jdk1 8執行緒池 基於原始碼了解工作流程

構造方法

public

threadpoolexecutor
(int corepoolsize,
int maximumpoolsize,
long keepalivetime,
timeunit unit,
blockingqueue
workqueue,
threadfactory threadfactory,
rejectedexecutionhandler handler)

public

void
execute
(runnable command)
// 當前執行緒數量大於核心執行緒數量if(
isrunning
(c)&& workqueue.
offer
(command)
)// 佇列滿了
elseif(
!addworker
(command,
false))
// 新建執行緒執行(執行緒數量邊界為 maximumpoolsize)
reject
(command)
;// 執行緒數量達到 maximumpoolsize， 等待佇列滿了，執行拒絕策略
}

private

boolean
addworker
(runnable firsttask,
boolean core)
}boolean workerstarted =
false
;boolean workeradded =
false
; worker w = null;
try}
finally
if(workeradded)}}
finally
return workerstarted;
}

private

final
class
worker
extends
abstractqueuedsynchronizer
implements
runnable
/** delegates main run loop to outer runworker */
public
void
run(
)

final

void
runworker
(worker w)
catch
(runtimeexception x)
catch
(error x)
catch
(throwable x)
finally
}finally
} completedabruptly =
false;}
finally
}

private runnable gettask()

int wc =
workercountof
(c);
// are workers subject to culling?
boolean timed = allowcorethreadtimeout || wc > corepoolsize;
// 根據是否允許核心執行緒死亡或者當前執行緒數大於了核心執行緒數if(
(wc > maximumpoolsize ||
(timed && timedout))&&
(wc >
1|| workqueue.
isempty()
))trycatch
(interruptedexception retry)
}}

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