Threading Learning--(vi) Single and multithreaded, ThreadLocal

First, ThreadLocal

With thread safety implemented using the WAIT/NOTIFY approach, performance will be greatly impacted. The solution is to use space for time and thread safety without locking.

To take a look at a small example, set in the thread, get is threadlocal

 Packagethread2; Public classconnthreadlocal { Public Staticthreadlocal<string> th =NewThreadlocal<string>();  Public voidsetth (String value) {Th.set (value); }     Public voidGetth () {System.out.println (Thread.CurrentThread (). GetName ()+ ":" + This. Th.get ()); }         Public Static voidMain (string[] args)throwsinterruptedexception {Finalconnthreadlocal ct =Newconnthreadlocal (); Thread T1=NewThread (NewRunnable () {@Override Public voidrun () {CT.SETTH ("ABC");            CT.GETTH (); }        }, "T1"); Thread T2=NewThread (NewRunnable () {@Override Public voidrun () {Try{Thread.Sleep (1000);                CT.GETTH (); } Catch(interruptedexception e) {e.printstacktrace (); }            }        }, "T2");        T1.start ();    T2.start (); }    }

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Second, single and multi-threaded

The Singleton has a hunger pattern and lazy mode, but these two modes are not available in multithreaded situations. Consideration of new and thread-safe issues in multi-threading generally consider two ways of double check instance and static inner class to implement singleton mode.

Static inner class mode:

 Package bhz.base.conn011;  Public class singletion {        privatestaticclass  innersingletion {          Privatestaticnew  singletion ();    }          Public Static singletion getinstance () {        return  innersingletion.single;    }    }

Double check instance mode:

 Packagethread2; Public classDubblesingleton {Private StaticDubblesingleton ds;  Public  StaticDubblesingleton Getds () {if(ds = =NULL){            synchronized(Dubblesingleton.class) {                if(ds = =NULL) {DS=NewDubblesingleton (); }            }        }        returnds; }         Public Static voidMain (string[] args) {Thread T1=NewThread (NewRunnable () {@Override Public voidrun () {System.out.println (Dubblesingleton.getds (). Hashcode ()); }        },"T1"); Thread T2=NewThread (NewRunnable () {@Override Public voidrun () {System.out.println (Dubblesingleton.getds (). Hashcode ()); }        },"T2"); Thread T3=NewThread (NewRunnable () {@Override Public voidrun () {System.out.println (Dubblesingleton.getds (). Hashcode ()); }        },"T3");        T1.start ();        T2.start ();    T3.start (); }    }

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Threading Learning--(vi) Single and multithreaded, ThreadLocal