log exception without trace 异常信息

1.可用率报警后查看异常日志，发现打印的异常信息，没有堆栈信息

2.检查日志打印格式，是按照异常对象打印的，是正确的打印方式,代码如下

       try {
            ......
        } catch (Throwable t){
            LOGGER.error(ThreadLocalUtil.get() + "批量获取距离异常:", t);
            ......
        } finally {
            ThreadLocalUtil.clear();
        }

3.继续查询相关资料，发现是jvm做的优化

The compiler in the server VM now provides correct stack backtraces for all "cold" built-in exceptions. For performance purposes, when such an exception is thrown a few times, the method may be recompiled. After recompilation, the compiler may choose a faster tactic using preallocated exceptions that do not provide a stack trace. To disable completely the use of preallocated exceptions, use this new flag: -XX:-OmitStackTraceInFastThrow.

虚拟机打印堆栈超过一定次数以后，会关闭掉异常堆栈的打印，通过-XX:-OmitStackTraceInFastThrow 参数可禁用掉该优化

4.测试复现验证，代码如下

public class ExceptionTraceTest {
    public static void main(String[] args) {
        int i =0;
        String test = null;
        while (true){
            try {
                test.length();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

最开始的输出，异常信息中有堆栈信息

java.lang.NullPointerException
    at com.shuaisam.reboot.jvm.param.ExceptionTraceTest.main(ExceptionTraceTest.java:14)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.NullPointerException
    at com.shuaisam.reboot.jvm.param.ExceptionTraceTest.main(ExceptionTraceTest.java:14)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

输出一定数量以后，异常信息中只有异常message信息，没有了堆栈

java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException
java.lang.NullPointerException

5.加入jvm参数 -XX:-OmitStackTraceInFastThrow 重新运行代码

继续运行，一段时间后异常仍然全部打印出了堆栈，现象符合预期

6.解决办法

• 历史日志还在的话，查看历史日志异常堆栈
• 重新启动服务器，再观察日志
• 设置JVM参数，暂时禁止掉这个优化选项： -XX:-OmitStackTraceInFastThrow

7.参考资料

https://stackoverflow.com/questions/2295015/log4j-not-printing-the-stacktrace-for-exceptions