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From "Chou, Peter" <pbc...@labs.att.com>
Subject RE: Ramdisk - 6.2.1 vs 7.0.0
Date Fri, 16 Jun 2017 18:13:25 GMT
Bryan,

Turns out that this memory leak is the result of configuring a log collation host in “logs_xml.config”
and then having the host be down during the traffic run. We verified that this occurs with
vanilla 6.2.1. We also noticed that there was a memory leak fix in this function patched in
TS-4872, which is present in 6.2.x, 7.1.x, and master. So we tried the latest 6.2.x (current)
from yesterday, but the memory leak still occurred. We have also seen that bringing up the
log host during the test run stabilizes the memory allocation so we’re pretty sure that
this is the trigger for the memory leak.

Some heap-check output from ATS compiled with tcmalloc --
Total: 3014.2 MB
  2902.3  96.3%  96.3%   2902.3  96.3% ats_malloc
    76.0   2.5%  98.8%     76.0   2.5% ats_memalign
    35.8   1.2% 100.0%   2938.1  97.5% LogObject::_checkout_write
     0.1   0.0% 100.0%      0.1   0.0% BaseLogFile::open_file
     0.0   0.0% 100.0%      0.0   0.0% ResourceTracker::lookup (inline)

Thanks,
Peter


From: Bryan Call [mailto:bcall@apache.org]
Sent: Saturday, June 10, 2017 8:12 AM
To: users@trafficserver.apache.org
Subject: Re: Ramdisk - 6.2.1 vs 7.0.0

Do you have TLS connections? (https).  You can use tcmalloc or jemalloc to profile the memory
allocation.

-Bryan

On Jun 9, 2017, at 11:50 AM, Chou, Peter <pbchou@labs.att.com<mailto:pbchou@labs.att.com>>
wrote:

Bryan,

Our default_inactivity_timeout is set to 300s. We have looked at the memory dump in traffic.out
as well, but we’re stumped because the memory that is tracked in the dump only comes out
to about 8GB and 6GB total allocated and used respectively while pmap -x <pid> reports
around 26GB memory allocated to the process.

From pmap -- 26127468 11646528 11646094    8773892  11644512 12341772 == [ size rss pss referenced
anonymous swap ] (KB)
From traffic.out -- 7895071920 |         5956998576 |            | TOTAL (B)

Is this similar to run-away anon region allocation seen before? Appreciate any insights.

Thanks,
Peter


From: Bryan Call [mailto:bcall@apache.org]
Sent: Friday, June 09, 2017 9:02 AM
To: users@trafficserver.apache.org<mailto:users@trafficserver.apache.org>
Subject: Re: Ramdisk - 6.2.1 vs 7.0.0

What is your proxy.config.net.default_inactivity_timeout set to?  You can also do a dump of
the memory by doing:

$ sudo kill -SIGUSR1 $(pidof traffic_server). # and look at traffic.out.

That will give a pretty good idea on where the memory is being used.

-Bryan

On Jun 8, 2017, at 3:35 PM, Jeremy Payne <jp557198@gmail.com<mailto:jp557198@gmail.com>>
wrote:

ATS versions - 6.2.1
Cache disk - 18G ramdisk - /dev/ram0
Storage.config configured to use 14G of ramdisk
System memory - 32G
Traffic type - HLS Live
Connections - sustained 4k
Trafffic - 5-6gbps
Hit ratio - 97%

So it looks like I misread/misinterpreted a few things during testing referenced in my previous
email.
It looks like my issue was never run away memory using ramdisk,
it looks like something internal to ATS that I can't seem to isolate.

Since I am not seeing this type of memory consumption with my large-file/VOD cache servers,
and the connection profile is much different, I am guessing what may be at issue is the long
living
connections. ATS active timeout is currently set to 3600. This is live traffic so connections
stay open for a hour
and then closed.  Where as with my large-file/VOD cache servers, connections only remain
open for as long as a file/title is being retrieved. 10-15mins max.

Has anyone seen any issues with this type of connection profile and ATS 6.2.1?

This doesnt seem to be an issue with 7.0, so not sure what may have changed between releases.

Thanks!



On Tue, Jun 6, 2017 at 8:32 AM, Jeremy Payne <jp557198@gmail.com<mailto:jp557198@gmail.com>>
wrote:
ATS versions - 6.2.1 and 7.0.0
Cache disk - 18G ramdisk - /dev/ram0
System memory - 32G
Traffic type - HLS Live

While testing live HLS traffic, I noticed that ATS 6.2.1. continued to use ramdisk until
eventually traffic_server was restarted(via trafic_cop) as result of 'oom killer'

Testing with ATS 7.0.0 I saw memory use remain stable once the ramdisk reached it's
'configured' capacity.

I looked through the 7.0 changelog and didnt see anything obvious, so maybe someone is aware
of an undocumented change which impacts ATS 'honoring' configured  ramdisk boundaries.
Understood ATS may not know the difference between /dev/sdX and /dev/ramX.. But just
putting this out to the community just in case I am missing something.

Jeremy

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