On 08.08.2019 20:08, Eric Robinson wrote:
Utkarsh and John, thank you for your feedback.
Since everything was originally on Windows, and we built a new Linux server
with fresh tomcat installs, and the only thing we moved over from the old
Windows servers was the tomcat application folder itself, and the 100% CPU
problem persisted, I can't imagine what else could be causing it except the
tomcats, but I'm open to ideas.
When it happens, all the tomcats start using high CPU at the same time. See the
following top output.
top - 11:06:44 up 1 day, 6:59, 7 users, load average: 36.85, 32.67, 34.89
Tasks: 245 total, 4 running, 241 sleeping, 0 stopped, 0 zombie
%Cpu(s): 80.7 us, 13.5 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 5.7 si, 0.0 st
KiB Mem : 48132572 total, 11677420 free, 5572688 used, 30882464 buff/cache
KiB Swap: 15626236 total, 15584324 free, 41912 used. 41859232 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
19379 site211 20 0 3529072 447444 24632 S 120.4 0.9 3:37.19 java
20092 site555 20 0 2530376 375500 24496 S 72.4 0.8 2:01.44 java
21077 site450 20 0 2530292 298260 24292 S 69.6 0.6 1:10.92 java
20378 site436 20 0 3262200 347160 24096 S 68.3 0.7 2:47.26 java
19957 site522 20 0 2596856 373532 24364 S 52.0 0.8 2:37.13 java
19537 site396 20 0 2862724 386860 23820 S 51.1 0.8 2:34.25 java
19228 site116 20 0 3595652 490032 24640 S 50.5 1.0 5:03.28 java
20941 site456 20 0 2596996 338740 24488 S 49.2 0.7 1:32.89 java
20789 site354 20 0 2596920 327612 24480 S 42.9 0.7 1:30.47 java
20657 site327 20 0 3123004 346308 24540 S 41.4 0.7 1:50.97 java
20524 site203 20 0 2458376 340400 25416 S 39.8 0.7 1:48.01 java
19675 site487 20 0 2530296 390948 24408 S 35.7 0.8 2:37.95 java
20233 site535 20 0 2530292 324112 24360 S 32.9 0.7 1:54.31 java
19809 site514 20 0 2530216 400308 24340 S 25.7 0.8 2:35.97 java
44 root 20 0 0 0 0 R 19.1 0.0 159:46.15 ksoftirqd/7
3926 root 20 0 208512 22668 4128 S 16.9 0.0 242:45.07 iotop
2036 root 20 0 0 0 0 R 13.2 0.0 1:38.31 kworker/7:0
I'll check the localhost_access logs and see if something suspicious stands out.
Access logs is the first thing to look at of course (just in case you are
subject to some
DoS attack), but other things of interest :
1) what is "the webapp" in question ? Any reason to suspect it may have been been
hijacked, to do something it is not supposed to do ? does the webapp allow for clients to
upload "things" to the server (files, documents, images,..) ?
2) if you look at the tomcat logs, do you recognise all the webapps which get deployed
when tomcat starts ? Or is there an alien there ?
3) if you run "top" again, then enter a "c" in the console, it will show more details
about the "java" command it is running.
Similarly, doing a "ps -ef" command and comparing the result (by PID) with the top output,
may give more details.
That would show (us) at least the startup parameters of your tomcat(s).
4) speaking as a faithful Tomcat Committer, we always like to repeat that in 99% of the
cases it turns out that the problem is with the webapp, not with Tomcat. The fact that in
your case, you have changed about everything except the webapp, and the problem persists,
would only tend to increase that suspicion..
So, can the webapp do any logging that would show what it's doing, while it is happily
slurping all your CPU time ?
6) does the tomcat error log show anything of interest ?
7) under Linux as root, enter : netstat --tcp -pan | grep LISTEN
(Shows all TCP ports your server is listening to, and which PID/processes control these
ports).
Anything unexpected there ? worse : anything unexpected which would match the PID of one
of your tomcats ?
André
--Eric
-----Original Message-----
From: Utkarsh Dave <utkarshkd...@gmail.com>
Sent: Thursday, August 8, 2019 12:33 PM
To: Tomcat Users List <users@tomcat.apache.org>
Subject: Re: Tomcat Server Using 100% CPU
Did you reviewed the localhost_access log file. Which web-application is using
tomcat the most ?
On Thu, Aug 8, 2019 at 9:53 AM Eric Robinson <eric.robin...@psmnv.com>
wrote:
We have a farm of VMs, each running multiple instances of tomcat (up
to 80 instances per server). Everything has been running fine for
years, but recently one server has started nailing the CPU to 100% utilization.
We have tried:
* Different versions of tomcat and JDK
* Doubling the resources to 16 cores and 56 GB RAM
* Moving the VM to different physical server
* Rebuilding the tomcat instances on a brand new VM using Windows
Server 2019
* Rebuilding the tomcat instances on a brand new VM using Red Hat
Enterprise Linux 7.5
Nothing has worked. No matter where we run the tomcats, they drive CPU
up to 100%. Meanwhile the other six servers are still running fine.
They all run the same canned tomcat applications.
We would appreciate some guidance on getting to the bottom of this problem.
--Eric
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