Primary Note on Oracle WebLogic Server Core Server and Performance Issues Support Patterns (Doc ID 760172.1)

Last updated on MAY 19, 2021

Applies to:

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Troubleshooting Core Server and Performance Issues

• Binary Core File Analysis - An application gets a binary core file produced when the WebLogic Server process terminates due to some invalid native core (machine specific code). A server crash, JVM crash, machine crash, or HotSpot error may also be associated with this occurrence. This pattern will describe what steps are needed to gather information from a core file on various platforms. <Note 779344.1>
  
  
• Unexpected High CPU Usage with WLS - A system administrator or user notices that the WebLogic Server process is consuming a lot of CPU cycles and wants to know why/what is consuming CPU cycles. <Note 779349.1>
  
  
• Too Many Open Files - A system error "Too many open files" is reported in the WebLogic Server log. Users may see this as either java.net.SocketException: Too many open files OR java.io.IOException: Too many open files. For details on this, refer to <Note 867492.1>
  
  
• Generic Server Hang - A server hang is suspected when the server does not respond to new requests, requests time out, requests take longer to process, or may occur after a server crash. <Note 1264286.1>
  
  • EJB_RMI Server Hang - Unnecessary network traffic is causing threads to wait for responses to outstanding rmi/rjvm requests. These requests are a result of remote JNDI lookups in a clustered domain. <Note 1134285.1>
  • ServerHang - Application Deadlock - An inadvertent deadlock in the application code can cause a server to hang. For example, a situation in which thread1 is waiting for resource1 and is holding a lock on resource2, while thread2 needs resource2 and is holding the lock on resource1. Neither thread can progress. <Note 1264876.1>
  • JDBC Causes Server Hang - There can be different possible reasons for JDBC calls to lead to a hanging WLS instance, such as use of DriverManager.getConnection() in JDBC code, long running SQL Queries, hanging database, slow network, application-level deadlock, problems with RefreshMinutes or TestFrequencySeconds settings, and pool shrinking. This pattern addresses troubleshooting for these common problems. <Note 1135278.1>
    
    
• Investigating Missing Execute Threads - The missing threads issue is discovered during analysis of a server hang problem or unexplained timeouts or other confusing and unexplained behavior. In a default WebLogic Server configuration, there should be 15 execute threads for the default queue (0 through 14). But in some situations, a thread dump shows that some execute threads are missing from the "default" queue. There is no exception, stack trace, or notification of any kind in the server log indicating that threads have died. <Note 1333514.1>
  
  
• Investigating Out of Memory / Memory Leak Problems - An application displays Out of Memory errors due to memory exhaustion, either in java heap or native memory. <Note 877172.1>
  
  
• Investigating JVM Crashing with No Core Dump - A JVM is an ordinary process like any other, and can sometimes terminate unexpectedly. A core dump (a memory map of the running process) is usually created when a process crashes. Sometimes, however, a core dump is not created. This pattern addresses some reasons for a missing core dump and actions to take to correct the situation and troubleshoot the problem. <Note 1276688.1>
  
  
• Investigating ClassCastExceptions - A ClassCastException is a runtime exception raised by the JVM when it detects an incompatible cast between two types. Such an error generally terminates the user request. This pattern attempts to give some basic elements to understand and troubleshoot the most frequent causes of ClassCastException errors. <Note 1331181.1>

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