This is a first articles in series, where I would like to study effect of various HotSpot JVM options on duration of STW pauses associated with garbage collection.
This article will study how number of parallel threads affects duration of young collection Stop-the-World pause. HotSpot JVM has several young GC (more...)
There are bunch of graphical tools helping you to look inside of running JVM (VisualVm and JConsole are extremely helpful). Unfortunately, some times (almost always in my case), you may find yourself in SSH console on headless server side by side with your JVM (more...)
On Linux low entropy can cause certain operations to be very slow.
SSL operations need entropy to ensure randomness. Entropy is generated by the OS when you use the keyboard, the mouse or the disk.
If an SSL operation is missing entropy it will wait until enough is generated.
Recently, I was working on renewed version of Coherence data loss listener. New version provides simple utility to attach partition loader to any cache. Such partition loader is guaranteed to be called for every partition of newly created cache or after partition has been lost. Unlike CacheStore, partition loader (more...)
SSH offers a very convenient way to execute shell scripts remotely. Code like
are fairly easy to write and read.
But while remote execution itself is easy, writing actual distributed code is total mess.
I’m a Java guy. I (more...)
Autocomplete was not working for JSF tags in my Eclipse. I googled it and finally found the solution on http://www.mkyong.com/jsf2/how-to-make-eclipse-ide-supports-jsf-2-0/
The different thing I did is; I downloaded javax.faces-2.xx.xx.jar and saved in a specific folder. Then I created a user library with this jar. I did not use “jsf-api-xxx.jar and jsf-impl-xxx.jar“.
Year ago I installed Weblogic server + Oralce database server for a customer. Few months later my colleagues asked me whether something has changed in the environment or if something happened at the data center, because they started to see Java exceptions for unknown hostname for a web service they were calling and this was happening only from time to time. We’ve checked the firewall rules, DNS and all the stuff, but everything seemed to be working fine. The only solution by that time they came out was to add the hostname to the hosts file of the Weblogic server. (more...)
First you have the java interface way which I described here (more...)
I have a permanent job at the NetCracker‘s System Performance group. Recently I was offered to do one day job outside, on-site in another company, which coincidentally has an office close to NetCracker’s Moscow office. It was an opportunity to apply my skills in a completely different situation which I couldn’t miss; plus I’ve never done public presentations before and this was a good occasion to practice that. Here I’d like to write down some notes how the event went.
2 or 3 weeks before the event I’ve got the list of topics to work on. It included several (more...)
Oracle Database has had the possibility to run Java code inside the database for a long time. It's a very rare occasion when you need to use it but still. Here is one example I used to download content from HTTPS website that required user certificates for authentication. Please take the code below more as an example how to put simple Java code inside the database, not as a solution for user certificates authentication, because UTL_HTTP can do the same thing (although I wasn't successful in implementing it under 184.108.40.206).
First, load the Java source into database. (more...)