开篇

 StacktraceCollectorProfiler主要用来采集线程的调用栈，原理是通过ManagementFactory.getThreadMXBean()返回的ThreadMXBean对象来实现。

源码分析

public void profile() {        // 获取此刻所有线程的dump信息        ThreadInfo[] threadInfos = threadMXBean.dumpAllThreads(false, false);        if (threadInfos == null) {            return;        }                // 遍历线程信息并处理每个线程        for (ThreadInfo threadInfo : threadInfos) {            String threadName = threadInfo.getThreadName();            if (threadName == null) {                threadName = "";            }                        if (!ignoreThreadNamePrefix.isEmpty()                    && threadName.startsWith(ignoreThreadNamePrefix)) {                continue;            }                        // 获取线程的调用栈            StackTraceElement[] stackTraceElements = threadInfo.getStackTrace();            // 创建调用栈对象            Stacktrace stacktrace = new Stacktrace();            stacktrace.setThreadName(threadName);            stacktrace.setThreadState(String.valueOf(threadInfo.getThreadState()));            // 创建保存调用栈的list            int totalLength = 0;            List
     
       stack = new ArrayList<>(stackTraceElements.length);            // 按照倒序保存调用链，最底层的放在最前面，把最根本的原因发在前面            for (int i = stackTraceElements.length - 1; i >= 0; i--) {                StackTraceElement stackTraceElement = stackTraceElements[i];                String className = String.valueOf(stackTraceElement.getClassName());                String methodName = String.valueOf(stackTraceElement.getMethodName());                stack.add(new ClassAndMethod(className, methodName));                totalLength += className.length() + methodName.length();                // 如果长度超出限制，那么就截断                if (totalLength >= Constants.MAX_STRING_LENGTH) {                    stack.add(new ClassAndMethod("_stack_", "_trimmed_"));                    break;                }            }                        // 反转调用链，把最底层的放在最前面。            ClassAndMethod[] classAndMethodArray = new ClassAndMethod[stack.size()];            for (int i = 0; i < stack.size(); i++) {                classAndMethodArray[classAndMethodArray.length - 1 - i] = stack.get(i);            }                        stacktrace.setStack(classAndMethodArray);                        buffer.appendValue(stacktrace);        }    }
     

采集结果

调用链的反向序列为：

• java.lang.Thread.sleep
• com.uber.profiling.examples.HelloWorldApplication.privateSleepMethod
• com.uber.profiling.examples.HelloWorldApplication.main

{    "stacktrace": ["java.lang.Thread.sleep", "com.uber.profiling.examples.HelloWorldApplication.privateSleepMethod", "com.uber.profiling.examples.HelloWorldApplication.main"],    "endEpoch": 1536072801080,    "appId": null,    "host": "xiaozhideMacBook-Pro.local",    "name": "2203@xiaozhideMacBook-Pro.local",    "processUuid": "1e580f6e-0493-4e5b-bee2-a61c5f7b097d",    "threadState": "TIMED_WAITING",    "count": 24,    "tag": "mytag",    "startEpoch": 1536072796084,    "threadName": "main"}