[SNMP4J] [BugReport][SNMP4J-2.2.3] Concurrency bug in org.snmp4j.util.ThreadPool.

[Dmitrii Krendelev]

Hi,

We have found quite a critical bug in org.snmp4j.util.ThreadPool.execute(WorkerTask task) method. It has an execute method below

    public synchronized void execute(WorkerTask task)
    {
        while (true)
        {
            // here we check if some TaskManager-thread is free to execute the task.
            try
            {
                wait(); // wait until some TaskManager-thread notify that it finished a previous task
            }
            catch (InterruptedException ex)
            {
                Thread.currentThread().interrupt();
            }
        }
     }

If  InterruptedException is thrown, so our thread goes into cycle and keep the lock on the ThreadPool object, so TaskManager-threads cannot notify that they became free as soon as they blocked on the ThreadPool. So if the interrupt was called when NO TaskManager-threads were free to execute the task, so the process just hangs.

There is a simple way to fix it. We need just to break the cycle if the process was interrupted and not to execute task like below.

    public synchronized void execute(WorkerTask task)
    {
       try
        {

           while (true)
           {
               // here we check if some TaskManager-thread is free to execute the task
               wait();// wait until some TaskManager-thread notify that it finished a previous task
           }
        catch (InterruptedException ex)
        {
           Thread.currentThread().interrupt();
        }

    }

Thanks,

Dmitrii Krendelev



________________________________
The information transmitted herein is intended only for the person or entity to which it is addressed and may contain confidential, proprietary and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.