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We are running an Amazon EC2 R3 instance so has 30G of memory available. We are running 5 Apache Tomcats (version 7). According to lsb_release -a the version of Ubuntu is: Ubuntu 14.04.2 LTS

Tomcats keep terminating on this machine from unknown conditions. This machine is more than adequate to run many Tomcats and after a single Tomcat termination, running free -h shows at least 10G available.

When I run the command cat/proc/swaps the following is displayed:

cat /proc/swaps
Filename                                Type            Size    Used    Priority

Does this mean that no swap partition is in place? Running the swapon command shows the same output:

swapon -s
Filename                                Type            Size    Used    Priority

Running the top command shows:

Swap:        0 total,        0 used,        0 free.

So do these results show that no swap is available for when processes need it or does it show no swap is currently being used?

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2 Answers 2

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As long as there is free memory available, the system will never use swap. In fact, swapping should be avoided in a system as possible...

On the other hand, in your case, it seems that you don't have a swap partition. Otherwise you should see something like this:

$ swapon -s 
Filename                Type        Size    Used    Priority
/dev/sdb1                               partition   1952764 0   -1
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  • Agree about avoiding swapping, but I am trying to determine why the "watchdog" is terminating my Tomcats (assuming that is what is happening). So does the output above show that I have no swap space allocated or no swap space is being used or do I need to run another process to find out my swap size?
    – Phil
    Jul 9, 2015 at 12:31
  • Try sudo fdisk -l to see your partitions
    – Daniel Lopez
    Jul 9, 2015 at 12:35
  • This results in: Device Boot Start End Blocks Id System /dev/xvda1 * 16065 16771859 8377897+ 83 Linux so this indicates no swap partition. Thank you for clearing that up.
    – Phil
    Jul 9, 2015 at 12:51
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If I were You , I'd use multiple smaller EC2 Instances (t2 mini-micro) each for dedicated tomcat with dedicated hostings usin an EBL( Elastic Load Balancer) & ASG (auto scaling groups). It will give a more robust package as far as multiple apache are under consideration and will be more cost efficient.

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