When is threadlocal used

After all, who sets parameters and uses a different method to fetch the results? As a general rule, do not consider property editors thread-safe. Another group of classes is also not thread-safe, and they have caught a few developers by surprise: the java. If it is possible for multiple threads to access these at the same time, you should wrap them in a ThreadLocal , or otherwise synchronize access.

To wrap a Format, or any other non-thread-safe object in a ThreadLocal , you need a variable for the ThreadLocal that is easily access by your code. Make sure that your code can get to it anytime it needs it. Just as we did above, you can override initalValue or use set to place the non-thread-safe object in the ThreadLocal.

You may even want to create a static class for the sole purpose of holding on to the ThreadLocal that has your non-thread-safe object. Anywhere in your code where you want to convert a point, ask the PointEditorHolder for an editor, and you know your threads will not tangle. Just to be sure, you confirm with a test:. In a setting such as a Web application, you may have filters that can recognize particular aspects of the request that you want to use later in the code in unrelated contexts.

You can use it to keep track of the authentication of the current user; of localization options such as language or date formatting; or site theme preferences. You can use the request object to hold each of these, of course, but then you need to pass the request object all over the code. With a ThreadLocal , you only these when you need them.

I think of these as global-ish values. But with much better results. Multithreaded programming is not easy, even with ThreadLocals. You must understand the implications of using them. When to use ThreadLocal? How to use ThreadLocal? Instead, give each thread its own instance of the object to work with. A good alternative to synchronization or threadlocal is to make the variable a local variable.

Local variables are always thread safe. The only thing which may prevent you to do this is your application design constraints. In wabapp server, it may be keep a thread pool, so a ThreadLocal var should be removed before response to the client, since current thread may be reused by next request.

Was this post helpful? Let us know if you liked the post. Restarting threads using UncaughtExceptionHandler. Creating Threads Using java. Hi Lokesh, Thank you for your interesting post. You are right. Math class ctd Karatsuba's algorithm for multiplication Generating random numbers in Java: the Java random class and beyond Sources of entropy Using random numbers for simulations: Random.

Random Using java. Random How does java. Random work and how good is it? Subclassing java. Random Randomness of bits with LCGs 'java. Introductions to Exceptions and error handling in Java Exceptions in Java: when to catch and when to throw?

October 15, at pm. Andrey says:. July 16, at am. July 12, at pm. Muhammad Gelbana says:. October 16, at am. Sriharsha says:. September 12, at pm. June 9, at pm. June 10, at am. March 22, at am. August 20, at am. October 6, at am. July 26, at am. May 4, at pm. Pankaj Chopra says:. February 22, at pm. February 23, at am.