Questions tagged [java]
Programming language and runtime environment that allows compiled Java programs to run unchanged on most hardware and software platforms
1,846
questions
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Tomcat ClassNotFoundException after switching from openjdk to sun java
We switched our java version from openjdk jre 1.7 to sun jre 1.7 and now starting tomcat gives the following errors:
SEVERE: Begin event threw error
java.lang.NoClassDefFoundError: org.apache....
5
votes
4
answers
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Glassfish Vs Tomcat (Java app servers)
I am looking at running a java application server on my debian linux webserver, and am looking for a breakdown of the advantages that using either app server would provide me with (or disadvantages). ...
5
votes
5
answers
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Java Deployment Rule Set via AD Enterprise CA
My goal is to get a Java Deployment Rule Set in place in my organization, but I do not want to pay third-party certificate authority for a code signing cert when we have a working CA running through ...
5
votes
5
answers
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How can I monitor memory usage for a windows-based JVM and trigger an alert if it gets too high?
I have an app that runs as a JVM in Windows 2008. I'd like to monitor it's memory usage and be sent an email if/when memory usage reaches a specific threshold. Is there a free utility or method for ...
5
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3
answers
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Setting Java Runtime setting for all users on a client PC
We have a problem with a java application running out of memory. Our (Windows XP) client PCs have JRE 1.6 version 18 installed. I want to increase the -Xmx runtime parameter for the JRE to 512M but I ...
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3
answers
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What port is the Websphere app server's admin app on?
I've started Websphere on my local box and I can't remember what port the admin app should be on. Any ideas?
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4
answers
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How to run IPMI consoles now that NPAPI plugins are no longer supported?
I have a Tyan S5533 motherboard which serves as my NAS drive. It has a dedicated IPMI NIC, but I cannot start up the Java console since Firefox 52, Chrome/Chromium no longer support NPAPI plugins.
I ...
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2
answers
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Does kill -3 actually terminate a java process? Or just generate a thread dump?
CentOS 5.9
If I run kill -3 <java process pid> what actually happens? As per this red hat article, I understand that a Java Thread Dump is generated but is the process terminated? It doesn't ...
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2
answers
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PermGen error in Java, while memory usage seems low
Java application dies from time to time with PermGen space error, but when I look at the
memory usage it seems low from what I can tell.
It is a Tomcat application, plus there is SOLR server running ...
5
votes
4
answers
68k
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Java EE plugin for Eclipse IDE [closed]
I am using Eclipse 3.5.1. There is no option called web-->Dynamic web project. Should I install any plugin for Java EE? If so, please provide me the plugin.
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votes
1
answer
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How to restart java app managed by systemd on OutOfMemory errors
I have the java app (on top of Spring Boot framework) installed as systemd service.
[Unit]
Description=${module_name}-service
Requires=network.target
After=syslog.target
[Service]
User=${user_name}
...
5
votes
2
answers
15k
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Create tomcat war file from static web dir
I created a simple web application that consists of a dir with html, css, js. No server code. For reasons complicated to explain, my administrator insists on turning it into a .war file, so that it ...
5
votes
3
answers
3k
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Tomcat - Spring Framework - MySQL, Load balancing design
Lets say I have Spring Framework App that is running on Tomcat and uses MySQL database:
What would be the best solution in this instance that would allow for sociability (price/performance/...
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5
answers
6k
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Tracing slow Java I/O in Solaris 10
We have a Java application which is significantly slower in Solaris 10 server than in Windows PC.
We have profiled (-Xprof) the application and observed that UnixFileSystem.getBooleanAttributes0 ...
5
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2
answers
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Preserve imported CA Certificates through Java upgrades
I have imported internal Certificate Authorities into Java's CA keystore. (Using keytool to import into the "cacerts" store) This works fine and dandy, until I update the Java RPM. At which point ...
5
votes
1
answer
7k
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OpenJDK or Oracle Java on production server
I'm little bit confused about which implementation is better to use on production server? Are there any reason why not pick OpenJDK?
5
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2
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Stopping Java from showing Update notice to all terminalserver users
on our terminal server all users have minimal (i.e. default) permissions. None are local administrators on that machine.
Still Java Runtime displays message to every user that an update is available. ...
5
votes
2
answers
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Java: Tomcat slow serving static files?
I'm running an instance of Apache Tomcat (5.5) on a Windows 2008 platform. I think I'm seeing an issue related to concurrent file access / locking.
When the number of concurrent HTTP threads is ...
5
votes
3
answers
838
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Scripted install of Sun Java JDK on Ubuntu 9.04
We are trying to script the install of the sun jdk on Ubuntu 9.04 and have it automatically accept the license agreement. I have seen something around the net about creating a file that the package ...
5
votes
3
answers
7k
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JAVA_OPTS -XX:+PrintGCDetails affect on performance?
Does anyone know if the PrintGCDetails affects java performance much? I've been monitoring our java garbage collecting on a staging server with the same setup as the production server.
I assumed ...
5
votes
2
answers
3k
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Can I host my web application in Cloud?
I have made a small web application created in J2EE which i want to develop as a "business".
Can i host it in one of the cloud services ?
Please do advice me as well on this issue. Will the cloud ...
5
votes
1
answer
3k
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MySQL JDBC force ignore client certificate on AWS RDS
I have a Java web app running on AWS and connecting to a MySQL database running on AWS RDS.
My app uses SSL client certificates signed by our own CA to connect to various web services, so I have set ...
5
votes
2
answers
6k
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Using both basic and client-certificate authentication with GlassFish
I'm currently building a Java-servlet applcation (using Jersey on GlassFish to be specific). In some parts of the application I need to authenticate the user using basic authentication and in some ...
5
votes
4
answers
253
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What issues do you need to check for deploying a java application on linux?
What issues should be specifically checked for when deploying a server application written in Java (without any specific platform dependencies) that was written and tested on Windows.
Two that I know ...
5
votes
1
answer
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What does "GC (Allocation Failure)" mean in my ElasticSearch 5.6 logs?
I see these constantly in my Elasticsearch 5.6.3 logs. Is this a signal that I should scale up and add more RAM? Or is this just normal operations for ElasticSearch?
[GC (Allocation Failure) [...
5
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2
answers
5k
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After kill -9 process won't disappear and port is still bound
We have a Java server application running on Mac OS X.
Occasionally this application has become unresponsive, and we have resorted to killing it with kill -9. However, the process doesn't disappear; ...
5
votes
4
answers
4k
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apt-get problem and hang. DPKG was interrupted error afterwards
When I attempt to install a package on my ubuntu(10.10) server on amazon ec2 with update-alternatives" for the JRE, apt-get doesn't respond anymore.
I've been waiting now for 20 minutes on this hang ...
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votes
5
answers
1k
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What configuration changes do you make to a new Tomcat installation?
After installing Tomcat 5 what configuration changes/tweaks do you apply, and why?
Be specific: name what files you edit, what settings you change and why you do it.
Some areas of interest:
General ...
5
votes
1
answer
8k
views
What is the /dev/urandom equivalent on Windows JVM level
Recently, I run into troubles because the lack of entropy and blocking rand IO caused hangs. On Linux, I can do the following:
JAVA_OPTS=-Djava.security.egd=/dev/urandom ./myStartScript.sh
What is ...
5
votes
3
answers
1k
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Virtualbox HTTP load testing, host CPU overload issues
I'm doing HTTP load testing benchmarks (using Apache Benchmark and Siege) on a small Java EE 1.7.0 / Tomcat 7.0.26 application running on a Debian Squeeze 6.0.4 x64 virtualized with Virtualbox 4.1.8. ...
5
votes
1
answer
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Kafka stores log4j logs in directory literally called ${kafka.logs.dir}
I installed a preview version of Kafka 3.0 with log4j2 support (http://home.apache.org/~dongjin/post/apache-kafka-log4j2-support/) on a RHEL 8 server. Kafka and Zookeeper are running successfully as ...
5
votes
2
answers
2k
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Solr Search - java.util.Map$Entry cannot be resolved
I have Solr 3.6.2 running and powering the search for a Magento Enterprise site, and it's all working well, with no errors on startup etc.
However when trying to access the following admin pages:
/...
5
votes
2
answers
770
views
SSH unresponsive after stopping Tomcat, many ksoftirqd CPU usage
I have a weird issue.
Every time I stop Tomcat, SSH becomes very slow, almost totally unresponsive. It takes a minute or even more for SSH to accept any command. When I finally get Tomcat started ...
5
votes
1
answer
3k
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"runas" or "sudo" equivalent on AS400 IBM iSeries
I'm trying to invoke a program to run as another user (by getting input user/pwd) in AS400 OS using Java. Like runas in Windows or sudo in Unix — what can we do in AS400 OS?
I am able to invoke basic ...
5
votes
3
answers
6k
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Java Runtime Environement on Windows 7, disable "Enable the next-generation Java Plug-in"
Starting from jre 1.6u10, browser integration uses a so-called "next-generation plugin".
Some old applications are not compatible with it, and (on windows) it could be disabled in control panel, ...
5
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3
answers
2k
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What are the best practices for monitoring and alerting for low level JVM metrics?
I'm looking to set up monitoring and alerting for java server based app and want to find some best practices for monitoring JVM specific metrics and for designing alerts based on those metrics.
So ...
5
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2
answers
4k
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Why does the Java VM process eat up more RAM then specified in -Xmx parameter?
I have multiple servers running CentOS 5.4 and only one application running on Java VM. I've configured the Java VM with the following arguments:
java -Xmx4500M -server -XX:+UseConcMarkSweepGC -XX:+...
5
votes
1
answer
2k
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Mysql, SSL and java client problem
I'm trying to connect to an SSL-enabled mysql server from my own java application. After setting up ssl on mysqld, and successfuly tested an account using "REQUIRE ISSUER and SUBJECT", I wanted to use ...
5
votes
1
answer
972
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How do companies handle the need for different Java requirements on the same user?
In our company, we use GPOs to push software updates such as Java updates. We have about 150 users in different offices located in different countries, all using Windows 7. We have a few office-...
5
votes
1
answer
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How to install Oracle Java on Debian Wheezy with make-jpkg and fakeroot without errors?
How to install Oracle Java on Debian Wheezy with make-jpkg and fakeroot?
the manual for installing oracle java on debian wheezy is quite clear and understandable:
http://wiki.debian.org/JavaPackage
...
5
votes
1
answer
2k
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Automatic updating of newer JRE on GNU/Linux
How can a GNU/Linux machine be set up to automatically update a newer version of the Java Runtime Environment (JRE)? The difficulty is wanting to use a newer version of Java (Java 7, at present) and ...
5
votes
2
answers
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Tomcat directly serve static (css, js) files shared by multiple applications
I'm using the ExtJS framework which has a bulk of js and css files that are used for all apps. I intend to share these between a number of web applications (different war files).
For this reason I ...
4
votes
4
answers
9k
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What is a Servlet Container and how to install one?
I am about to order a VPS (virtual private server) from a provider, and I guess I have to install some Servlet Container right?
I am about to use SOLR and my website is PHP MYSQL JAVASCRIPT based.
...
4
votes
3
answers
349
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MultiCPU servers - which one can you suggest? [closed]
We want to install a couple of big servers for our customer to run Oracle on one and Java applications on another. Tired with clusters, replications, want to run everything on one big server.
We ...
4
votes
5
answers
6k
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How to diagnose RAM?
I have a java process that is aborted after a while with SIGSEGV. It started to happen after I upgraded the server with more RAM. Having tested on different JVMs I suspect it might be a hardware ...
4
votes
2
answers
7k
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Why is Wireshark not capturing certain POST requests?
If I use this filter in Wireshark: http.request.method == "POST" and use the vote buttons to vote for a stack exchange question, then Wireshark captures the corresponding POST request. I can also see ...
4
votes
7
answers
361
views
What platform do you run your java apps on?
Even though the JVM is cross-platform, there are be differences in
behaviour;
performance;
stability.
Some of them are quite clear, as in the heap size limitation on 32bit. Some of them are not, ...
4
votes
3
answers
625
views
Java default JRE parameters on Unix
Is it possible to configure java in unix to always add a JRE parameter whenever java is run?
e.g. -Dcom.sun.management.jmxremote.port=25800
4
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3
answers
419
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Why shouldn't I serve my Java webapp directly with Tomcat?
I have heard several times that one should not serve a Java webapp directly to the outside world from the Tomcat server it is running on. Rather, one should have a regular web server in between -- e....
4
votes
1
answer
2k
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How the big guys monitor their servers?
I'm wondering what software the web scale guys are using to monitor their n arrays of servers in the server farm(s).
What does facebook, twitter, digg use? How google does it?
I'm looking for a ...