output: #fixed code
                               public void threadDumpIfNeed(String reasonMsg) {
  		if (!enable) {
  			return;
  		}
  
  		synchronized (this) {
  			if (System.currentTimeMillis() - lastThreadDumpTime < leastIntervalMills) {
  				return;
  			} else {
  				lastThreadDumpTime = System.currentTimeMillis();
  			}
  		}
  
  		logger.info("Thread dump by ThreadDumpper" + (reasonMsg != null ? (" for " + reasonMsg) : ""));
  
  		Map<Thread, StackTraceElement[]> threads = Thread.getAllStackTraces();
  		// 两条日志间的时间间隔，是VM被thread dump堵塞的时间.
  		logger.info("Finish the threads snapshot");
  
  		StringBuilder sb = new StringBuilder(8192 * 20).append("\n");
  
  		for (Entry<Thread, StackTraceElement[]> entry : threads.entrySet()) {
  			dumpThreadInfo(entry.getKey(), entry.getValue(), sb);
  		}
  		logger.info(sb.toString());
  
  	}
input: #vulnerable code 
                               public void threadDumpIfNeed(String reasonMsg) {
  		if (!enable) {
  			return;
  		}
  
  		synchronized (this) {
  			if (System.currentTimeMillis() - lastThreadDumpTime < leastIntervalMills) {
  				return;
  			} else {
  				lastThreadDumpTime = System.currentTimeMillis();
  			}
  		}
  
  		logger.info("Thread dump by ThreadDumpper" + reasonMsg != null ? (" for " + reasonMsg) : "");
  
  		// 参数均为false, 避免输出lockedMonitors和lockedSynchronizers导致的JVM缓慢
  		ThreadInfo[] threadInfos = threadMBean.dumpAllThreads(false, false);
  
  		StringBuilder b = new StringBuilder(8192);
  		b.append('[');
  		for (int i = 0; i < threadInfos.length; i++) {
  			b.append(dumpThreadInfo(threadInfos[i])).append(", ");
  		}
  
  		// 两条日志间的时间间隔，是VM被thread dump堵塞的时间.
  		logger.info(b.toString());
  	} 
                              #location 2 
                              #vulnerability type THREAD_SAFETY_VIOLATION