Resource temporarily unavailable

If you see a message like following while working on centos system, that means the particular user you are using has exceeded the open process limit.


bash: fork: retry: Resource temporarily unavailable
bash: fork: retry: Resource temporarily unavailable
bash: fork: retry: Resource temporarily unavailable
bash: fork: retry: Resource temporarily unavailable


So you need to increase it. Here is the way...

Login as root. Go to "limits.conf" file.

> vi /etc/security/limits.conf

Set a higher number of "nproc" value.
Add these two lines.

user          soft    nproc     65550
user          hard    nproc     65555

user - replace with your username

source : https://access.redhat.com/solutions/30316

Get "pretty" result always without typing .pretty() on mongo.

When executing mongo commands we put .pretty() at the end to get a readable out put.

Ex:

db.myTable.find({"id":"123"}).pretty()

However there is a way to avoid this command. Just enter the following line into "$HOME/.mongorc.js"

DBQuery.prototype._prettyShell = true

That will enable pretty print globally by default.

Check Java application Memory consumption using jconsole

First add these JAVA OPTS to the application.

JAVA_OPTS="$JAVA_OPTS -Djava.rmi.server.hostname="
JAVA_OPTS="$JAVA_OPTS -Djava.rmi.server.useLocalHostname"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.port=9010"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.local.only=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.ssl=false"

Or to the wrapper.xml

wrapper.java.additional.14=-Djava.rmi.server.hostname=
wrapper.java.additional.15=-Djava.rmi.server.useLocalHostname
wrapper.java.additional.16=-Dcom.sun.management.jmxremote
wrapper.java.additional.17=-Dcom.sun.management.jmxremote.port=9010
wrapper.java.additional.18=-Dcom.sun.management.jmxremote.local.only=false
wrapper.java.additional.19=-Dcom.sun.management.jmxremote.authenticate=false
wrapper.java.additional.20=-Dcom.sun.management.jmxremote.ssl=false


Then start the java application.

Start jconsole. The java path should have setted.

> jconsole

Go to "Connection --> New connection".
Select "Remote" tab and give the IP and port, Click connect.
Go to "Memory" tab.