multithreading vs concurrency in java

you create a Countdownlatch object, the object uses the constructor's parameters to initialize the internal counter. Each time the countdown () method is called, the internal counter of the Countdownlatch object is reduced by one. When the internal counter reaches 0, the Countdownlatch object wakes up all the threads that use the await () method to sleep.It is not possible to reinitialize or modify the value of the internal counter of the Countdownlatch object. Once the value of the counter is

(); If the element is not empty else {//Gets the delay time long delay = First.getdelay (nanoseconds); If the delay time is reached, return and remove the team first element if (delay Poll method with timeout (important): /** * Gets and removes the first element of the team, the method blocks until the queue contains an element that reaches the delay time or times out * * @return The first element of the team, or null * @throws interruptedexception block

,controlcinema2;public Cinema () {controlCinema1 = new object (); controlCinema2 = new Object (); VACANCIESCINEMA1 = 20;vacanciescinema2 = 20;} public boolean sellTickets1 (int number) {synchronized (CONTROLCINEMA1) {if (number Package Chapter2;public class TicketOffice1 implements Runnable{private cinema cinema;public TicketOffice1 (cinema Cinema) {This.cinema = cinema;} @Overridepublic void Run () {cinema.selltickets1 (3); Cinema.selltickets1 (2); cinema.selltickets2 (2); Cinema.returntickets1

+" Seconds! "); //wait for other threads to executebarrier.await (); Doing ("I'm ready, the current time is:" +System.currenttimemillis ()); } Catch(interruptedexception e) {e.printstacktrace (); } Catch(brokenbarrierexception e) {e.printstacktrace (); }}},child). Start (); } } /*** @Description: Print the name of the outgoing thread *@parammsg * @returType: void*/ Public Static voiddoing (String msg) {System.out.println (Thread.CurrentThread (). GetName ()+":"+msg); }}Multi-thr

Multithreading concurrent programming is an important piece of Java programming, is also the focus of the interview area, or it is worth in-depth studyConcept:1 Threads: Execution units in a process responsible for program executionThe thread itself relies on the program to runThreads are sequential control flows in a program and can only use resources and environments that are assigned to programs2 process: Executing the programA process contains at

. Repeat this process until a valid node is deleted. Returns null if the queue has not been deleted successfully after traversing. The following figure is a successful deletion of the structure diagram: from the above figure, we can see that, during the delete operation, the head over the number of nodes reached the threshold, triggering the executive head of the update, so that it points to the C node. After removing the header node from above, the two schematic diagram shows that the queue

the length expands, the hash rules change as well. Let's review the hash formula:index = hashcode (Key) (Length-1) When the original array length is 8 o'clock, the hash operation is done with the 111B (representing the binary 7), and the new array length is 16,hash and 1111B (representing the binary 15). hash results are obviously different . The Java code for rehash is as follows: /** * Transfers all entries from the current table to newtable.

daemon thread is an infinite loop to wait for a service request or to perform a thread's task. They cannot do important work because it is impossible to know when the daemon will be able to get the CPU time slice, and when no other thread is running, the daemon thread may end at any time. A typical daemon thread is the Java garbage collector (garbage Collector).Vii. Grouping of threadsJava provides a Threadgroup class that represents a set of threads

in the past single-core CPU era, single-tasking can only execute a single program at a time point, with the development of multicore CPUs, parallel program development is particularly important. "Practical Java High concurrency Program design" mainly introduces the basis of Java-based parallel programming, ideas, methods and actual combat. First, based on the Con

, or a timeout parameter can be taken in the join method. Calls to the join () method can be interrupted and calls to the interrupt () method on the calling thread .Two shared restricted resources1. Sharing resources 2. Changes are involved 3. Multiple threads usingBasically, all concurrency patterns are used to serialize access to shared resources when resolving thread-conflict problems-that is, only one thread is allowed to access the shared resourc

this process, thread B gets to the value of n is an old value, although equal to the current value of N, but actually the value of n has undergone a change of 1 to 2 to 1The above example is a typical ABA problem.How to solve the ABA problemAdd a version number to the variable, and compare the value of the current variable to compare the version number of the current variable. Atomicstampedreference in Java solves this problem. Long cycle times c

Personally, I don't have a lot of high concurrency in my job, the reason is because I work in the company most of the content is related to the business, accurately, most of the management system so for concurrent cognition and mastery is not much, the reason to master this content is because in the interview is often asked (although not), And see the big God sent a treasure of recruitment information, feel this aspect is very important. (Hangzhou) Se

to a copy on write collection. Several readers can retrieve elements from the map concurrently in a lock-free fashion.Write Concurrency:Better concurrency than the copy on write collections This basically serialize updates (one update at a time). Using A concurrent hash map you have a good chance of doing several updates concurrently. If your hash keys is evenly distributed.If you don't want to having the effect of a copy on write map, you can always

components simply to implement a custom method, and then add Aqs provided template method, you can implement a powerful custom synchronization components, So after reading the following four blog posts, Reentrantlock is really a piece of cake to understand. A brief introduction to the Aqs:aqs of "-–j.u.c java concurrency" "Dead java

"Practical Java High Concurrency Programming 1" Pointers in Java: unsafe class"Practical Java High Concurrency Programming 2" lock-free object reference: Atomicreference"Practical Java High Co