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python自学成才之路 死锁的解决方案

该线程需要获取的锁按照id做一个排序 locks = sorted(locks, key=lambda x: id(x)) # 确保这些锁获取是有序的,如果出现无序则抛出异常 acquired = getattr(_local,'acquired',[]) if acquired and max(id(lock) for lock in acquired) >= id(locks[0 ]): raise RuntimeError('Lock Order Violation') # 将获取到的锁放到线程本地对象上 acquired.extend(locks ) _local.acquired = acquired try: for lock in locks: lock.acquire() 第二个不好理解的地方是acquired = getattr(_local,‘acquired’,[])这段代码,这段代码的意思是获取线程本地对象的acquired这个属性,如果没有这个属性则创建一个这样的属性

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聊聊rocketmq的RemotingSendRequestException

= this.semaphoreAsync.tryAcquire(timeoutMillis, TimeUnit.MILLISECONDS); if (acquired) { new RemotingTimeoutException(info); } } } ​ //...... } invokeAsyncImpl在acquired = this.semaphoreOneway.tryAcquire(timeoutMillis, TimeUnit.MILLISECONDS); if (acquired) { new RemotingTimeoutException(info); } } } ​ //...... } invokeOnewayImpl在acquired 为true,channel.writeAndFlush(request)抛出异常时,会将异常转为RemotingSendRequestException;invokeOnewayImpl在acquired

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    python库之_thread

    integer waitflag argument is present, the action depends on its value: if it is zero, the lock is only acquired if it can be acquired immediately without waiting, while if it is nonzero, the lock is acquired unconditionally The return value is True if the lock is acquired successfully, False if not. (11)lock.release() (12)lock.locked

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    聊聊rocketmq的RemotingSendRequestException

    = this.semaphoreAsync.tryAcquire(timeoutMillis, TimeUnit.MILLISECONDS); if (acquired) { throw new RemotingTimeoutException(info); } } } //...... } invokeAsyncImpl在acquired = this.semaphoreOneway.tryAcquire(timeoutMillis, TimeUnit.MILLISECONDS); if (acquired) { new RemotingTimeoutException(info); } } } //...... } invokeOnewayImpl在acquired 为true,channel.writeAndFlush(request)抛出异常时,会将异常转为RemotingSendRequestException;invokeOnewayImpl在acquired

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    使用python实现可重入的公平读写锁

    <Reader(Thread-2, started 140256742565632)> start <Reader(Thread-2, started 140256742565632)> acquired <Writer(Thread-6, started 140256753055488)> stop <Writer(Thread-7, started 140256742565632)> acquired <Writer(Thread-7, started 140256742565632)> stop <Writer(Thread-8, started 140256498145024)> acquired <Writer(Thread-8, started 140256498145024)> stop <Writer(Thread-9, started 140256487655168)> acquired <Writer(Thread-9, started 140256487655168)> stop <Writer(Thread-10, started 140256477165312)> acquired

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    Python多进程编程

    结果(输出文件) Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lockd acquired via with Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly Lock acquired directly 回到顶部 3.

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    Microservices Ecosystem Transit Map

    Vendor Stations: PubNub Blocks Joyent Manta Functions (acquired by Samsung) Hook.io Webtask Iron.io LSQ Mashery (acquired) CA* API Management (acquired Layer7) RedHat* 3Scale (acquired) Tyk* Oracle** API Management Mulesoft** API Manager IBM* API Connect Google Apigee (acquired) Amazon Web Services* API Gateway Microsoft* Azure API Management (acquired Apiphany) Mashape* Kong APinf* ————————— District: Vendor Stations: APIHound APIs.io ProgammableWeb (acquired by MuleSoft) API Harmony (an IBM project)

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    基于Consul的分布式信号量实现

    实现思路 - 信号量存储:semaphore/key - acquired操作: - 创建session - 锁定key竞争者:semaphore/key/session - 查询信号量 - 如果持有者已达上限,返回false,如果阻塞模式,就继续尝试acquired操作 - 如果持有者未达上限,更新semaphore/key/.lock的内容,将当前线程的sessionId加入到holders 如果没有更新成功,说明有其他竞争者抢占了资源,返回false,阻塞模式下继续尝试acquired操作 - release操作: - 从semaphore/key/.lock的holders中移除当前 { if(acquired) { logger.error(sessionId + " - Already acquired"); throw new RuntimeException(sessionId + " - Already acquired"); } // create session

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    七日Python之路--第四天(之多线程)

    integerwaitflag argument is present, the action depends on its value: if it is zero, the lock is only acquired if it can be acquired immediately without waiting, while if it is nonzero, the lock is acquired The return value is True if the lock is acquired successfully, False if not. lock.release() Releases The lock must have been acquired earlier, but not necessarily by the same thread. lock.locked() Return the status of the lock: True if it has been acquired by some thread,False if not. ---- 关于线程的知识点比较多

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    python多线程-Semaphore(

    print('{0} is waiting semaphore.'.format(self.name)) sem.acquire() print('{0} acquired Thread-0 acquired semaphore(Thu Oct 25 20:33:18 2018). Thread-1 is waiting semaphore. Thread-1 acquired semaphore(Thu Oct 25 20:33:18 2018). Thread-2 is waiting semaphore. Thread-2 acquired semaphore(Thu Oct 25 20:33:18 2018). Thread-3 is waiting semaphore. Thread-3 acquired semaphore(Thu Oct 25 20:33:23 2018). Thread-1 release semaphore.

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    简单聊聊Glide的内存缓存

    EngineResource是将资源进行封装的一个类,它有一个计数acquired,记录资源被引用的次数,当资源被取出使用时+1(acquired函数),当资源被释放时-1(release函数)。 当acquired为0时,会将它从ActiveResources中移除,存入LruCache。 代码如下: void release() { synchronized (listener) { synchronized (this) { if (acquired <= 0) { throw new IllegalStateException("Cannot release a recycled or not yet acquired resource"); release何时执行 上面我们知道当资源被使用时会调用EngineResource的acquired函数,释放的时候会调用EngineResource的release函数。

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    利用LockSupport实现互斥锁和共享锁

    waitThreadsQueue.add(currentThread); if (maxWaitInMills > 0) { boolean acquired tryAcquire(1)) { threadOwnsTheLock = currentThread; acquired left); cost = mark - System.nanoTime(); } return acquired (1)) { threadsOwnsLock.add(Thread.currentThread()); acquired - System.nanoTime(); //有可能是被唤醒重新去获取锁,没获取到还得继续等待剩下的时间(并不精确) } return acquired

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    Redission分布式锁加锁原理源码解析

    becomes * disabled for thread scheduling purposes and lies dormant until the * lock has been acquired * * If the lock is acquired, it is held until unlock is invoked, * or until Thread.currentThread().getId(); Long ttl = tryAcquire(leaseTime, unit, threadId); // lock acquired while (true) { ttl = tryAcquire(leaseTime, unit, threadId); // lock acquired return; } Long ttlRemaining = future.getNow(); // lock acquired

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    jdk7 AbstractQueuedSynchronizer(AQS) 应用分析

    and lies dormant until one of two things happens: * *

    * *

    If the lock is acquired by the current thread then the lock hold * * @return {@code true} if the lock was free and was acquired by the * current lock has been set to use a fair ordering policy then * an available lock will not be acquired * *

  • The specified waiting time elapses * * * *

    If the lock is acquired

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  • python库之threading

    Once a thread has acquired it, subsequent attempts to acquire it block, until it is released; any thread A reentrant lock must be released by the thread that acquired it. Once a thread has acquired a reentrant lock, the same thread may acquire it again without blocking; the thread must release it once for each time it has acquired it.See RLock Objects. (9)threading.Semaphore

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    Python | 多线程死锁问题的巧妙解决方法

    # 对锁按照id进行排序 locks = sorted(locks, key=lambda x: id(x)) # 如果已经持有锁当中的序号有比当前更大的,说明策略失败 acquired = getattr(_local,'acquired',[]) if acquired and max(id(lock) for lock in acquired) >= id(locks[0 ]): raise RuntimeError('Lock Order Violation') # 获取所有锁 acquired.extend(locks) _local.acquired = acquired try: for lock in locks: lock.acquire() yield finally : # 倒叙释放 for lock in reversed(locks): lock.release() del acquired

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    线上疑难定位:trying to use a recycled bitmap - 下

    com.bumptech.glide.load.engine.EngineResource#release void release() { boolean release = false; synchronized (this) { if (acquired <= 0) { throw new IllegalStateException("Cannot release a recycled or not yet acquired resource "); } if (--acquired == 0) { release = true; } } if (release) { listener.onResourceReleased(key, this); } } 这里的acquired,其实是判断,其他页面有没有也在加载这个图片,如果都没有了,才会进入内存缓存

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    C# 值类型的局限性

    class Counter { private int _i; public int Increment() { bool acquired = false; try { Monitor.Enter(_i, ref acquired); return ++_i; } finally { if (acquired) Monitor.Exit

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    Quartz分布式调度存在的性能问题分析

    秒内需要调度的任务(job下次执行时间在30秒内),根据执行时间排序(在数据库查询时排序),最后释放分布式锁(LOCK_TRIGGER_ACCESS); 在获取job时,会将状态由WAITING更新为ACQUIRED EXECUTING状态,如果修改成功,则更新cron下一次执行时间以及状态恢复为WAITING,最后释放分布式锁(LOCK_TRIGGER_ACCESS); 5、for遍历执行这一批次job,第(4)步将Job状态由ACQUIRED 假设只部署一个节点,且maxBatchSize最大为1,即不考虑分布式锁、不考虑批量的情况,那么quartz的调度流程可以简化为: 1、查询数据库,获取需要调度的job,并更新job的状态,由WAITING更新为ACQUIRED ; 2、更新job状态,由ACQUIRED改为EXECUTING状态,如果修改成功,则更新cron下一次执行时间以及状态恢复为WAITING; 3、如果第(2)步成功,则获取线程池,将Job放入线程池, 分布式调度下的故障恢复流程: 定时每clusterCheckinInterval毫秒检测掉线的节点; 如果有节点掉线,加分布式锁(LOCK_TRIGGER_ACCESS),获取掉线的节点的调度记录; 如果调度状态为ACQUIRED

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    Python3 与 C# 并发编程之~ 线程篇3

    contextmanagerdef acquire(*args): # 以id将锁进行排序 args = sorted(args, key=lambda x: id(x)) # 确保不违反以前获取的锁顺序 acquired = getattr(_local, 'acquired', []) if acquired and max(id(lock) for lock in acquired) >= id(args[0 ]): raise RuntimeError('锁顺序有问题') # 获取所有锁 acquired.extend(args) _local.acquired = acquired # ThreadLocal:每个线程独享acquired # 固定格式 try: for lock in args: lock.acquire() 逆向释放锁资源 for lock in reversed(args): lock.release() # 把释放掉的锁给删了 del acquired

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