java get all threadlocal from thread

Posted 2021-03-18   智信智爱智强不息

 

 

public void mytest() {
    long start = System.currentTimeMillis();
    Thread thread = Thread.currentThread();

    Field threadLocalsField = null;
    try {
        threadLocalsField = Thread.class.getDeclaredField("threadLocals");

        threadLocalsField.setAccessible(true);

        Class threadLocalMapKlazz = Class.forName("java.lang.ThreadLocal$ThreadLocalMap");
        Field tableField = threadLocalMapKlazz.getDeclaredField("table");
        tableField.setAccessible(true);

        Object table = tableField.get(threadLocalsField.get(thread));

        int threadLocalCount = Array.getLength(table);
        StringBuilder sb = new StringBuilder();
        StringBuilder classSb = new StringBuilder();


        int leakCount = 0;

        for (int i = 0; i < threadLocalCount; i++) {
            Object entry = Array.get(table, i);
            if (entry != null) {
                Field valueField = entry.getClass().getDeclaredField("value");
                valueField.setAccessible(true);
                Object value = valueField.get(entry);
                if (value != null) {
                    classSb.append(value.getClass().getName()).append(", ");
             
                } else {
                    classSb.append("null, ");
                }
                leakCount++;
            }
        }

        sb.append("possible ThreadLocal leaks: ")
                .append(leakCount)
                .append(" of ")
                .append(threadLocalCount)
                .append(" = [")
                .append(classSb.substring(0, classSb.length() - 2))
                .append("] ");

        log.warn(sb.toString());
    } catch (Exception e) {
        e.printStackTrace();
    }
    long end = System.currentTimeMillis();
    long cost = end - start;
    log.info("获取ThreadLocal耗时:{}", cost);



结果： possible ThreadLocal leaks: 9 of 16 = [java.util.Collections$SynchronizedMap, null, 
java.lang.Boolean, java.lang.Boolean, null, java.lang.Integer, java.lang.Boolean, brave.propagation.TraceContext, null]