memory – Page 50 – Tarik Billa

In Java, what is the best way to determine the size of an object?

September 9, 2022 by Tarik

You can use the java.lang.instrument package. Compile and put this class in a JAR: import java.lang.instrument.Instrumentation; public class ObjectSizeFetcher { private static Instrumentation instrumentation; public static void premain(String args, Instrumentation inst) { instrumentation = inst; } public static long getObjectSize(Object o) { return instrumentation.getObjectSize(o); } } Add the following to your MANIFEST.MF: Premain-Class: ObjectSizeFetcher Use … Read more

How to determine CPU and memory consumption from inside a process

September 8, 2022 by Tarik

Windows Some of the above values are easily available from the appropriate Win32 API, I just list them here for completeness. Others, however, need to be obtained from the Performance Data Helper library (PDH), which is a bit “unintuitive” and takes a lot of painful trial and error to get to work. (At least it … Read more

Fatal Error: Allowed Memory Size of 134217728 Bytes Exhausted (CodeIgniter + XML-RPC)

September 8, 2022 by Tarik

Changing the memory_limit by ini_set(‘memory_limit’, ‘-1′); is not a proper solution. Please don’t do that. Your PHP code may have a memory leak somewhere and you are telling the server to just use all the memory that it wants. You wouldn’t have fixed the problem at all. If you monitor your server, you will see … Read more

How do I discover memory usage of my application in Android?

September 7, 2022 by Tarik

Note that memory usage on modern operating systems like Linux is an extremely complicated and difficult to understand area. In fact the chances of you actually correctly interpreting whatever numbers you get is extremely low. (Pretty much every time I look at memory usage numbers with other engineers, there is always a long discussion about … Read more

How can I measure the actual memory usage of an application or process?

September 7, 2022 by Tarik

With ps or similar tools you will only get the amount of memory pages allocated by that process. This number is correct, but: does not reflect the actual amount of memory used by the application, only the amount of memory reserved for it can be misleading if pages are shared, for example by several threads … Read more

What is a “cache-friendly” code?

September 7, 2022 by Tarik

Preliminaries On modern computers, only the lowest level memory structures (the registers) can move data around in single clock cycles. However, registers are very expensive and most computer cores have less than a few dozen registers. At the other end of the memory spectrum (DRAM), the memory is very cheap (i.e. literally millions of times … Read more

How do I determine the size of an object in Python?

September 6, 2022 by Tarik

Just use the sys.getsizeof function defined in the sys module. sys.getsizeof(object[, default]): Return the size of an object in bytes. The object can be any type of object. All built-in objects will return correct results, but this does not have to hold true for third-party extensions as it is implementation specific. Only the memory consumption … Read more

How do I determine the size of my array in C?

August 29, 2022 by Tarik

Executive summary: int a[17]; size_t n = sizeof(a)/sizeof(a[0]); Full answer: To determine the size of your array in bytes, you can use the sizeof operator: int a[17]; size_t n = sizeof(a); On my computer, ints are 4 bytes long, so n is 68. To determine the number of elements in the array, we can divide … Read more

How can I create a memory leak in Java?

August 20, 2022 by Tarik

Here’s a good way to create a true memory leak (objects inaccessible by running code but still stored in memory) in pure Java: The application creates a long-running thread (or use a thread pool to leak even faster). The thread loads a class via an (optionally custom) ClassLoader. The class allocates a large chunk of … Read more