please have a look at this. http://www.reddit.com/comments/1jw6h7
seems dalvik is slower. 2014-05-11 22:28 GMT+08:00 Kristopher Micinski <[email protected]>: > First of all, this is just downright false, JS *will* be slower than > Java, but I'll address each of your points. > > On Sun, May 11, 2014 at 12:51 AM, 李白|字一日 <[email protected]> wrote: > > thanks for the reply. > > > > but i may think differently. > > > > javascript runtime can be shared, and no new memory allocation and memory > > copying required, only the apps require new memories when running. > > The Android runtime is also shared, common memory pages are mapped > between processes. This is the idea behind the "zygote" process, > which loads the VM in an initial process and then forks off new > processes, and due to copy on write (among other things) the VM is > never copied. > > Apps only require the new memory they need. You can't just slam them > all together in the same process, because that will completely destroy > security and that will never happen. By the way, the same thing > exists in JavaScript for multiple JavaScript tabs. > > but the android vm is not, at least you should allocation memory for > > inter-media code files like .class files. > > then allocate new memory for the vm and then allocate for the app. > > As I said, you don't allocate any new memory for the VM because of the > zygote. You have to allocate pages to keep track of the code, but you > also do this with JS, but it's way worse because you need extra stuff > to do all the data structures for interpretation / JIT. > > > for java multi-threading, you may need extra memory to providing more > stacks > > and extra execution on how to coordinating the threads. > > > > but javascript may need only one thread, and no threads switching > needed, it > > is event based. > > You'll still need threads in JavaScript to make anything efficient. > > webkit and javascript event model is native implemented (using c/c++) > and vm > > free, while java sdk is compiled in java code and interpreted to native. > > There are open source Java compilers. AOSP is open source. > > > html and javascript files are translated to native code or natived > > implemented interpretors when loaded. > > The same thing happens right now. > > > so i think java is by no means faster than javascript, especially when > you > > have very complicated interactions. > > It's up for debate, but your arguments for it don't show this. > > There are tricks to make this work, > http://en.wikipedia.org/wiki/Firefox_OS does them. > > However, JS doesn't have any inherent performance advantages over > Java: it's slower if implemented badly. > > > From all the above, i would like to say that javascript is easy and fast > to > > load and run, while java is slow to load and run. > > if that is true, i think that is the great performance gain. > > > > java server side is fast in that java programs have loaded and they are > all > > in memory and servers always provide large memory spaces, we can ignore > the > > loading and rebooting time it requires, but android is not for server > side > > programming, it may not have large memory space for too many apps and > users > > don't have patient to wait too long for starting a new app. > > Many apps are compiled natively or with a JIT, this is the exact same > as JavaScript. > > Kris > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > --- > You received this message because you are subscribed to a topic in the > Google Groups "Android Developers" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/android-developers/4UrtNOPympc/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/d/optout. > > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en --- You received this message because you are subscribed to the Google Groups "Android Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
