Welcome!

IBM Cloud Authors: Zakia Bouachraoui, Elizabeth White, Yeshim Deniz, Pat Romanski, Liz McMillan

Related Topics: IBM Cloud

IBM Cloud: Article

WebSphere Application Server Java Dumps

Description and problem determination

Example 2 – You can see the Compiled Code and Inlined Compiled Code references where the line number in a typical stack trace is observed. Threads have states, as shown in Example 1. Most threads will indicate either an R or a CW state. The following is a list of states and a brief description of each:
  • R – A Runnable Thread that can run or is running. On platforms such as AIX and Linux, you can see which thread is actually running via the XHPI - Current Thread Details.
  • CW – A Conditional Wait Thread is waiting on a condition variable, typically a certain condition to occur. For example, a thread may be waiting for a resource to become available.
  • MW – A Monitor Wait Thread is waiting on a monitor lock.
  • S – A Suspended Thread is suspended.

Looking into Monitors – LK Dump Routine
The following table shows how the LK Dump routine is broken down into five subsections:

  • Monitor Pool Info provides basic monitor information, such as, the current total number of monitors, and so on.
  • Monitor Pool Dump lists the monitors that exist in the JVM at the time of the Java dump along with the threads waiting for that particular monitor and the owner of each monitor. Monitors can be owned or not owned as indicated in the file. You can use this section to identify any problems, such as, too many threads waiting on a monitor.
  • JVM System Monitor Dump is similar to the monitor pool dump except that instead of listing any monitor, it lists all of the system monitors on the JVM for which the Java dump was captured.
  • Java Object Monitor Dump is the same as the monitor pool dump except that additional JVM internal information is provided.
  • Thread Identifiers provide an association between the XM dump routine and the monitor pool dump. You can use this section as a pointer to the location of the problem identified in the monitor pool dump.

Looking into Classloaders – CL Dump Routine
The CL dump routine shows the list of class loaders and their corresponding classes. The respective address for each class and class loader is also shown in this section of the Java dump. The type for each class loader is shown to the left of the name of the class loader indicating if the class loader is primordial, extension, shareable, middleware, system, or trusted.

WebSphere Application Server Java Dumps
There are several types of threads that appear when you generate a Java dump in a WebSphere Application Server. The following list contains the types of threads that reside in most WebSphere Application Server Java dumps:
  • Server Socket threads – Server Socket threads listen for the incoming request in the Web container component of WebSphere Application Server. When the threads get a request they delegate the work to the Servlet Engine Transport thread. For example, the Server Socket thread listens to incoming Web requests (port 9080, by default) and delegates the request to the Servlet Engine Transport threads. When there’s a backlog of connections, the Server Socket threads operate like the Apache Web server, which means that there’ll be a maximum of 511 backlog connections supported. When there are more than 511 clients in addition to the Servlet Engine Transport thread maximum, the next client will be refused service.
3XMTHREADINFO “ServerSocket[addr=0.0.0.0/
  0.0.0.0,port=0,localport=9085]” (TID:0x10628F00,
sys_thread_t:0x4D87A80, state:R, native ID:0x9C4) 
  prio=5
4XESTACKTRACE at java.net.PlainSocketImpl.
  socketAccept(Native Method)
4XESTACKTRACE at java.net.PlainSocketImpl.
  accept(PlainSocketImpl.java(Compiled Code))
4XESTACKTRACE at java.net.ServerSocket.
  implAccept(ServerSocket.java(Compiled Code))
4XESTACKTRACE at java.net.ServerSocket.
  accept(ServerSocket.java(Compiled Code))
4XESTACKTRACE at com.ibm.ws.http.HttpTransport.
  run(HttpTransport.java:235)
4XESTACKTRACE at java.lang.Thread.run(Thread.java:568)
Example 3 – This example shows the Server Socket thread listening to port 9085 on an IBM V1.4.1 JVM and accepting a connection.
  • Servlet Engine Transport threads – WebSphere Application Server maintains the Servlet Engine Transport threads in a thread pool. These threads execute the service methods of the servlets. Depending on the settings for the thread pool and the number of new incoming requests, you can create transport threads or use ones from the thread pool. The number of transport threads occupied by requests coincides with the number of unique clients connected to the Web container. If you enable the KeepAlive parameter, the connection persists as long as you specify through this parameter and the Servlet Engine Transport thread will be reserved for a particular user during this time. In other words, a blocking Input/Output (I/O) operation is performed in the Servlet Engine Transport thread.
3XMTHREADINFO “Servlet.Engine.Transports : 0” 
  (TID:0x10631CC8, sys_thread_t:0x4E397A8, state:R,
native ID:0xEF4) prio=5
4XESTACKTRACE at java.net.SocketInputStream.
  socketRead0(Native Method)
4XESTACKTRACE at java.net.SocketInputStream.
  read(SocketInputStream.java(Compiled Code))
4XESTACKTRACE at com.ibm.ws.io.Stream.read(Stream.
  java:17)
4XESTACKTRACE at com.ibm.ws.io.ReadStream.
  readBuffer(ReadStream.java(Compiled Code))
4XESTACKTRACE at com.ibm.ws.io.ReadStream.
  read(ReadStream.java(Compiled Code))
4XESTACKTRACE at com.ibm.ws.http.HttpRequest.
  readRequestLine(HttpRequest.java(Compiled Code))
4XESTACKTRACE at com.ibm.ws.http.HttpRequest.
  readRequest(HttpRequest.java:302)
4XESTACKTRACE at com.ibm.ws.http.HttpConnection.
  readAndHandleRequest(HttpConnection.java:596)
4XESTACKTRACE at com.ibm.ws.http.HttpConnection.
  run(HttpConnection.java:443)
4XESTACKTRACE at com.ibm.ws.util.ThreadPool$Worker.
  run(ThreadPool.java(Compiled Code))

More Stories By Dipak Patel

Dipak M. Patel is a Senior IT specialist for IBM Software Services Performance Technology group. He has been focused on solving complex performance related problems involving WebSphere Application Server and Business Integration solutions. Dipak has a bachelors degree in Electrical Engineering and a masters degree in Computer Science from the University of Akron.

More Stories By Michel Betancourt

Michel Betancourt has been focused on WebSphere Application Server problem determination while part of IBM’s World Wide WebSphere Solutions War Room team. He was graduated from Florida International University in 2001 with a bachelor’s in computer engineering.

More Stories By Lorrie Barber

Lorrie M. Barber has been in WebSphere Application Server information development since 2001 focusing on system administration. She has a BS in computer information systems from the University of North Carolina at Wilmington and an MS in technical communication from North Carolina State University.

Comments (2)

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.


IoT & Smart Cities Stories
Moroccanoil®, the global leader in oil-infused beauty, is thrilled to announce the NEW Moroccanoil Color Depositing Masks, a collection of dual-benefit hair masks that deposit pure pigments while providing the treatment benefits of a deep conditioning mask. The collection consists of seven curated shades for commitment-free, beautifully-colored hair that looks and feels healthy.
The textured-hair category is inarguably the hottest in the haircare space today. This has been driven by the proliferation of founder brands started by curly and coily consumers and savvy consumers who increasingly want products specifically for their texture type. This trend is underscored by the latest insights from NaturallyCurly's 2018 TextureTrends report, released today. According to the 2018 TextureTrends Report, more than 80 percent of women with curly and coily hair say they purcha...
The textured-hair category is inarguably the hottest in the haircare space today. This has been driven by the proliferation of founder brands started by curly and coily consumers and savvy consumers who increasingly want products specifically for their texture type. This trend is underscored by the latest insights from NaturallyCurly's 2018 TextureTrends report, released today. According to the 2018 TextureTrends Report, more than 80 percent of women with curly and coily hair say they purcha...
We all love the many benefits of natural plant oils, used as a deap treatment before shampooing, at home or at the beach, but is there an all-in-one solution for everyday intensive nutrition and modern styling?I am passionate about the benefits of natural extracts with tried-and-tested results, which I have used to develop my own brand (lemon for its acid ph, wheat germ for its fortifying action…). I wanted a product which combined caring and styling effects, and which could be used after shampo...
The platform combines the strengths of Singtel's extensive, intelligent network capabilities with Microsoft's cloud expertise to create a unique solution that sets new standards for IoT applications," said Mr Diomedes Kastanis, Head of IoT at Singtel. "Our solution provides speed, transparency and flexibility, paving the way for a more pervasive use of IoT to accelerate enterprises' digitalisation efforts. AI-powered intelligent connectivity over Microsoft Azure will be the fastest connected pat...
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Druva is the global leader in Cloud Data Protection and Management, delivering the industry's first data management-as-a-service solution that aggregates data from endpoints, servers and cloud applications and leverages the public cloud to offer a single pane of glass to enable data protection, governance and intelligence-dramatically increasing the availability and visibility of business critical information, while reducing the risk, cost and complexity of managing and protecting it. Druva's...
BMC has unmatched experience in IT management, supporting 92 of the Forbes Global 100, and earning recognition as an ITSM Gartner Magic Quadrant Leader for five years running. Our solutions offer speed, agility, and efficiency to tackle business challenges in the areas of service management, automation, operations, and the mainframe.