贪婪的线程在WebLogic下捕获了太多的JMS消息

Question

We encountered a problem under WebLogic 8.1 that we lived with but could never fix. We often queue up a hundred or more JMS messages, each of which represents a unit of work. Despite the fact that each message is of the same size and looks the same, one may take only seconds to complete while the next one represents 20 minutes of solid crunching.

Our problem is that each of the message driven beans we have doing the work of these messages ends up on a thread that seems to grab ten messages at a time (we think it is being done as a WebLogic optimization to keep from having to hit the queue over and over again for small messages). Then, as one thread after another finishes all of its small jobs and no new ones come in, we end up with a single thread log jammed on a long running piece of work with up to nine other items sitting waiting on it to finish, despite the fact that other threads are free and could start on those units of work.

Now we are at a point where we are converting to WebLogic 10 so it is a natural point to return to this problem and find out if there is any solution that we could implement so that either: a) each thread only grabs one JMS message at a time to process and leaves all the others waiting in the incoming queue, or b) it would automatically redistribute waiting messages (even ones already assigned to a particular thread) out to free threads. Any ideas?

Answer 1

Enable the Forward Delay and provide an appropriate value. This will cause the JMS Queue to redistribute messages to it's peers if they have not been processed in the configured time.

Taking a single message off the queue every time might be overkill - It's all a balance on the number of messages you are processing and what you gauge as an issue.

There are also multiple issues with JMS on WebLogic 10 depending on your setup. You can save yourself a lot of time and trouble by using the latest MP right from the start.

Answer 2

当线程在获取资源后可以执行“饥饿”操作时，处于饥饿状态的线程称为“贪婪线程”