|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.
Unless your company can spend a lot of money on new technology, re-engineering your environment and hiring a comprehensive cybersecurity team, you will most likely move to the cloud or seek external service partnerships. In his session at 18th Cloud Expo, Darren Guccione, CEO of Keeper Security, revealed what you need to know when it comes to encryption in the cloud.
Jul. 24, 2016 05:00 PM EDT Reads: 2,339
We're entering the post-smartphone era, where wearable gadgets from watches and fitness bands to glasses and health aids will power the next technological revolution. With mass adoption of wearable devices comes a new data ecosystem that must be protected. Wearables open new pathways that facilitate the tracking, sharing and storing of consumers’ personal health, location and daily activity data. Consumers have some idea of the data these devices capture, but most don’t realize how revealing and...
Jul. 24, 2016 05:00 PM EDT Reads: 2,013
What are the successful IoT innovations from emerging markets? What are the unique challenges and opportunities from these markets? How did the constraints in connectivity among others lead to groundbreaking insights? In her session at @ThingsExpo, Carmen Feliciano, a Principal at AMDG, will answer all these questions and share how you can apply IoT best practices and frameworks from the emerging markets to your own business.
Jul. 24, 2016 04:15 PM EDT Reads: 1,538
Ask someone to architect an Internet of Things (IoT) solution and you are guaranteed to see a reference to the cloud. This would lead you to believe that IoT requires the cloud to exist. However, there are many IoT use cases where the cloud is not feasible or desirable. In his session at @ThingsExpo, Dave McCarthy, Director of Products at Bsquare Corporation, will discuss the strategies that exist to extend intelligence directly to IoT devices and sensors, freeing them from the constraints of ...
Jul. 24, 2016 03:45 PM EDT Reads: 1,718
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
Jul. 24, 2016 03:30 PM EDT Reads: 885
Extracting business value from Internet of Things (IoT) data doesn’t happen overnight. There are several requirements that must be satisfied, including IoT device enablement, data analysis, real-time detection of complex events and automated orchestration of actions. Unfortunately, too many companies fall short in achieving their business goals by implementing incomplete solutions or not focusing on tangible use cases. In his general session at @ThingsExpo, Dave McCarthy, Director of Products...
Jul. 24, 2016 03:15 PM EDT Reads: 1,666
Traditional IT, great for stable systems of record, is struggling to cope with newer, agile systems of engagement requirements coming straight from the business. In his session at 18th Cloud Expo, William Morrish, General Manager of Product Sales at Interoute, outlined ways of exploiting new architectures to enable both systems and building them to support your existing platforms, with an eye for the future. Technologies such as Docker and the hyper-convergence of computing, networking and sto...
Jul. 24, 2016 03:00 PM EDT Reads: 1,001
WebRTC is bringing significant change to the communications landscape that will bridge the worlds of web and telephony, making the Internet the new standard for communications. Cloud9 took the road less traveled and used WebRTC to create a downloadable enterprise-grade communications platform that is changing the communication dynamic in the financial sector. In his session at @ThingsExpo, Leo Papadopoulos, CTO of Cloud9, discussed the importance of WebRTC and how it enables companies to focus...
Jul. 24, 2016 02:30 PM EDT Reads: 752
With an estimated 50 billion devices connected to the Internet by 2020, several industries will begin to expand their capabilities for retaining end point data at the edge to better utilize the range of data types and sheer volume of M2M data generated by the Internet of Things. In his session at @ThingsExpo, Don DeLoach, CEO and President of Infobright, discussed the infrastructures businesses will need to implement to handle this explosion of data by providing specific use cases for filterin...
Jul. 24, 2016 02:00 PM EDT Reads: 1,185
IoT generates lots of temporal data. But how do you unlock its value? You need to discover patterns that are repeatable in vast quantities of data, understand their meaning, and implement scalable monitoring across multiple data streams in order to monetize the discoveries and insights. Motif discovery and deep learning platforms are emerging to visualize sensor data, to search for patterns and to build application that can monitor real time streams efficiently. In his session at @ThingsExpo, ...
Jul. 24, 2016 01:30 PM EDT Reads: 804
Early adopters of IoT viewed it mainly as a different term for machine-to-machine connectivity or M2M. This is understandable since a prerequisite for any IoT solution is the ability to collect and aggregate device data, which is most often presented in a dashboard. The problem is that viewing data in a dashboard requires a human to interpret the results and take manual action, which doesn’t scale to the needs of IoT.
Jul. 24, 2016 12:00 PM EDT Reads: 1,872
Internet of @ThingsExpo has announced today that Chris Matthieu has been named tech chair of Internet of @ThingsExpo 2016 Silicon Valley. The 6thInternet of @ThingsExpo will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Jul. 24, 2016 12:00 PM EDT Reads: 1,886
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...
Jul. 24, 2016 11:00 AM EDT Reads: 1,308
Much of IT terminology is often misused and misapplied. Modernization and transformation are two such terms. They are often used interchangeably even though they mean different things and have very different connotations. Indeed, it is somewhat safe to assume that in IT any transformative effort is likely to also have a modernizing effect, and thus, we can see these as levels of improvement efforts. However, many businesses are being led to believe if they don’t transform now they risk becoming ...
Jul. 24, 2016 11:00 AM EDT Reads: 1,108
CenturyLink has announced that application server solutions from GENBAND are now available as part of CenturyLink’s Networx contracts. The General Services Administration (GSA)’s Networx program includes the largest telecommunications contract vehicles ever awarded by the federal government. CenturyLink recently secured an extension through spring 2020 of its offerings available to federal government agencies via GSA’s Networx Universal and Enterprise contracts. GENBAND’s EXPERiUS™ Application...
Jul. 24, 2016 11:00 AM EDT Reads: 1,792
What does it look like when you have access to cloud infrastructure and platform under the same roof? Let’s talk about the different layers of Technology as a Service: who cares, what runs where, and how does it all fit together. In his session at 18th Cloud Expo, Phil Jackson, Lead Technology Evangelist at SoftLayer, an IBM company, spoke about the picture being painted by IBM Cloud and how the tools being crafted can help fill the gaps in your IT infrastructure.
Jul. 24, 2016 11:00 AM EDT Reads: 2,024
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, 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. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
Jul. 24, 2016 09:30 AM EDT Reads: 1,080
The best-practices for building IoT applications with Go Code that attendees can use to build their own IoT applications. In his session at @ThingsExpo, Indraneel Mitra, Senior Solutions Architect & Technology Evangelist at Cognizant, provided valuable information and resources for both novice and experienced developers on how to get started with IoT and Golang in a day. He also provided information on how to use Intel Arduino Kit, Go Robotics API and AWS IoT stack to build an application tha...
Jul. 24, 2016 08:45 AM EDT Reads: 911
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...
Jul. 24, 2016 08:30 AM EDT Reads: 2,067
It’s 2016: buildings are smart, connected and the IoT is fundamentally altering how control and operating systems work and speak to each other. Platforms across the enterprise are networked via inexpensive sensors to collect massive amounts of data for analytics, information management, and insights that can be used to continuously improve operations. In his session at @ThingsExpo, Brian Chemel, Co-Founder and CTO of Digital Lumens, will explore: The benefits sensor-networked systems bring to ...
Jul. 24, 2016 08:30 AM EDT Reads: 1,473