was宕機(jī)常見問題及參考解決方案-在線瀏覽
2025-07-23 19:42本頁面
【正文】 are started. 應(yīng)對策略：notify必須發(fā)生在所有wait之前。Synchronization is required for protecting some critical resources, but if large sections of code are synchronized, an application effectively will bee single threaded, and the throughput will decrease dramatically. To improve the performance, you should think about:1) Use other efficient algorithm to replace the monitor/lock?2) Try to keep the monitor lock for a short time?3) Reduce the number of threads using this monitor/lock?應(yīng)對策略：改變程序?qū)崿F(xiàn)算法，避免占用鎖時間過長。資源搶占死鎖（Dead Lock）線程運(yùn)行需要獲取到兩個資源，當(dāng)線程1獲取到資源A，線程2獲取到資源B，此時，線程1需要再獲取資源B，線程2需要再獲取資源A。其它想獲取到資源A或者資源B的線程必將都會掛起。二、CPU使用率高（High CPU Usage）:High CPU usage problem refer to that a system is performing poorly because of lack of CPU resources.A high CPU usage problem can occur when:1）Some threads consuming a lot of CUP resources2）A frequent GC probelm occurs程序自身耗用高CPU（比如：Infinite Loop）收集日志：生成JAVA CORE分析工具：操作系統(tǒng)監(jiān)控工具（比如TOPAS PS之類的） IBM Thread and Monitor Dump Analyzer應(yīng)對策略：調(diào)整程序，改變算法，使得最終耗用較少CPU資源。從而需要垃圾回收器去頻繁釋放很小的內(nèi)存空間。三、內(nèi)存溢出（Out Of Memory）:The JVM maintains two memory areas, the Java heap, and the native (or system) heap.These two heaps have different purposes, are maintained by different mechanisms, and are largely independent of each other. OutOfMemory condition that occurs could be due to either running out of Java heap or Native heap. 本地內(nèi)存溢出（Native OOM）收集日志：生成系統(tǒng)宕機(jī)日志（system dump） OS monitor tools, such as Svmon, top,vmstat and so on分析工具：（IBM Support Assistant）Dump Analyzer 應(yīng)對策略：暫時無。最終內(nèi)存被占滿。內(nèi)存泄漏（Java Memory Leak）當(dāng)你要用到公共的HASHMAP變量，不斷地往里ADD對象，但沒有remove操作。The Java heap bees exhausted when garbage collection cannot free enough objects to make a new object allocation. Garbage collection can free only objects that are no longer referenced by other objects, or referenced from the thread stacks.Java heap exhaustion can be identified from the Xverbosegc output w
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