|By Steve Pozarycki||
|March 10, 2004 12:00 AM EST||
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.
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:
- 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.
- Check the available disk space for the user (for example, is there a disk quota?).
- 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.
- 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.
- 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:
- $ 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
- 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
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
- gdb: www.gnu.org/manual/gdb-5.1.1/gdb.html
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
- 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.
SYS-CON Events announced today that Micron Technology, Inc., a global leader in advanced semiconductor systems, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Micron’s broad portfolio of high-performance memory technologies – including DRAM, NAND and NOR Flash – is the basis for solid state drives, modules, multichip packages and other system solutions. Backed by more than 35 years of technology leadership, Micron's memory solutions enable the world's most innovative computing, consumer,...
Aug. 30, 2015 01:30 PM EDT Reads: 203
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies leverage disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 17th Cloud Expo, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevOps to advance innovation and increase agility. Specializing in designing, imple...
Aug. 30, 2015 01:00 PM EDT Reads: 257
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 30, 2015 10:30 AM EDT Reads: 861
Consumer IoT applications provide data about the user that just doesn’t exist in traditional PC or mobile web applications. This rich data, or “context,” enables the highly personalized consumer experiences that characterize many consumer IoT apps. This same data is also providing brands with unprecedented insight into how their connected products are being used, while, at the same time, powering highly targeted engagement and marketing opportunities. In his session at @ThingsExpo, Nathan Treloar, President and COO of Bebaio, will explore examples of brands transforming their businesses by t...
Aug. 30, 2015 10:15 AM EDT Reads: 208
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
Aug. 30, 2015 09:15 AM EDT Reads: 602
With the proliferation of connected devices underpinning new Internet of Things systems, Brandon Schulz, Director of Luxoft IoT – Retail, will be looking at the transformation of the retail customer experience in brick and mortar stores in his session at @ThingsExpo. Questions he will address include: Will beacons drop to the wayside like QR codes, or be a proximity-based profit driver? How will the customer experience change in stores of all types when everything can be instrumented and analyzed? As an area of investment, how might a retail company move towards an innovation methodolo...
Aug. 30, 2015 09:15 AM EDT Reads: 432
The Internet of Things (IoT) is about the digitization of physical assets including sensors, devices, machines, gateways, and the network. It creates possibilities for significant value creation and new revenue generating business models via data democratization and ubiquitous analytics across IoT networks. The explosion of data in all forms in IoT requires a more robust and broader lens in order to enable smarter timely actions and better outcomes. Business operations become the key driver of IoT applications and projects. Business operations, IT, and data scientists need advanced analytics t...
Aug. 30, 2015 08:30 AM EDT Reads: 385
A producer of the first smartphones and tablets, presenter Lee M. Williams will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater. In his session at @ThingsExpo, Lee Williams, COO of ETwater, will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater.
Aug. 30, 2015 07:00 AM EDT Reads: 116
SYS-CON Events announced today that IceWarp will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. IceWarp, the leader of cloud and on-premise messaging, delivers secured email, chat, documents, conferencing and collaboration to today's mobile workforce, all in one unified interface
Aug. 30, 2015 01:00 AM EDT Reads: 385
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Aug. 30, 2015 01:00 AM EDT Reads: 429
While many app developers are comfortable building apps for the smartphone, there is a whole new world out there. In his session at @ThingsExpo, Narayan Sainaney, Co-founder and CTO of Mojio, will discuss how the business case for connected car apps is growing and, with open platform companies having already done the heavy lifting, there really is no barrier to entry.
Aug. 29, 2015 10:30 AM EDT Reads: 112
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Aug. 29, 2015 07:45 AM EDT Reads: 133
As more and more data is generated from a variety of connected devices, the need to get insights from this data and predict future behavior and trends is increasingly essential for businesses. Real-time stream processing is needed in a variety of different industries such as Manufacturing, Oil and Gas, Automobile, Finance, Online Retail, Smart Grids, and Healthcare. Azure Stream Analytics is a fully managed distributed stream computation service that provides low latency, scalable processing of streaming data in the cloud with an enterprise grade SLA. It features built-in integration with Azur...
Aug. 28, 2015 07:45 PM EDT Reads: 200
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome,” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
Aug. 28, 2015 06:00 PM EDT Reads: 332
Akana has announced the availability of the new Akana Healthcare Solution. The API-driven solution helps healthcare organizations accelerate their transition to being secure, digitally interoperable businesses. It leverages the Health Level Seven International Fast Healthcare Interoperability Resources (HL7 FHIR) standard to enable broader business use of medical data. Akana developed the Healthcare Solution in response to healthcare businesses that want to increase electronic, multi-device access to health records while reducing operating costs and complying with government regulations.
Aug. 26, 2015 07:00 AM EDT Reads: 124
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
Aug. 2, 2015 11:15 AM EDT Reads: 549
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 476
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
Jul. 30, 2015 07:30 PM EDT Reads: 1,563
MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs. The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.
Jul. 30, 2015 02:30 PM EDT Reads: 276
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...
Jul. 30, 2015 12:00 PM EDT Reads: 2,225