What is a Deadlock on Java? Why you will Want to Avoid it

deadlock java

Java is one of the most widely used programming languages, developed by the brand “Oracle” and currently used for millions of users in the Internet. It’s used to develop a huge range of applications: from work environments software to simply games. The famous video game “Minecraft” is based on this programming language, and if you want to play it you will require to have Java installed. You can find here the java latest version free download.

Java is one of the easiest programming languages especially if you have learned C++ because his syntax is very similar, but not everything always goes as smooth as we want.

Today we are gonna talk about a specific problem that appears after making a coding mistake when trying to write some Java code: the deadlock.

deadlock java

A deadlock in Java happens when multiple threads are permanently locked, waiting for each otherĀ“s response. These are usually caused when different threads need to get the exact same locks but they don’t appear at the same time. Is relatively common to find deadlocks in Java programs using two or more threads when there is a synchronized keyword which provokes the thread currently being executed to accidentally block while waiting for the lock which should be assigned to the with the stated object.

So everytime you execute your written code it will give you the following wrong output, or something very close to this:

output

You get the idea… it basically bugs out and gives you this nonsense of a response. Who wouldn’t want to avoid a deadlock in Java? We will explain you here some basic guide on how to avoid deadlocks.

Now there are good and bad news. The good news part is that in most cases it has a quick and easy way to get this problem fixed. The bad news part is that Java programming can go very in-depth and if you are an advanced programmer (or trying to be one) you could find yourself scrolling through big amounts of posts in Java related forums desperately with a low chance of finding your specific cause of deadlock.

So what should we do when we find a deadlock in order to fix it?

The solution is simple assuming it’s not a complex and rich code text but rather on a beginner or intermediate level.

You just need to follow the following tips:

  •  Avoid using multiple threads (this is something usual on Swing, for instance)
  •  Do not leave multiple locks waiting all at once. If you need to, make sure you get the locks in the exact same order.
  •  Do not run outside code while you are holding for a lock.
  •  Try using locks that can be interrupted.

If you follow these tips you should be fixing the issue relatively quick in the majority of the cases.

However, each code text is different and this is no exception, you might have to try and experiment different configurations until you find the correct one.

One of the best places to find assistance to help you fix deadlocks in Java is the StackOverFlow online community, with hundreds of programmers coming from all the programming languages out there, not only Java, to make questions to others and get their questions answered as well.

Java

However if you don’t find the answer you are looking for on there, I can also recommend you this forum website called JavaForums: https://www.java-forums.org/forum.php

The design looks a bit outdated but there is a lot of valuable info in there. I personally have been using that page for years and always learned useful stuff and solved many programming issues I had on there.

CodeGuru forums are also a nice last choice when the other ones are not working for you, and once again the design seems outdated but the information provided by users on their forums is highly valuable and it isn’t by any means old. Nonetheless, you are better using the two other websites I provided due to the low activity on this last one.

Either way when you work with Java, make sure you get the Java latest version.

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