In many cases, like in the case of a memory leak, that second option is the only good solution. A memory leak happens when the application creates more and more objects and never releases them. The garbage collector cannot collect those objects and the application will eventually run out of memory. At this point, the JVM will throw an OOM ( OutOfMemoryError).Ī memory leak can be very latent. For instance, the application might behave flawlessly during development and QA. However, it suddenly throws a OOM after several days in production at customer site. To solve that issue, you first need to find the root cause of it. The root cause can be very hard to find in development if the problem cannot be reproduced. Follow those steps to find the root cause of the OOM: Step 1. This will tell the JVM to produce a heap dump when a OOM occurs: Start the application with the VM argument -XX:+HeapDumpOnOutOfMemoryError. Well, if you cannot reproduce the problem in dev, you may have to use the production environment. Investigate the issue using the heap dump file When you reproduce the problem and the application throws an OOM, it will generate a heap dump file. Use VisualVM to read the heap dump file and diagnose the issue. VisualVM is a program located in JDK_HOME/bin/jvisualvm. The heap dump file has all information about the memory usage of the application. Here is a screenshot of VisualVM with a heap dump loaded: It allows you to navigate the heap and see which objects use the most memory and what references prevent the garbage collector from reclaiming the memory. This will give you very strong hints and you will (hopefully) be able to find the root cause of the problem. The problem could be a cache that grows indefinitely, a list that keeps collecting business-specific data in memory, a huge request that tries to load almost all data from database in memory, etc. Once you know the root cause of the problem, you can elaborate solutions to fix it. In case of a cache that grows indefinitely, a good solution could be to set a reasonable limit to that cache. In case of a query that tries to load almost all data from database in memory, you may have to change the way you manipulate data you could even have to change the behavior of some functionalities of the application. An automatic storage management system reclaims heap. In a heap, all class instances and the array is allocated. If you do not want to wait for an OOM or if you just want to see what is in memory now, you can manually generate heap dump. In Java, a heap is a chunk of memory which is shared among all threads. Here 2 options to manually trigger a heap dump. Open VisualVM ( JDK_HOME/bin/jvisualvm), right-click on the process on the left pane and select Heap Dump. If you do not have a graphical environment and can’t use vnc ( VisualVM needs a graphical environment), use jps and jmap to generate the heap dump file. Those programs are also located in JDK_HOME/bin/.SongKong understands Classical music. The Metadata demands for Classical are very different to Pop/Rock music, credit is usually given to not only the performer but also theĬonductor, orchestra and composer. In Pop/Rock an album usually represents the artistic intent of the artist, i.e. The album was conceivedĪnd created as a single body of work. In Classical it is more complicated, Classical composers work in terms of Symphonies or Sonatas When Classical music is released as an album it may only contain part of a These works comprise sub works or movements, and there may be additional levels. Work, or conversely multiple works, so the album grouping may not be the most important grouping. SongKong identifies Classical releases and captures this additional information in dedicated metadata fields. It can also identify other Classical information such as the Opus No and the performers with their instruments. SongKong can automatically update the new iTunes Work and Movement fields.Ĭlick here to find out more about Classical Music Tag editing. SongKong is available for both the Mac and PC, with support for OS X, Windows and Linux. So if you have a PC at work and a Mac at home you can use SongKong effectively in both settings. SongKong support comes direct from the developer. As the developer I am determined to make SongKong the best tagger available for all platforms, and therefore I actively encourage comments, bug reports and questions. I value your feedback and queries and aim to be as responsive as possible SongKong uses the professional JIRA issue tracking for tracking issues that cannot be resolved within a day. I have also previously worked as a developer for MusicBrainz, responsible for writing their search code. Let’s see an example that generates a core dump using JNI.This includes what people use to search for albums on MusicBrainz and their web service. The command above captures the thread dump and saves it in a txt file for further analysis. For (int i = 0 i slow-running-task-thread-dump.txt
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |