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Questions tagged [java]

Programming language and runtime environment that allows compiled Java programs to run unchanged on most hardware and software platforms

1817 questions
146
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3 answers

How can I upgrade to Java 1.8 on an Amazon Linux Server?

I tried sudo yum update but it just keeps java "1.7.0_75". I need 1.8 for it to work with another application but can't figure out how to upgrade it. Do I need to manually install it somehow? There's not much information on this on the internet as…
K_dar
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106
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8 answers

How to determine JAVA_HOME on Debian/Ubuntu?

On Ubuntu it is possible to have multiple JVMs at the same time. The default one is selected with update-alternatives. But this does not set the JAVA_HOME environment variable, due to a debian policy. I am writing a launcher script (bash), which…
Witek
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98
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2 answers

What is .crt and .key files and how to generate them?

I've the following configuration: SSLEngine on SSLCertificateFile /etc/httpd/conf/login.domain.com.crt SSLCertificateKeyFile /etc/httpd/conf/login.domain.com.key SSLCipherSuite ALL:-ADH:+HIGH:+MEDIUM:-LOW:-SSLv2:-EXP but I don't know how to…
Mohammad Ali Akbari
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79
votes
5 answers

Practical maximum open file descriptors (ulimit -n) for a high volume system

We recently began load testing our application and noticed that it ran out of file descriptors after about 24 hours. We are running RHEL 5 on a Dell 1955: CPU: 2 x Dual Core 2.66GHz 4MB 5150 / 1333FSB RAM: 8GB RAM HDD: 2 x 160GB 2.5" SATA Hard…
Kevin
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77
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9 answers

Can't seem to disable Java Automatic Update

I'm just tweaking out my new Windows 7 laptop and wanted to disable the automatic Java updating (and thus kill the silly jusched.exe background process), but I can't seem to get it to actually turn it off. I found the Java Control Panel applet and…
Scott Bussinger
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45
votes
5 answers

How do I install the JRE on a Windows server without Oracle adware?

I would like to install Java on one of our servers, but I am reticent due to Oracle's bundling of an Ask.com toolbar and some virus scanner. I've read that the java updater even installs these for important security fixes if they are missing, and…
Jason Goemaat
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43
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8 answers

What is the value of JAVA_HOME for CentOS?

I have install java through yum on CentOS, however another java programme needs to know what the JAVA_HOME environmental variable is. I know all about setting environmental variables, but what do I set it to? java is installed in /usr/bin/java, it…
Amandasaurus
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36
votes
4 answers

Where to set java heap options (e.g. -Xmx) for Tomcat 6 under Ubuntu 9.04?

I'm running Tomcat using the tomcat6 package from Ubuntu 9.04, which makes a daemon out of Tomcat using jsvc. I'd like to know the proper way to set Java heap options like -Xmx for Tomcat. I'd like to put the configuration wherever is most…
Chris
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33
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2 answers

The option to "Launch slave agents via Java Web Start" is missing from new node configuration, how can I add it to the options menu?

I'm following this official Jenkins guide in order to become familiar with the Jenkins Pipeline configuration. One of the steps there is to create a dumb slave and set it to "Launch slave agents via Java Web Start" but for some reason this option is…
Itai Ganot
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31
votes
8 answers

Is it a Best Industry practice to restart web servers periodically?

We have a web application (developed by a third party) that runs on Tomcat. We have been getting very bad performance from the application. The application developer is claiming that it is an Industry Best Practice to restart web servers every…
Geo
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29
votes
4 answers

Cannot install openjdk-8-jre-headless on Debian Jessie

This Friday I saw that I had 2 held back packages for some reason when I ran apt-get upgrade, so naturally I did what any inexperienced sysadmin would do and uninstalled the packages in the hopes that I could simply re-install them and the problem…
SeinopSys
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21
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6 answers

What consumes memory in java process?

we are trying to investigate memory usage of java process under moderate load. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 12663 test 20 0 8378m 6.0g 4492 S 43 8.4 162:29.95 java As you can see we have resident…
Konstantin S.
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21
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5 answers

How to get a linux network log?

We have a java server running in linux at a specific port that accepts persistent connections for thousands and thousands of users. Recently our clients are not able to connect with a time out error. We suspect the traffic is getting too high but…
erotsppa
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20
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5 answers

I'm designing a system to handle 10000 TCP connections per second, what problems will I run into?

I have a relatively new 8-core box running CentOS. I would like to develop a stats server that uses TCP. It's very simple, it accepts a TCP connection, increments a counter and closes the connection. The catch is it needs to do this at at least 10k…
Larry G
19
votes
5 answers

What is better for a Java Web Application: more CPU cores or a higher clock speed?

I'm not sure whether serverfault is the right place to ask this, but I wonder what choice you would make if you had to select a new CPU type for your Java Web Application: a) a CPU with 32 cores and clock speed 2.5 Ghz or b) a CPU with 8 cores but…
bzero
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