In the example above, a query that executed on a background worker thread created a dataset. While it is relatively easy to implement such a scenario, it is not as easy as simply retrieving a dataset as a return value from a single-threaded method. Another example is a simple for-loop. Imagine a for loop that runs times, incrementing a property on an object.
If two threads run at the same time executing the same loop, involving the same property, neither loop will run times. Instead, each loop is likely to run 50 times. Both loops together will iterate times exactly, but each loop individually will run some lower number of times. And to make matters worse, this problem will only occur in some rare cases based on coincidence, making it very hard to diagnose the problem. In fact, if someone attaches a debugger to the process to step through the code, the effect may not occur at all, since the developer is likely to step through one thread at a time.
Clearly, developers need better tools. Luckily though, this scenario is not all that likely to occur if your application uses different threads to perform different distinct tasks.
However, a similar effect can still occur when the UI thread attempts to refresh a grid bound to a dataset at the same time that the background thread is updating the data in the dataset. For these scenarios, there are well-defined and well-understood ways of circumventing the problem.
Background threads are never supposed to update the user interface directly. Similarly, if you use the background worker component, the problem can not occur at all, since that component is handling all such thread synchronization issues for you. So really, multithreading is not all that hard anymore. Nevertheless, it has to get simpler yet!
I have been part of discussions where developers and architects argue that the next step after object-oriented programming and service-oriented architecture should be thread-oriented programming.
If we need to write multithreaded code so our software runs well on multi-core systems, then our compilers and development environments should make it easy for us to do so. NET has taken big steps towards this goal, but developers still have to worry about low-level details of threading, rather than focusing on the business issue at hand.
At a recent developers event, I ended up spending a few hours at an airport waiting for a delayed plane together with my friend Jeffrey Richter co-founder of Wintellect. We had an excellent discussion about how to make multithreading easier for the masses. The background worker object is great, but I would much rather see an implementation scenario where we could write a few lines of code that query data and then assign it as a data source, and the compiler figures out that the first few lines run on the UI thread, the execution of the query should run on the background thread, and the assignment of the result needs to be synchronized back to the main thread.
This could happen implicitly in many scenarios, or it could be controlled by the developer in a declarative way. Perhaps certain methods could be flagged with an [Asynchronous ] attribute, for instance, instructing the compiler to use multithreading. It certainly is conceivable that the compiler or even the runtime can make that distinction and thus create the resulting code appropriately multithreaded.
Similarly, compilers, tools, and the Common Language Runtime could do a much better job at finding classic threading issues such as racing as illustrated in the loop example above or deadlocks and handle those scenarios in appropriate ways. The developer should not even have to be aware that multithreading is used in such scenarios. The code should just run better and smoother, resulting in better user experiences and in better use of hardware.
Developers no longer have to worry about multitasking and processes anymore; we should be able to get to the same point for multithreading. Sure, some people may want to deal with the low-level details of threading, just like some scenarios may require developers to worry about processes or App Domains. But for the majority of scenarios, multithreading should just work, or at the very least, be extremely simple to use.
Luckily, a lot of very smart people are thinking about this stuff, so we are likely to see drastically simplified threading scenarios in the not too distant future. For the time being however, we need to do a bit of extra work to support multithreading. You might find that it is much easier to implement than you think. My Subscriber Account Advertise Write. Training Home State of. Staffing Home Looking for Staff? Another utility class, SwingWorker , helps you with another common job: performing a task in a background thread, optionally updating the GUI when the task completes.
Basic support for threads in the Java platform is in the class java. It provides a thread API and provides all the generic behavior for threads. The actual implementation of concurrent operations is system-specific. These behaviors include starting, sleeping, running, yielding, and having a priority.
To implement a thread using the Thread class, you need to provide it with a run method that performs the thread's task. The section Implementing the Runnable Interface tells you how to do this. The next section, The Life Cycle of a Thread , discusses how to create, start, and stop a thread. Effective utilization of multiprocessor system: If we have multiple threads in a single process, then we can schedule multiple threads on multiple processor.
This will make process execution faster. Skip to content. Change Language. Related Articles. CPU Scheduling. Process Synchronization. Memory Management. Disk Management. Disk Scheduling. Operating System Quizes. When this happens, the thread generally loses all of its cached data.
If that thread resumes on another core then it has to build its cache from the start. Threading also introduces a special set of a problem known as multi-threading issue e. It's also very difficult to test a Java program that involves multiple threads. You cannot predict the order of execution in the case of multi-threading and without any synchronization. You should also read Java Concurrency in Practice to learn more about how to use threads effectively in Java. Share to Twitter Share to Facebook.
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