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How can I initialize a double variable to infinity

纵然是瞬间 提交于 2020-02-29 19:44:59
Q. How can I initialize a double variable to infinity? A. Java has built-in constants available for this purpose: Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY. Q. Can you compare a double to an int? A. Not without doing a type conversion, but remember that Java usually does the requisite type conversion automatically. For example, if x is an int with the value 3, then the expression (x < 3.1) is true—Java converts x to double (because 3.1 is a double literal) before performing the comparison. Q. What are the values of 1/0 and 1.0/0.0 as Java expressions? A. The first generates a

XEN4.0 && KVM性能稳定性测试

一笑奈何 提交于 2019-12-02 20:52:46
初始测试xen和kvm两款虚拟机软件的稳定性及性能。 为了测试虚拟机运行时在宿主机上的瓶颈,需要同时在同一台宿主机上面根据业务需求启动尽量多的虚拟机,以便观察资源的分配调度情况,根据我们宿主机的情况,每台宿主机适合分配两台2CPU+4G MEM的虚拟机。所有类型的虚拟机均未做优化,xen和kvm均采用全虚拟化。 测试环境 XEN环境 宿主机参数 机器型号:PowerEdge R710 CPU型号:Intel(R) Xeon(R) CPU E5504 @ 2.00GHz * 4 MEM大小:4096 MB * 4 RAID模式:RAID5+hot DISK大小:60G / + LVM 816.75 GB 操作系统:Debian6 最小化安装+必要的虚拟化环境 内核版本:XEN-4.0 2.6.32-5-xen-amd64 x86_64 文件系统类型:ext3 虚拟机环境 虚拟机名称:xen6 CPU型号:Intel(R) Xeon(R) CPU E5504 @ 2.00GHz * 2 MEM大小:4113384KB (4016MB) DISK大小:30GB / + 2GB swap + 10GB home 文件系统类型:ext4 内核版本:2.6.32-5-amd64 x86_64 信息如下图: 虚拟机名称:xen7 CPU型号:Intel(R) Xeon(R) CPU E5504