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CountDownLatch-Runnable和Future-Callable
线程池
@Autowired private ThreadPoolTaskExecutor taskExecutor;CountDownLatch/Runnable
final int size = list.size(); final List<PaperDetail> details = new Vector(size); final CountDownLatch latch = new CountDownLatch(size); list.stream().forEach(paper -> taskExecutor.execute(() -> { details.add(getById(paper.getId())); latch.countDown(); })); try { latch.await(); } catch (InterruptedException e) { Logs.L().error("paper list error: ", e); throw new HNException("内部异常"); }Future/Callable
List<PaperDetail> details = Lists.newArrayList(); List<Future<PaperDetail>> futures = Lists.newArrayList(); list.forEach(paper -> futures.add(taskExecutor.submit(() -> getById(paper.getId())))); // 匿名有返回值的线程Callable for (int i = 0; i < futures.size(); i++) { try { details.add(futures.get(i).get(10, TimeUnit.SECONDS)); } catch (Exception e) { Logs.L().error("paper list error: ", e); } }
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golang基于master/worker模式的高并发
master调度
type Master struct { maxWorkers int workerPool chan chan Job } func NewMaster(maxWorkers int) *Master { return &Master{ maxWorkers: maxWorkers, workerPool: make(chan chan Job, maxWorkers), } } func (m *Master) dispatch() { for i := 1; i < m.maxWorkers+1; i++ { worker := NewWorker(i, m.workerPool) worker.Run() } go func() { for { select { case job := <-JobQueue: go func(job Job) { jobChannel := <-m.workerPool jobChannel <- job }(job) } } }() }job
var ( MaxWorkers = 100 JobQueueLen = 100 JobQueue = make(chan Job, JobQueueLen) ) type Job struct { Payload Payload } type Payload struct { Name string } func (p *Payload) Do(id int) { fmt.Printf("worker-%v now working, job: %v\n", id, p.Name) time.Sleep(time.Second * 5) }worker
type Worker struct { Id int quit chan bool jobChannel chan Job workerPool chan chan Job } func NewWorker(id int, workerPool chan chan Job) Worker { return Worker{ Id: id, quit: make(chan bool), jobChannel: make(chan Job), workerPool: workerPool, } } func (w *Worker) Run() { go func() { for { w.workerPool <- w.jobChannel select { case job := <-w.jobChannel: job.Payload.Do(w.Id) case <-w.quit: return } } }() } func (w *Worker) Stop() { go func() { w.quit <- true }() }main
func main() { master := NewMaster(MaxWorkers) master.dispatch() for i := 1; i <= 100000; i++ { JobQueue <- Job{Payload: Payload{Name: fmt.Sprintf("Job%v", i)}} } time.Sleep(time.Second * 1000) }
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Spring线程池、异步执行Future、Callable
引入依赖
<dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${springframework-version}</version> </dependency>spring bean
<bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor"> <property name="corePoolSize" value="10"/> <property name="keepAliveSeconds" value="200"/> <property name="maxPoolSize" value="50"/> </bean>注入线程池
@Autowired private ThreadPoolTaskExecutor taskExecutor;执行
List<T> taskList = Lists.newArrayList(); //任务列表 List<T> resultList = Lists.newArrayList(); //执行结果列表 List<Future<T>> futures = Lists.newArrayList(); //异步计算列表 taskList.forEach(task -> futures.add(taskExecutor.submit(() -> {process task...}))); // ()->: 匿名有返回值的线程Callable for (int i = 0; i < futures.size(); i++) { try { resultList.add(futures.get(i).get(10, TimeUnit.SECONDS)); //超时设置 } catch (Exception e) { log.error("process error: ", e); } }
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生产环境中tomcat启动非常缓慢
现象
生产环境(centos7,jdk8)中tomcat启动非常缓慢，几分钟才能启动
解决
- 方式1：修改%JRE_HOME%/lib/security/java.security文件：
修改前：securerandom.source=file:/dev/random 修改后：securerandom.source=file:/dev/./urandom - 方式二：追加java启动参数
$JAVA_OPTS -Djava.security.egd=file:/dev/./urandom
原因分析
关键字
- tomcat启动优化
- tomcat的
sessionId及其它随机数的生成, 通过java.security.SecureRandom生成随机数来实现，随机数算法使用的是SHA1PRNG /dev/random, 阻塞的随机数发生器/dev/urandom, 非阻塞的随机数发生器- 伪随机数发生器：
- 熵池
- 密码安全学
参考
- 参考1：https://wiki.apache.org/tomcat/HowTo/FasterStartUp
- 参考2：http://hongjiang.info/jvm-random-and-entropy-source/
扩展：linux生成随机数
cat /dev/urandom | head -n 10 | md5sum | head -c 10 #c61adce3e4 cat /dev/urandom | strings -n 8 | head -n 1 #生成全字符的随机字符串，fLqF!lSB) cat /dev/urandom | sed -e 's/[^a-zA-Z0-9]//g' | strings -n 8 | head -n 1 #生成数字加字母的随机字符串，HRZuXFMb 其中 strings -n设置字符串的字符数，head -n设置输出的行数
- 方式1：修改%JRE_HOME%/lib/security/java.security文件：
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golang计算上传的文件大小
如题，直接上代码
// 获取文件大小的接口 type Size interface { Size() int64 } // 获取文件信息的接口 type Stat interface { Stat() (os.FileInfo, error) } // 文件大小 var size int64 = 0 if stat, ok := file.(Stat); ok { fileInfo, err := stat.Stat() if err != nil { panic(err) } size = fileInfo.Size() } else if sizer, ok := file.(Size); ok { size = sizer.Size() }
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修改github的push方式
现象
github每次push的时候，都要输入用户名密码
解决：将push方式由https方式修改为git方式
git remote -v git remote rm origin git remote add origin git@github.com:xxx/xxx.git git push origin
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