Welcome!

Weblogic Authors: Elizabeth White, Michael Meiner, Michael Bushong, Avi Rosenthal

Related Topics: Weblogic

Weblogic: Article

Handling System Core Files

Before you debug

This article will provide some useful tips for debugging your BEA WebLogic Server applications when a system core file occurs. It describes debugging tips, problem troubleshooting, and tools available to assist you in this process.

A system core file is usually indicative of an error in some native code. This could be from the application code of a user (if you are using native code [JNI] in your application), an error in the Java Virtual Machine version you are using, or in BEA WebLogic Server itself. There are a couple of places where native code could have caused the system core file to happen on your operating system. The following ideas and suggestions will help narrow the problem and stabilize the application until the exact cause of the system core can be determined.

The Java Virtual Machine
The first place to look is at the JVM itself. The JVM is a native program and can cause such errors. When in doubt, you can try another certified JVM and/or a later release to determine if a JVM bug is at fault. Many JVM bugs involve the use of the JIT compiler and disabling this feature will often resolve this type of problem. This can be done by supplying the "-Djava.compiler=none" option to the Java command line. Most of the time the JVM will produce a small log file that may contain useful information as to which library the system core may have come from; however, this is not true all of the time. The file is produced in the directory where BEA WebLogic Server was started and is of the form "hs_err_pid<PID #>.log", where "<PID #>" is the process ID of the BEA WebLogic Server process. On AIX this file would be "javacore<PID>.<ID Number>.txt", where "<PID #>" is the process ID of the BEA WebLogic Server process and "<ID Number>" is a number generated by the operating system. You can go to http://java.sun.com and search the Bug Database with the HotSpot "Error ID" number or the method that was happening when the error was reported.

Native Code
The next place to look is at any native libraries that are accessed with JNI (native code) calls in your application, if applicable. This can also cause a system core file to be produced. If your application uses such libraries, they should be carefully examined. It may be difficult to rule out these libraries, as their functionality may not be easily removed from the application. Extensive logging may be needed to determine if a pattern of use can be correlated with the system core dump/Dr. Watson error.

Another place is any Type 2 JDBC driver that makes use of native DBMS libraries, which could also produce this type of error. An option is to switch to a pure Java (Type 4) JDBC driver in order to determine if that is the cause. You can also check with the Type 2 JDBC driver provider to see if there are any known issues or if there is an updated version of the native libraries available.

A final place that could have caused this could be in the BEA WebLogic Server performance pack. This is also native code and when enabled could potentially produce such an error. One option is to disable this feature to determine if that is the cause. This can be done by adding "-Dweblogic.NativeIOEnabled=false" to the command line to start your server. If you are on an older service-pack version you can also check the list of fixed change requests for your particular BEA WebLogic Server version at http://edocs.bea.com.

System Core File
If after looking at the above items you cannot determine the cause of the error, then we can examine the system core file that was produced. If a system core file is produced it will be in the directory where BEA WebLogic Server was started. You will need to run an operating system-specific debugger on the resulting system core file to get a stacktrace that may help in pointing to the offending code.

If you are in development and the system core consistently happens, you can set the following flags to allow a thread dump to be taken of the server right before a core happens. This will get the state of the threads at that moment and may help narrow the problem to application code or point to a bug. The option is "-XX:+ShowMessageBoxOnError" on the Sun JVM (which is not officially documented on the Sun Web site). When the JVM crashes, the program will prompt: "Do you want to debug the problem?" You can then take a thread dump of the JVM. This option will be available on the 8.1 SP2 version of the BEA JRockit JVM when it becomes available. However, in that version the corresponding option will be "-Djrockit.waitonerror".

The best option is to run a debugger on the resulting system core file to get a stacktrace of the native calls. The following information was also given in my last article (WLDJ, Vol. 3, issue 2) but it is being repeated here for consistency. This information may help point out the offending code to you; or, if you are unsure, then contact BEA Customer Support with this information so they can investigate the stacktrace more thoroughly. If you are on a Windows platform, then a "Dr. Watson" file may be produced. Please send this file to BEA Customer Support when opening a case. Otherwise, check the following "Unix" operating system values to make sure that they have already been properly set in order to generate a core file:

  1. Check the "ulimit -c" (configured size of the core file) at a system and user level to make sure that it is set and that the value is not set too low to produce a meaningful core file.
  2. Check the available disk space for the user (for example, is there a disk quota?).
  3. Also check the following parameter, which on Solaris is usually in /etc/system file and can be used to disable core files: set sys:coredumpsize=0.
  4. On Linux, the core dump is turned off by default on all systems. In RedHat Advanced Server 2.1 it should be under "/etc/security". There should be a self-explanatory file called limits.conf; within that file look for the word "core". If it is set to "0", then coredump files are disabled.
  5. On HPUX check the setting called "kernel parm maxdsiz" (max_per_proc_data_size, which increases the User Process Data Segment Size) from the old value of, say, 64M to something higher like 134M.

Please get a stacktrace (or backtrace) from your debugger. Here are the commands needed when using "dbx" or "gdb", which will work on most platforms:

a. dbx:

  • $ java -version: Need to use right version of JDK
  • $ ls /opt/bin/dbx: Need to know dbx location, or "which dbx"
  • $ export: DEBUG_PROG=/opt/bin/dbx (or wherever "dbx" is located)
  • $ <path to java command>/java corefile

Now you will be in the debugger. Execute the following commands:

  • (dbx) where: Shows a summary of the stack
  • (dbx) threads: Shows the state of the existing threads
  • (dbx) quit

b. gdb

  • java -version: Need to use right version of jdk
  • ls /usr/local/bin/gdb: Need to know gdb location or "which gdb"
  • export DEBUG_PROG=/usr/local/bin/gdb: Or wherever "gdb" is located)
  • <path to java command>/java corefile

Now you will be in the debugger. Execute the following commands:

  • (gdb) where: Shows a summary of the stack
  • (gdb) thr: Switch among threads or show the current thread
  • (gdb) info thr: Inquire about existing threads
  • (gdb) thread apply 1 bt: Apply a command to a list of threads, specifically the backtrace to thread #1)
  • (gdb) quit

If you don't have access to a debugger you can check to see if you have the "pstack" and "pmap" utilities on your operating system. If you do have those utilities (on some operating systems you have to download these utilities separately); you can run them on the system core file to gather information for support. The syntax of the command would be something like this:
$ /usr/proc/bin/pstack core
$ /usr/proc/bin/pmap core

Further Information
You can also go to http://support.bea.com and find some published solutions on core files. In the "Question" field type in "S-16147" to display some additional information about using pstack and pmap on Solaris.

Enabling/Disabling Dr. Watson
The drwtsn32.log files are similar to system core files on Unix. On Windows 2000, these files are found in the following directory: C:\Documents and Settings\All Users\Documents\DrWatson. After entering "drwtsn32 ?" in a DOS command window and hitting enter, the "Dr. Watson for Windows 2000" box appears. The DrWatson log file overview option will display a screen that explains the format of the drwtsn32.log files.

By default, Dr. Watson will be enabled when Windows NT is installed. To disable Dr. Watson, the following Registry value must be changed from 1 to 0 (zero): "\HKEY_LOCAL_MACHINE\SOFTWARE \Microsoft\Windows NT\CurrentVersion\AeDebug". An entry called "Auto" corresponds to how Dr. Watson will start up. To enable Dr. Watson, change the "Auto" value from 0 (zero) to 1. This will then launch whatever debugger, or application, is under the Debugger registry value. For Dr. Watson, the Debugger value should contain:

drwtsn32 -p %ld -e %ld -g

Links to On-Line Debugger Manuals

  1. gdb: www.gnu.org/manual/gdb-5.1.1/gdb.html
  2. dbx:
    a. Sun: http://docs.sun.com/db/doc/805-4948?q=DBX
    b. IBM: http://publib16.boulder.ibm.com/pseries/en_US/cmds/aixcmds2/dbx.htm
  3. adb: HP: http://docs.hp.com/hpux/onlinedocs/B2355-90680/00/00/8-con.html

If none of these hints help direct you towards a solution or an identifier in your application, then you should contact BEA Customer Support for further diagnosis. You can open a case with a valid support contract by logging in at http://support.bea.com/login.jsp.

More Stories By Steve Pozarycki

Steven Pozarycki is a backline developer relations engineer with BEA Systems, Customer Support Group. He specializes in troubleshooting and solving complex customer issues with their mission-critical applications on BEA products. Steve holds a bachelor's degree in computer science.

Reproduced with permission from BEA Systems.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
The 19th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportuni...
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
Pulzze Systems was happy to participate in such a premier event and thankful to be receiving the winning investment and global network support from G-Startup Worldwide. It is an exciting time for Pulzze to showcase the effectiveness of innovative technologies and enable them to make the world smarter and better. The reputable contest is held to identify promising startups around the globe that are assured to change the world through their innovative products and disruptive technologies. There w...
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abil...
With so much going on in this space you could be forgiven for thinking you were always working with yesterday’s technologies. So much change, so quickly. What do you do if you have to build a solution from the ground up that is expected to live in the field for at least 5-10 years? This is the challenge we faced when we looked to refresh our existing 10-year-old custom hardware stack to measure the fullness of trash cans and compactors.
The emerging Internet of Everything creates tremendous new opportunities for customer engagement and business model innovation. However, enterprises must overcome a number of critical challenges to bring these new solutions to market. In his session at @ThingsExpo, Michael Martin, CTO/CIO at nfrastructure, outlined these key challenges and recommended approaches for overcoming them to achieve speed and agility in the design, development and implementation of Internet of Everything solutions wi...
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
SYS-CON Events announced today Telecom Reseller has been named “Media Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
Smart Cities are here to stay, but for their promise to be delivered, the data they produce must not be put in new siloes. In his session at @ThingsExpo, Mathias Herberts, Co-founder and CTO of Cityzen Data, will deep dive into best practices that will ensure a successful smart city journey.
There is growing need for data-driven applications and the need for digital platforms to build these apps. In his session at 19th Cloud Expo, Muddu Sudhakar, VP and GM of Security & IoT at Splunk, will cover different PaaS solutions and Big Data platforms that are available to build applications. In addition, AI and machine learning are creating new requirements that developers need in the building of next-gen apps. The next-generation digital platforms have some of the past platform needs a...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices - comp...
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
I wanted to gather all of my Internet of Things (IOT) blogs into a single blog (that I could later use with my University of San Francisco (USF) Big Data “MBA” course). However as I started to pull these blogs together, I realized that my IOT discussion lacked a vision; it lacked an end point towards which an organization could drive their IOT envisioning, proof of value, app dev, data engineering and data science efforts. And I think that the IOT end point is really quite simple…
Identity is in everything and customers are looking to their providers to ensure the security of their identities, transactions and data. With the increased reliance on cloud-based services, service providers must build security and trust into their offerings, adding value to customers and improving the user experience. Making identity, security and privacy easy for customers provides a unique advantage over the competition.
Is the ongoing quest for agility in the data center forcing you to evaluate how to be a part of infrastructure automation efforts? As organizations evolve toward bimodal IT operations, they are embracing new service delivery models and leveraging virtualization to increase infrastructure agility. Therefore, the network must evolve in parallel to become equally agile. Read this essential piece of Gartner research for recommendations on achieving greater agility.
SYS-CON Events announced today that Venafi, the Immune System for the Internet™ and the leading provider of Next Generation Trust Protection, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Venafi is the Immune System for the Internet™ that protects the foundation of all cybersecurity – cryptographic keys and digital certificates – so they can’t be misused by bad guys in attacks...
For basic one-to-one voice or video calling solutions, WebRTC has proven to be a very powerful technology. Although WebRTC’s core functionality is to provide secure, real-time p2p media streaming, leveraging native platform features and server-side components brings up new communication capabilities for web and native mobile applications, allowing for advanced multi-user use cases such as video broadcasting, conferencing, and media recording.