android application，Dalvik virtual machine和进程关系

              Every Android application runs in a Dalvik virtual machine instances where each instance of a virtual machine is a separate process space. Virtual machine thread mechanism, memory allocation and management, Mutex, etc. are all dependent on the underlying operating system and achieve. All Android application thread corresponds to a Linux thread, the virtual machine and thus can be more dependent on the operating system thread scheduling and management mechanism.

        Different applications in different process space to run, combined with the application of different sources are using a different user to run Linux, you can apply the greatest degree of protection of security and independence of operation.

        Zygote is a virtual machine process, but also an incubator for virtual machine instance, whenever the system requirements for the implementation of an Android application, Zygote would FORK a child process to execute the application. Benefits of doing so is obvious: Zygote process is generated when the system starts, it will complete the initialization of the virtual machine, library loading, the preset library loading and initialization, etc. operations, while in the system needs a new virtual machine instance, Zygote by copying itself, the fastest delivery of systems. In addition, for some read-only system libraries, all virtual machine instances, and Zygote share a memory region, considerable savings in memory overhead.