java - The blocking queue of the thread pool is not full, but a rejection exception is thrown - Stack Overflow

admin管理员组

文章数量:1434381

My thread pool throws rejection exception when it is not full Thread pool parameter settings:

1. corePoolSize：1024
2. maximumPoolSize：1024
3. workQueue：LinkedBlockingQueue
4. queueSize：1024
5. RejectedExecutionHandler：throw RejectedExecutionException Exception：

Thread pool is EXHAUSTED! Thread Name: xxx, Pool Size: 1024 (active: 93, core: 1024, max: 1024, largest: 1024), Task: 10414879419 (completed: 10414878332), Executor status:(isShutdown:false, isTerminated:false, isTerminating:false, queue:[{}])

Rejection exception thrown during thread pool operation. However, the thread pool monitoring panel and exception logs show that the number of core threads and the blocking queue length of the thread pool are both less than 100.

The exception is thrown at line 1355. It seems that adding a new task to the blocking queue failed. However, the size of the blocking queue at this time is less than 100, and the capacity is 1024. Why does calling the offer() method fail?

    public void execute(Runnable command) {
        if (command == null)
            throw new NullPointerException();
        /*
         * Proceed in 3 steps:
         *
         * 1. If fewer than corePoolSize threads are running, try to
         * start a new thread with the given command as its first
         * task.  The call to addWorker atomically checks runState and
         * workerCount, and so prevents false alarms that would add
         * threads when it shouldn't, by returning false.
         *
         * 2. If a task can be successfully queued, then we still need
         * to double-check whether we should have added a thread
         * (because existing ones died since last checking) or that
         * the pool shut down since entry into this method. So we
         * recheck state and if necessary roll back the enqueuing if
         * stopped, or start a new thread if there are none.
         *
         * 3. If we cannot queue task, then we try to add a new
         * thread.  If it fails, we know we are shut down or saturated
         * and so reject the task.
         */
        int c = ctl.get();
        if (workerCountOf(c) < corePoolSize) {
            if (addWorker(command, true))
                return;
            c = ctl.get();
        }
        if (isRunning(c) && workQueue.offer(command)) {
            int recheck = ctl.get();
            if (! isRunning(recheck) && remove(command))
                reject(command);
            else if (workerCountOf(recheck) == 0)
                addWorker(null, false);
        }
        else if (!addWorker(command, false))
            reject(command);
    }

Why does the thread pool blocking queue throw a rejection exception when it is not full?

Why does the offer() method return false when the blocking queue is not full?

本文标签：