I’ve got tomcat 8.5.9 installed on a CentOS 7.2 droplet. When I restart tomcat, with only the tomcat manager in the webapps directory, restarts take anywhere from 3 to 15 minutes, and sometimes even longer. Has anyone seen such behavior? Top doesn’t show much CPU or memory being consumed by Java. We’re running OpenJDK 1.8.0_111. Normal restart times with no webapps is a couple of seconds on other systems.
This textbox defaults to using Markdown to format your answer.
You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!
Accepted Answer
Slow start up times for Tomcat are often related to Java’s SecureRandom implementation. By default, it uses /dev/random as an entropy source. This can be slow as it uses system events to gather entropy (e.g. disk reads, key presses, etc). As the urandom manpage states:
When the entropy pool is empty, reads from
/dev/randomwill block until additional environmental noise is gathered.
One work around is to use /dev/urandom instead as it does not block. This is defined in your JAVA_OPTS That can be set in a number of places depending on how you set up Tomcat in the first place. It will usually be the init script or systemd service file used to start Tomcat.
-Djava.security.egd=file:/dev/./urandom
See this tutorial for more information.
Another option is to use haveged to generate more entropy. On CentOS, you can do so with:
yum install haveged
systemctl start haveged
systemctl enable haveged
For more information on how haveged works, check out this tutorial:
Become a contributor for community
Get paid to write technical tutorials and select a tech-focused charity to receive a matching donation.
DigitalOcean Documentation
Full documentation for every DigitalOcean product.
Resources for startups and SMBs
The Wave has everything you need to know about building a business, from raising funding to marketing your product.
The developer cloud
Scale up as you grow — whether you're running one virtual machine or ten thousand.
Get started for free
Sign up and get $200 in credit for your first 60 days with DigitalOcean.*
*This promotional offer applies to new accounts only.