This Knowledge Collection is a focused compilation of links to documents for Out of Memory OOM.
List of top content for Out of Memory
Other Knowledge Collections for WebSphere Application Server
List of content for Out of Memory OOM
1. Disabling AIO (Asynchronous Input/Output) native transport in WebSphere Application Server (1366862)
IBM Support might request you to disable the AIO native transport code. In certain cases, this code can have a fairly large native memory footprint, and if the application server is short on native memory, disabling the AIO native transport can increase the available address space for native memory.
2. How to read a heapdump generated in .phd format (1190476)
Starting with Java SDK 1.4.2 SR1, the default heapdump format has changed. The default format for a heapdump will be "portable heap dump format" and the file will have an "*.phd" extension.
3. Troubleshooting native memory issues (1373312)
There are two types of memory problems which will throw an OutOfMemoryError: If a Java object cannot be allocated or if there is no more memory available for native code allocations (c malloc) or threads. The first case is called Java heap exhaustion and the second, a native memory issue. Finding the users of native memory can be a lengthy process, as there is no way of knowing which code allocated the native memory. There are no comparable heapdumps for native memory, so we have to use trial and error, going through each of the potential native memory users until we find the one that is causing the problem. Following are the most common causes of native memory issues in WebSphere Application Server, so you should try them first. They are all trying to reduce the native memory used
4. Potential native memory use in WebSphere Application Server thread pools (1368248)
The WebSphere Application Server thread pools can leak ThreadLocal objects when threads are destroyed (java.lang.ThreadLocal). ThreadLocal objects can have a significant native memory component, so you can see a native memory leak if there is a ThreadLocal leak.
5. Setting the WebSphere Application Server WebContainer to synchronous mode (1317658)
The WebContainers use of asynchronous data transfer may use a large number of buffers in native memory to write an application response. This predominately occurs when large application responses are being transferred (for example a PDF, large images, the dmgr updating the nodeagents, ,etc) but may also occur with normal size application responses. If the amount of native memory used by this is too large, we can enable synchronous mode which will reduce the amount of memory used to store responses.
6. Getting Heapdumps on the Solaris platform (1242314)
By default, Sun's Java Virtual Machine (JVM) does not produce heapdumps for memory diagnostics. The required steps to enable this functionality (if supported) is dependant on what level of the JVM is installed.
7. How to manually generate a Heapdump in WebSphere on Windows (1384926)
How to generate a heapdump without waiting for an OutOfMemoryError condition to occur.
8. How to manually generate a Heapdump in WebSphere on AIX and Linux (1297060)
How to manually generate a heapdump without waiting for an OutOfMemoryError condition to occur.
9. Preventing mark stack overflows during garbage collection in the Java SDK (1164724)
In the Java SDK shipped for AIX , Linux and Windows , the mark stack is created during the first phase of garbage collection when live objects are marked for retention. Objects are taken off the stack and any references held by the object are added. Mark stack overflow in itself does not indicate an error condition, but it does result in increased CPU utilization.
10. Technique for Increasing Available Native Memory on AIX 32-bit Java (1450144)
If you are seeing native OutOfMemoryError problems on AIX 32-bit, how can you increase the available native memory?
11. "Dark matter" on the Heap Can Cause Performance issues due to excessive Garbage Collection (1214654)
Blocks of free heap space less than 512 bytes in length and lying between two allocated objects are known as "dark matter." This space is are not released by the normal mark/sweep phase of the IBM Java SDK garbage collection cycle. This space is only collected during a compaction phase or when the objects adjacent to them are collected. In some cases, the amount of dark matter can grow over time leading to performance issues and heap fragmentation.
12. Improper closing of deflater object results in native memory exhaustion (1227106)
If a deflater object is not explicitly closed and ended, a native memory leak occurs. This leak can result in OutOfMemoryError's and/or Java Virtual Machine (JVM) crashes.
13. Open Mic Replay: OutOfMemory(OOM) Issues in WebSphere Application Server (7018423)
This session gives you a chance to ask questions on how to troubleshoot OOM issues in WebSphere Application Server. Topics include how to identify native and Java heap OOM, documentation to collect, analyzing data using different tools, best practices and recommendations on common issues.
14. OutOfMemoryError (OOM) and Leak Detected in IBM PoolManager When Using Oracle JDBC Driver (1421030)
OutOfMemoryError or unexpectedly high heap utilization when using Oracle JDBC Driver and stored procedures. Leak detection logic may point to com.ibm.ejs.j2c.PoolManager however the leak is due to how stored procedures are processed by the JDBC Driver.
15. Configuring the k-cluster using heapdump (1230492)
HeapAnalyzer can be used to determine an appropriate k-cluster value for your JVM, providing a healthier Java heap
Other Knowledge Collections for WebSphere Application Server
1. Knowledge Collection: Migrating from WebSphere Application Server (7008725)
2. Knowledge Collection: Migrating to (or from) WebSphere Application Server V6.0 (7008727)
3. Knowledge Collection: Migrating to WebSphere Application Server V7.0 (7013842)
4. Knowledge Collection: Java Message Service (JMS) for WebSphere Application Server (7020347)
5. Knowledge Collection: Migration planning for WebSphere Application Server (7008724)
6. Knowledge Collection: IBM Support Newsletters (7011428)
7. Knowledge Collection: Migrating from other Application Servers to WebSphere Application Server (7008729)
8. Knowledge Collection: Migrating to (or from) WebSphere Application Server V6.1 (7008728)
9. Knowledge Collection: Plug-in for WebSphere Application Server (7021301)
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