Henrik,

uh, okay. I suppose it worked for you in 0.92 as well?

I will create an issue on GitHub for that.

Bernd

On 25 February 2015 at 17:14, Henrik Johansen <[email protected]> wrote:
> Bernd,
>
> We saw the exact same issue - here is a graph over the CPU idle
> percentage across a few of the cluster nodes during the upgrade :
>
> http://5.9.37.177/graylog_cluster_cpu_idle.png
>
> We went from ~20% CPU utilisation to ~100% CPU utilisation across
> ~200 cores and things only settled down after disabling force_rdns.
>
>
> On 25 Feb 2015, at 11:55, Bernd Ahlers <[email protected]> wrote:
>
> Johan,
>
> the only thing that changed from 0.92 to 1.0 is that the DNS lookup is
> now done when the messages are read from the journal and not in the
> input path where the messages are received. Otherwise, nothing has
> changed in that regard.
>
> We do not do any manual caching of the DNS lookups, but the JVM caches
> them by default. Check
> http://docs.oracle.com/javase/7/docs/technotes/guides/net/properties.html
> for networkaddress.cache.ttl and networkaddress.cache.negative.ttl.
>
> Regards,
> Bernd
>
> On 25 February 2015 at 08:56,  <[email protected]> wrote:
>
> This is strange, I went through all of the settings for my reply, and we are
> indeed using rdns, and it seems to be the culprit. The strangeness is that
> it works fine on the old servers even though they're on the same networks,
> and using the same DNS's and resolver settings.
> Did something regarding reverse DNS change between 0.92 and 1.0? I'm
> thinking perhaps the server is trying to do one lookup per message instead
> of caching reverse lookups, seeing as the latter would result in very little
> DNS traffic since most of the logs will be coming from a small number of
> hosts.
>
> Regards
> Johan
>
> On Tuesday, February 24, 2015 at 5:08:54 PM UTC+1, Bernd Ahlers wrote:
>
>
> Johan,
>
> this sounds very strange indeed. Can you provide us with some more
> details?
>
> - What kind of messages are you pouring into Graylog via UDP? (GELF,
> raw, syslog?)
> - Do you have any extractors or grok filters running for the messages
> coming in via UDP?
> - Any other differences between the TCP and UDP messages?
> - Can you show us your input configuration?
> - Are you using reverse DNS lookups?
>
> Thank you!
>
> Regards,
> Bernd
>
> On 24 February 2015 at 16:45,  <[email protected]> wrote:
>
> Well that could be a suspect if it wasn't for the fact that the old
> nodes
> running on old hardware handle it just fine, along with the fact that
> the
> traffic seems to reach the nodes just fine(i.e it actually fills the
> journal
> up just fine, and the input buffer never breaks a sweat). And it's
> really
> not that much traffic, even spread across four nodes those ~1000
> messages
> per second will cause this whereas the old nodes are just two and can
> handle
> it just fine.
>
> About disk tuning, I haven't done much of that, and I realize I forgot
> to
> mention that the Elasticsearch cluster is on separate physical hardware
> so
> there's a minuscule amount of disk I/O happening on the Graylog nodes.
>
> It's really very strange since it seems like UDP itself isn't to blame,
> after all the messages get into Graylog just fine and fills up the
> journal
> rapidly. The screenshot from I linked was from after I had stopped
> sending
> logs, i.e there was no longer any ingress traffic so the Graylog process
> had
> nothing to do except emptying it's journal so it should all be internal
> processing and egress traffic to Elasticsearch. And as can be seen in
> the
> screenshot it seems like it's doing it in small bursts.
>
> In the exact same scenario(i.e when I just streamed a large file into
> the
> system as fast as it could receive it) but with the logs having come
> over
> TCP, it'll still store up a sizable number of messages in the journal,
> but
> the processing of the journaled messages is both more even and vastly
> faster.
>
> So in short it doesn't appear to be the communication itself, but
> something
> happening "inside" the Graylog process, but that only happens when the
> messages have been delivered over UDP.
>
> Regards
> Johan
>
>
> On Tuesday, February 24, 2015 at 3:07:47 PM UTC+1, Henrik Johansen
> wrote:
>
>
> Could this simply be because TCP avoids (or tries to avoid) congestion
> while UDP does not?
>
> /HJ
>
> On 24 Feb 2015, at 13:50, [email protected] wrote:
>
> Hello,
>
> With the release of 1.0 we've started moving towards a new cluster of
> GL
> hosts. These are working very well, with one exception.
> For some reason any reasonably significant UDP traffic will choke the
> message processor, fill up and process buffers on all four hosts, and
> effectively choke up all other message processing as well.
> Normally we do around 2k messages per second, split roughly 50/50
> between
> TCP and UDP. Sending the entire TCP load to one host doesn't present a
> problem, it doesn't break a sweat.
>
> I've also experimented a little with sending a large text file using
> rsyslog's imfile module, sending it via TCP will bottleneck us at the
> ES
> side of things and cause the disk journal fill up fairly rapidly, but
> it's
> still working at at ~9k messages per second so that's fine. Sending it
> via
> UDP just causes GL to choke again, fill up the journal to a certain
> point
> and slowly slowly process the journal at little bursts of a few
> thousand
> messages followed by several seconds of apparent sleeping(i.e pretty
> much no
> CPU usage).
>
> During all of this the input buffer never fills up more than at most
> single digit percentages, using TCP the output buffer sometimes moves
> up to
> 20-30%, with UDP it never moves at all. It's all in the process buffer.
> Sending a large burst of messages and then stopping doesn't seem to
> affect
> this behavior either, even after the inbound messages stop it still
> takes a
> long time to process the messages that are already in the journal and
> process buffer.
> I'm using VisualVM to look at the CPU and memory usage, this is a
> screenshot of a UDP session:
> http://i59.tinypic.com/x23xfl.png
>
> I've tried mucking around with various knobs, processbuffer_processors,
> JVM settings, etc, with no results whatsoever, good or bad.
> There's nothing to suggest a problem in neither the graylog nor system
> logs.
>
> Pertinent specs and settings:
> ring_size = 16384 (CPU's have 20 MB L3)
> processbuffer_processors = 5
>
> Java 8u31
> Using G1GC with StringDeduplication, I've tried without the latter and
> just using CMC as well, no difference.
> 4 GB Xmx/Xms.
> Linux 3.16.0
> net.core.rmem_max = 8388608
>
> These are virtual machines, VMware, 8 GB / 8 vCPU's, Xeon E5-2690's.
>
> Software wise the old nodes are running the same setup more or less,
> except kernel 3.2.0, same JVM, G1GC, etc. Hardware wise, they're
> physical
> boxes, old Dell 2950's with dual quad core E5440's. That's Core2 era so
> quite a bit slower.
>
> Any ideas?
>
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> Fax.: +49 (0)40 609 452 078
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> Steckelhörn 11
> 20457 Hamburg
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>
> Commercial Reg. (Registergericht): Amtsgericht Hamburg, HRB 125175
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Fax.: +49 (0)40 609 452 078

TORCH GmbH - A Graylog company
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Germany

Commercial Reg. (Registergericht): Amtsgericht Hamburg, HRB 125175
Geschäftsführer: Lennart Koopmann (CEO)

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