java.lang.Object
java.util.concurrent.ThreadPoolExecutor.DiscardOldestPolicy
- All Implemented Interfaces:
RejectedExecutionHandler
- Enclosing class:
ThreadPoolExecutor
public static class ThreadPoolExecutor.DiscardOldestPolicy
extends Object
implements RejectedExecutionHandler
A handler for rejected tasks that discards the oldest unhandled
request and then retries
execute
, unless the executor
is shut down, in which case the task is discarded. This policy is
rarely useful in cases where other threads may be waiting for
tasks to terminate, or failures must be recorded. Instead consider
using a handler of the form:
new RejectedExecutionHandler() {
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
Runnable dropped = e.getQueue().poll();
if (dropped instanceof Future<?>) {
((Future<?>)dropped).cancel(false);
// also consider logging the failure
}
e.execute(r); // retry
}}
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Obtains and ignores the next task that the executor would otherwise execute, if one is immediately available, and then retries execution of task r, unless the executor is shut down, in which case task r is instead discarded.
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Constructor Details
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DiscardOldestPolicy
public DiscardOldestPolicy()Creates aDiscardOldestPolicy
for the given executor.
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Method Details
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rejectedExecution
Obtains and ignores the next task that the executor would otherwise execute, if one is immediately available, and then retries execution of task r, unless the executor is shut down, in which case task r is instead discarded.- Specified by:
rejectedExecution
in interfaceRejectedExecutionHandler
- Parameters:
r
- the runnable task requested to be executede
- the executor attempting to execute this task
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