Created
April 24, 2020 11:06
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UsedMemoryMonitor.java
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package org.dhatim.fastexcel; | |
import java.util.concurrent.CompletableFuture; | |
import static java.lang.String.format; | |
public class UsedMemoryMonitor<E extends Exception> { | |
volatile boolean stop = false; | |
volatile long maxUsedMemoryMB = 0; | |
public static <E extends Exception> long getMaxMemoryUsedDuring(VoidCallable<E> callable) throws E { | |
UsedMemoryMonitor monitor = new UsedMemoryMonitor(); | |
callable.call(); | |
monitor.stop = true; | |
return monitor.maxUsedMemoryMB; | |
} | |
private UsedMemoryMonitor() { | |
CompletableFuture.runAsync(() -> { | |
long initial = getRuntimeUsedMemoryMB(); | |
while (!stop) { | |
long used = getRuntimeUsedMemoryMB() - initial; | |
if(used > maxUsedMemoryMB){ | |
maxUsedMemoryMB = used; | |
System.out.println(format("max memory used %s MB", maxUsedMemoryMB)); | |
} | |
sleep(100); | |
} | |
}); | |
} | |
private static void sleep(int millis) { | |
try { | |
Thread.sleep(millis); | |
} catch (InterruptedException e) { | |
throw new RuntimeException(e); | |
} | |
} | |
private static long getRuntimeUsedMemoryMB() { | |
final long MEGABYTE = 1024L * 1024L; | |
Runtime runtime = Runtime.getRuntime(); | |
runtime.gc(); | |
return (runtime.totalMemory() - runtime.freeMemory()) / MEGABYTE; | |
} | |
@FunctionalInterface | |
interface VoidCallable<E extends Exception> { | |
void call() throws E; | |
} | |
} |
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