Child process recurrently being restarted
Stefano Baldo
stefanobaldo at gmail.com
Wed Jun 28 15:20:16 CEST 2017
Hi Guillaume.
I increased the cli_timeout yesterday to 900sec (15min) and it restarted
anyway, which seems to indicate that the thread is really stalled.
This was 1 minute after the last restart:
MAIN.n_object 3908216 . object structs made
SMF.s0.g_alloc 7794510 . Allocations outstanding
I've just changed the I/O Scheduler to noop to see what happens.
One interest thing I've found is about the memory usage.
In the 1st minute of use:
MemTotal: 3865572 kB
MemFree: 120768 kB
MemAvailable: 2300268 kB
1 minute before a restart:
MemTotal: 3865572 kB
MemFree: 82480 kB
MemAvailable: 68316 kB
It seems like the system is possibly running out of memory.
When calling varnishd, I'm specifying only "-s file,..." as storage. I see
in some examples that is common to use "-s file" AND "-s malloc" together.
Should I be passing "-s malloc" as well to somehow try to limit the memory
usage by varnishd?
Best,
Stefano
On Wed, Jun 28, 2017 at 4:12 AM, Guillaume Quintard <
guillaume at varnish-software.com> wrote:
> Sadly, nothing suspicious here, you can still try:
> - bumping the cli_timeout
> - changing your disk scheduler
> - changing the advice option of the file storage
>
> I'm still convinced this is due to Varnish getting stuck waiting for the
> disk because of the file storage fragmentation.
>
> Maybe you could look at SMF.*.g_alloc and compare it to the number of
> objects. Ideally, we would have a 1:1 relation between objects and
> allocations. If that number drops prior to a restart, that would be a good
> clue.
>
>
> --
> Guillaume Quintard
>
> On Tue, Jun 27, 2017 at 11:07 PM, Stefano Baldo <stefanobaldo at gmail.com>
> wrote:
>
>> Hi Guillaume.
>>
>> It keeps restarting.
>> Would you mind taking a quick look in the following VCL file to check if
>> you find anything suspicious?
>>
>> Thank you very much.
>>
>> Best,
>> Stefano
>>
>> vcl 4.0;
>>
>> import std;
>>
>> backend default {
>> .host = "sites-web-server-lb";
>> .port = "80";
>> }
>>
>> include "/etc/varnish/bad_bot_detection.vcl";
>>
>> sub vcl_recv {
>> call bad_bot_detection;
>>
>> if (req.url == "/nocache" || req.url == "/version") {
>> return(pass);
>> }
>>
>> unset req.http.Cookie;
>> if (req.method == "PURGE") {
>> ban("obj.http.x-host == " + req.http.host + " &&
>> obj.http.x-user-agent !~ Googlebot");
>> return(synth(750));
>> }
>>
>> set req.url = regsuball(req.url, "(?<!(http:|https))\/+", "/");
>> }
>>
>> sub vcl_synth {
>> if (resp.status == 750) {
>> set resp.status = 200;
>> synthetic("PURGED => " + req.url);
>> return(deliver);
>> } elsif (resp.status == 501) {
>> set resp.status = 200;
>> set resp.http.Content-Type = "text/html; charset=utf-8";
>> synthetic(std.fileread("/etc/varnish/pages/invalid_domain.html"));
>> return(deliver);
>> }
>> }
>>
>> sub vcl_backend_response {
>> unset beresp.http.Set-Cookie;
>> set beresp.http.x-host = bereq.http.host;
>> set beresp.http.x-user-agent = bereq.http.user-agent;
>>
>> if (bereq.url == "/themes/basic/assets/theme.min.css"
>> || bereq.url == "/api/events/PAGEVIEW"
>> || bereq.url ~ "^\/assets\/img\/") {
>> set beresp.http.Cache-Control = "max-age=0";
>> } else {
>> unset beresp.http.Cache-Control;
>> }
>>
>> if (beresp.status == 200 ||
>> beresp.status == 301 ||
>> beresp.status == 302 ||
>> beresp.status == 404) {
>> if (bereq.url ~ "\&ordenar=aleatorio$") {
>> set beresp.http.X-TTL = "1d";
>> set beresp.ttl = 1d;
>> } else {
>> set beresp.http.X-TTL = "1w";
>> set beresp.ttl = 1w;
>> }
>> }
>>
>> if (bereq.url !~ "\.(jpeg|jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv)$")
>> {
>> set beresp.do_gzip = true;
>> }
>> }
>>
>> sub vcl_pipe {
>> set bereq.http.connection = "close";
>> return (pipe);
>> }
>>
>> sub vcl_deliver {
>> unset resp.http.x-host;
>> unset resp.http.x-user-agent;
>> }
>>
>> sub vcl_backend_error {
>> if (beresp.status == 502 || beresp.status == 503 || beresp.status ==
>> 504) {
>> set beresp.status = 200;
>> set beresp.http.Content-Type = "text/html; charset=utf-8";
>> synthetic(std.fileread("/etc/varnish/pages/maintenance.html"));
>> return (deliver);
>> }
>> }
>>
>> sub vcl_hash {
>> if (req.http.User-Agent ~ "Google Page Speed") {
>> hash_data("Google Page Speed");
>> } elsif (req.http.User-Agent ~ "Googlebot") {
>> hash_data("Googlebot");
>> }
>> }
>>
>> sub vcl_deliver {
>> if (resp.status == 501) {
>> return (synth(resp.status));
>> }
>> if (obj.hits > 0) {
>> set resp.http.X-Cache = "hit";
>> } else {
>> set resp.http.X-Cache = "miss";
>> }
>> }
>>
>>
>> On Mon, Jun 26, 2017 at 3:47 PM, Guillaume Quintard <
>> guillaume at varnish-software.com> wrote:
>>
>>> Nice! It may have been the cause, time will tell.can you report back in
>>> a few days to let us know?
>>> --
>>> Guillaume Quintard
>>>
>>> On Jun 26, 2017 20:21, "Stefano Baldo" <stefanobaldo at gmail.com> wrote:
>>>
>>>> Hi Guillaume.
>>>>
>>>> I think things will start to going better now after changing the bans.
>>>> This is how my last varnishstat looked like moments before a crash
>>>> regarding the bans:
>>>>
>>>> MAIN.bans 41336 . Count of bans
>>>> MAIN.bans_completed 37967 . Number of bans marked
>>>> 'completed'
>>>> MAIN.bans_obj 0 . Number of bans using
>>>> obj.*
>>>> MAIN.bans_req 41335 . Number of bans using
>>>> req.*
>>>> MAIN.bans_added 41336 0.68 Bans added
>>>> MAIN.bans_deleted 0 0.00 Bans deleted
>>>>
>>>> And this is how it looks like now:
>>>>
>>>> MAIN.bans 2 . Count of bans
>>>> MAIN.bans_completed 1 . Number of bans marked
>>>> 'completed'
>>>> MAIN.bans_obj 2 . Number of bans using
>>>> obj.*
>>>> MAIN.bans_req 0 . Number of bans using
>>>> req.*
>>>> MAIN.bans_added 2016 0.69 Bans added
>>>> MAIN.bans_deleted 2014 0.69 Bans deleted
>>>>
>>>> Before the changes, bans were never deleted!
>>>> Now the bans are added and quickly deleted after a minute or even a
>>>> couple of seconds.
>>>>
>>>> May this was the cause of the problem? It seems like varnish was having
>>>> a large number of bans to manage and test against.
>>>> I will let it ride now. Let's see if the problem persists or it's gone!
>>>> :-)
>>>>
>>>> Best,
>>>> Stefano
>>>>
>>>>
>>>> On Mon, Jun 26, 2017 at 3:10 PM, Guillaume Quintard <
>>>> guillaume at varnish-software.com> wrote:
>>>>
>>>>> Looking good!
>>>>>
>>>>> --
>>>>> Guillaume Quintard
>>>>>
>>>>> On Mon, Jun 26, 2017 at 7:06 PM, Stefano Baldo <stefanobaldo at gmail.com
>>>>> > wrote:
>>>>>
>>>>>> Hi Guillaume,
>>>>>>
>>>>>> Can the following be considered "ban lurker friendly"?
>>>>>>
>>>>>> sub vcl_backend_response {
>>>>>> set beresp.http.x-url = bereq.http.host + bereq.url;
>>>>>> set beresp.http.x-user-agent = bereq.http.user-agent;
>>>>>> }
>>>>>>
>>>>>> sub vcl_recv {
>>>>>> if (req.method == "PURGE") {
>>>>>> ban("obj.http.x-url == " + req.http.host + req.url + " &&
>>>>>> obj.http.x-user-agent !~ Googlebot");
>>>>>> return(synth(750));
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> sub vcl_deliver {
>>>>>> unset resp.http.x-url;
>>>>>> unset resp.http.x-user-agent;
>>>>>> }
>>>>>>
>>>>>> Best,
>>>>>> Stefano
>>>>>>
>>>>>>
>>>>>> On Mon, Jun 26, 2017 at 12:43 PM, Guillaume Quintard <
>>>>>> guillaume at varnish-software.com> wrote:
>>>>>>
>>>>>>> Not lurker friendly at all indeed. You'll need to avoid req.*
>>>>>>> expression. Easiest way is to stash the host, user-agent and url in
>>>>>>> beresp.http.* and ban against those (unset them in vcl_deliver).
>>>>>>>
>>>>>>> I don't think you need to expand the VSL at all.
>>>>>>>
>>>>>>> --
>>>>>>> Guillaume Quintard
>>>>>>>
>>>>>>> On Jun 26, 2017 16:51, "Stefano Baldo" <stefanobaldo at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Hi Guillaume.
>>>>>>>
>>>>>>> Thanks for answering.
>>>>>>>
>>>>>>> I'm using a SSD disk. I've changed from ext4 to ext2 to increase
>>>>>>> performance but it stills restarting.
>>>>>>> Also, I checked the I/O performance for the disk and there is no
>>>>>>> signal of overhead.
>>>>>>>
>>>>>>> I've changed the /var/lib/varnish to a tmpfs and increased its 80m
>>>>>>> default size passing "-l 200m,20m" to varnishd and using
>>>>>>> "nodev,nosuid,noatime,size=256M 0 0" for the tmpfs mount. There was
>>>>>>> a problem here. After a couple of hours varnish died and I received a "no
>>>>>>> space left on device" message - deleting the /var/lib/varnish solved the
>>>>>>> problem and varnish was up again, but it's weird because there was free
>>>>>>> memory on the host to be used with the tmpfs directory, so I don't know
>>>>>>> what could have happened. I will try to stop increasing the
>>>>>>> /var/lib/varnish size.
>>>>>>>
>>>>>>> Anyway, I am worried about the bans. You asked me if the bans are
>>>>>>> lurker friedly. Well, I don't think so. My bans are created this way:
>>>>>>>
>>>>>>> ban("req.http.host == " + req.http.host + " && req.url ~ " + req.url
>>>>>>> + " && req.http.User-Agent !~ Googlebot");
>>>>>>>
>>>>>>> Are they lurker friendly? I was taking a quick look and the
>>>>>>> documentation and it looks like they're not.
>>>>>>>
>>>>>>> Best,
>>>>>>> Stefano
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Jun 23, 2017 at 11:30 AM, Guillaume Quintard <
>>>>>>> guillaume at varnish-software.com> wrote:
>>>>>>>
>>>>>>>> Hi Stefano,
>>>>>>>>
>>>>>>>> Let's cover the usual suspects: I/Os. I think here Varnish gets
>>>>>>>> stuck trying to push/pull data and can't make time to reply to the CLI. I'd
>>>>>>>> recommend monitoring the disk activity (bandwidth and iops) to confirm.
>>>>>>>>
>>>>>>>> After some time, the file storage is terrible on a hard drive (SSDs
>>>>>>>> take a bit more time to degrade) because of fragmentation. One solution to
>>>>>>>> help the disks cope is to overprovision themif they're SSDs, and you can
>>>>>>>> try different advices in the file storage definition in the command line
>>>>>>>> (last parameter, after granularity).
>>>>>>>>
>>>>>>>> Is your /var/lib/varnish mount on tmpfs? That could help too.
>>>>>>>>
>>>>>>>> 40K bans is a lot, are they ban-lurker friendly?
>>>>>>>>
>>>>>>>> --
>>>>>>>> Guillaume Quintard
>>>>>>>>
>>>>>>>> On Fri, Jun 23, 2017 at 4:01 PM, Stefano Baldo <
>>>>>>>> stefanobaldo at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Hello.
>>>>>>>>>
>>>>>>>>> I am having a critical problem with Varnish Cache in production
>>>>>>>>> for over a month and any help will be appreciated.
>>>>>>>>> The problem is that Varnish child process is recurrently being
>>>>>>>>> restarted after 10~20h of use, with the following message:
>>>>>>>>>
>>>>>>>>> Jun 23 09:15:13 b858e4a8bd72 varnishd[11816]: Child (11824) not
>>>>>>>>> responding to CLI, killed it.
>>>>>>>>> Jun 23 09:15:13 b858e4a8bd72 varnishd[11816]: Unexpected reply
>>>>>>>>> from ping: 400 CLI communication error
>>>>>>>>> Jun 23 09:15:13 b858e4a8bd72 varnishd[11816]: Child (11824) died
>>>>>>>>> signal=9
>>>>>>>>> Jun 23 09:15:14 b858e4a8bd72 varnishd[11816]: Child cleanup
>>>>>>>>> complete
>>>>>>>>> Jun 23 09:15:14 b858e4a8bd72 varnishd[11816]: Child (24038) Started
>>>>>>>>> Jun 23 09:15:14 b858e4a8bd72 varnishd[11816]: Child (24038) said
>>>>>>>>> Child starts
>>>>>>>>> Jun 23 09:15:14 b858e4a8bd72 varnishd[11816]: Child (24038) said
>>>>>>>>> SMF.s0 mmap'ed 483183820800 bytes of 483183820800
>>>>>>>>>
>>>>>>>>> The following link is the varnishstat output just 1 minute before
>>>>>>>>> a restart:
>>>>>>>>>
>>>>>>>>> https://pastebin.com/g0g5RVTs
>>>>>>>>>
>>>>>>>>> Environment:
>>>>>>>>>
>>>>>>>>> varnish-5.1.2 revision 6ece695
>>>>>>>>> Debian 8.7 - Debian GNU/Linux 8 (3.16.0)
>>>>>>>>> Installed using pre-built package from official repo at
>>>>>>>>> packagecloud.io
>>>>>>>>> CPU 2x2.9 GHz
>>>>>>>>> Mem 3.69 GiB
>>>>>>>>> Running inside a Docker container
>>>>>>>>> NFILES=131072
>>>>>>>>> MEMLOCK=82000
>>>>>>>>>
>>>>>>>>> Additional info:
>>>>>>>>>
>>>>>>>>> - I need to cache a large number of objets and the cache should
>>>>>>>>> last for almost a week, so I have set up a 450G storage space, I don't know
>>>>>>>>> if this is a problem;
>>>>>>>>> - I use ban a lot. There was about 40k bans in the system just
>>>>>>>>> before the last crash. I really don't know if this is too much or may have
>>>>>>>>> anything to do with it;
>>>>>>>>> - No registered CPU spikes (almost always by 30%);
>>>>>>>>> - No panic is reported, the only info I can retrieve is from
>>>>>>>>> syslog;
>>>>>>>>> - During all the time, event moments before the crashes,
>>>>>>>>> everything is okay and requests are being responded very fast.
>>>>>>>>>
>>>>>>>>> Best,
>>>>>>>>> Stefano Baldo
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> varnish-misc mailing list
>>>>>>>>> varnish-misc at varnish-cache.org
>>>>>>>>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>
>
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