Recently, I have discovered a fancy bug affecting few version of Linux kernel. Without any warnings JVM just hangs in GC pause forever. Root cause is a improper memory access in kernel code. This post by Gil Tene gives a good technical explanation with deep emotional coloring.
While this bug is not JVM specific, there are few other multithreaded processes you can find on typical Linux box.
This recent bug make me remember few other (more...)
In February of this year, Oracle University launched the PeopleSoft Learning Stream. Oracle's Learning Streams are short, educational vignettes. I was given the privilege of recording 6 streams:
- REST Query (more...)
A new feature in JEE7 is Batch Processing, an implementation of JSR 352 based on the programming model of Spring Batch. With batch processing, we understand the execution of a series of jobs (steps) , sequential or in parallel, without any user interaction. In this blog, we want to give a small overview of the capabilities of this new feature.
The code of this blog can be downloaded from here.
The zip file contains an Eclipse (more...)
Sometimes it just happens. You have a bloated Java application at your hand and it does not perform well. You may have built this application yourself or just got it as it is now. It doesn't matter, thing is - you do not have a slightest idea what is wrong here.
Java ecosystem have abundance of diagnostic tools (thank for interfaces exposed at JVM itself), but they are mostly focused on some specific narrow kinds (more...)
I had a need to Ping a server to see if the server could get to it. I also tried to post to it. This code could be helpful for others, so I want to share it. A post should normally go through the Integration Broker, but I first developed it at a time when I had a product that was supposed to go on servers with diverse versions of Integration Broker.
The Ping code (more...)
sudo -u tomcat jstack 1853 | grep " (more...)
150 GiB worth of JVM heap dump is laying on hard drive and I need analyze specific problem detected in that process.
This is a dump of proprietary hybrid of in-memory RDBMS and CEP system, I'm responsible for. All data are stored in Java heap, so heap size of some installation is huge (400 GiB heap is largest to the date).
Problem of analyzing huge heap dumps were on my radar for some time, so (more...)
If you have a sorted collection of elements, how would you find index of specific value?
"Binary search" is likely to be your answer.
Algorithms theory is teaching us what binary search is most optimal algorithm for this task with log(N) complexity.
Well, hash table can do better, if you need to find key by exact match. In many cases, though, you have reasons to have your collection sorted, not hashed.
On my job, I'm (more...)
Well, this blog posting is not about explaining the (more...)