How to determine the amount of memory needed to run a thread?

The amount of memory required to run a single thread in Java depends on several factors, including JVM settings and the platform. The main parameter is the thread's stack size.

By default, the stack size for each thread is set by the JVM parameter -Xss. For example, it is often 1 MB per thread by default, but this can vary.

To determine or set the stack size for a thread, you can use:

java -Xss512k MyApp

where 512k is the stack size in kilobytes.

The total memory per thread includes:

• Thread stack — for storing local variables, method calls, etc.
• Heap — the shared memory area for objects accessible to all threads.

To estimate the memory needed to start a thread, consider the stack size and JVM overhead. If many threads are needed, the stack size is often reduced to avoid exhausting memory.

Example of creating a thread with memory considerations:

Thread thread = new Thread(() -> {
    // thread code
});
thread.start();

The stack size is set at JVM startup, not when creating the thread in code.