Heap and memory management is a facility provided by your C library (likely glibc). It maintains the heap and returns chunks of memory to you every time you do a malloc(). It doesn’t know heap size limit: every time you request more memory than what is available on the heap, it just goes and asks … Read more
There are lots of ways in which malloc/free can store the size of the memory area. For example, it might be stored just before the area returned by malloc. Or it might be stored in a lookup table elsewhere. Or it might be stored implicitly: some areas might be reserved for specific sizes of allocations. … Read more
My question is how to choose the min and max values, and the difference between the two (should max-min be small or big?) Short answer: don’t guess, profile your application. jconsole can give you useful high-level data such as a feeling for the main resident set vs. the transient data that we normally allocate and … Read more
When you set the VM budget on your emulator/device, what you are doing is telling the heap the maximum size it is allowed to be. At runtime, the heap grows dynamically in size as the Dalvik VM requests system memory from the operating system. The Dalvik VM typically starts by allocating a relatively small heap. … Read more
I’m sure this is a duplicate, but I’ll answer it anyway: If you are viewing Task Manager size, it will give you the size of the process. If there is no “pressure” (your system has plenty of memory available, and no process is being starved), it makes no sense to reduce a process’ virtual memory … Read more
Setting -Xmx to one gig doesn’t mean that the JVM will allocate that much memory upon start-up. The JVM will allocate only -Xms (plus overhead) until more heap space is needed. Do you need to protect your users from thrashing virtual memory or a failed memory allocation from the OS? If not, just set Xmx … Read more
I found the answer provided by greyfairer is wrong. The JVM runtime does not gather the root set from stack by looking at what bytecodes are used to push data on the stack. The stack frame consists of 4 byte(32bit arch) slots. Each slot could be a reference to a heap object or a primitive … Read more
Summary: your benchmark is flawed; just use a Vec (as described here), possibly with into_boxed_slice, as it is incredibly unlikely to be slower than a heap allocated array. Unfortunately, your benchmarks are flawed. First of all, you probably didn’t compile with optimizations (–release for cargo, -O for rustc). Because if you would have, the Rust … Read more
So long as you know what the semantics are, the only consequences of stack vs heap are in terms of making sure you don’t overflow the stack, and being aware that there’s a cost associated with garbage collecting the heap. For instance, the JIT could notice that a newly created object was never used outside … Read more
The Java Virtual Machine takes two command line arguments which set the initial and maximum heap sizes: -Xms and -Xmx. You can add a system environment variable named _JAVA_OPTIONS, and set the heap size values there. For example if you want a 512Mb initial and 1024Mb maximum heap size you could use: under Windows: SET … Read more