Measuring memory usage of a servlet, profiling advice?

Question

I have a servlet that receives xml data that is posted to this endpoint.

I convert the xml to a java object etc., and I want to make sure I am minimizing memory usage during this process.

What is the best way for me to analyze my memory usage and measure how things fluctuate as I post xml data to the servlet?

Answer 1

For tracing this always went well for me (output in console):

• -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps

2013-01-05T22:52:13.954+0100: 15918369.557: [GC 15918369.557: [DefNew: 65793K->227K(98304K), 0.0031220 secs] 235615K->170050K(491520K), 0.0033220 secs] [Times: user=0.01 sys=0.00, real=0.00 secs]

Reference: Virtual Machine Garbage Collection Tuning

Answer 2

VisualVM非常适合用来衡量您的应用程序，它提供了各种图表，用于显示运行时CPU信息，内存使用情况和线程等。

Answer 3

You can use JMX :

HeapMemory:

public String monitorMemory() {

    StringBuilder sb = new StringBuilder("Memory:");

    MemoryMXBean mmbean = ManagementFactory.getMemoryMXBean();
    MemoryUsage hmu = mmbean.getHeapMemoryUsage();
    sb.append("[HeapMemoryUsage:");
    sb.append(" Used=" + formatBytes(hmu.getUsed()));
    sb.append(" Committed=" + formatBytes(hmu.getCommitted()));
    sb.append("]");

    MemoryUsage nhmu = mmbean.getNonHeapMemoryUsage();
    sb.append("[NonHeapMemoryUsage:");
    sb.append(" Used=" + formatBytes(nhmu.getUsed()));
    sb.append(" Committed=" + formatBytes(nhmu.getCommitted()));
    sb.append("]");
    return sb.toString();
}

MemoryPool:

public String monitorMemoryPool() {
    StringBuilder sb = new StringBuilder("MemoryPool:");

    List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();

    for (MemoryPoolMXBean p : pools) {
        sb.append("[" + p.getName() + ":");
        MemoryUsage u = p.getUsage();
        sb.append(" Used=" + formatBytes(u.getUsed()));
        sb.append(" Committed=" + formatBytes(u.getCommitted()));
        sb.append("]");
    }
    return sb.toString();

}

Run the code above before and after you code or method.

This maybe not accurate enough while you web service process other requets.

As @Gavin Xiong said, you can use some tools with UI like VisualVM .

But, you'd better not use UI tools on you production environment.

Single Thread test will be more accurate.