192,16 +1192,19 @@ static bool lxcapi_create(struct lxc_container *c, const char *t,
> if (lxcapi_is_defined(c) && c->lxc_conf && c->lxc_conf->rootfs.path &&
> access(c->lxc_conf->rootfs.path, F_OK) == 0 && tpath) {
> ERROR("Container %s:%s already exists", c->config_path, c->name);
> - free(tpath);
> - return false;
> + goto free_tpath;
> }
>
> - /* Save the loaded configuration to disk */
> - if (!c->save_config(c, NULL)) {
> - ERROR("failed to save starting configuration for %s\n", c->name);
> - goto out;
> + if (!c->lxc_conf) {
> + if (!c->load_config(c, LXC_DEFAULT_CONFIG)) {
> + ERROR("Error loading default configuration file %s\n", LXC_DEFAULT_CONFIG);
> + goto free_tpath;
> + }
> }
>
> + if (!create_container_dir(c))
> + goto free_tpath;
> +
> /*
> * either template or rootfs.path should be set.
> * if both template and rootfs.path are set, template is setup as rootfs.path.
> @@ -1290,10 +1293,11 @@ out_unlock:
> if (partial_fd >= 0)
> remove_partial(c, partial_fd);
> out:
> - if (tpath)
> - free(tpath);
> if (!ret && c)
> lxcapi_destroy(c);
> +free_tpath:
> + if (tpath)
> + free(tpath);
> return ret;
> }
>
> --
> 1.8.3.1
>
>
> ------------------------------------------------------------------------------
> DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps
> OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access
> Free app hosting. Or install the open source package on any LAMP server.
> Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native!
> http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk
> _______________________________________________
> Lxc-devel mailing list
> Lxc-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/lxc-devel
--
S.Çağlar Onur <caglar at 10ur.org>
More information about the lxc-devel
mailing list