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Showing posts with the label JVM

Java parameters for WebLogic Server

There are many burning issues on going WebLogic based environments due to this Java parameters JAVA_OPTIONS, l USER_MEM_ARGS,  PRE_CLASSPATH,  POST_CLASSPATH.  Heap size in MEM The USER_MEM_ARGS can be defined for WebLogic as follows as minimum requirement : -Xms1024m The minimum size of JVM -Xmx1024m The maximum size of JVM keeping the same as minimum will avoid number of GCs. -XX:NewSize=512m The Young Generation (YG) space size -XX:MaxNewSize=512m The maximum sise for Young Generation space -XX:SurvivorRatio=6 There will be two (from, to) survivor spaces both will equal in space and one will be always empty for swapping which will be used after GC. -Xnoclassgc Perm space  -XX:PermSize=128m The permanant space for static classes they will be loaded only once. -XX:MaxPermSize=128m There could be chance of increase of classes as the application functionality increased widely. Troubleshoot OOM errors In production or Development en...

JVM monitoring with jstat Shell Script

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The Oracle WebLogic Server instances are nothing but each one running on a single JVM, when this JVM crashes there could be one of the reasons as overworking of Garbage Collection or not working at all (waiting continuously).   It is good practice that monitoring GC in JVM with detailed statistics will give you a clear idea to analysis at what circumstances happening wrong. And the best way to look in deeper levels of garbage collection also like Young Generation (Eden space, Survivor spaces S0, S1) Old Generation (tenured Generation), and Perm Generation (Statistic Objects/Classes). JDK 1.5 and latest providing excellent JDK command utilities for interrogate the current running Java Process and look inside of JVM take snap with following: 1. jps (Java Process) 2. jstat (JVM status) The 'jps' command with -lv options gives you complete detailed java process arguments for MEM settings and relavent WebLogic Server instances name. We have already discussed about this command ...